Issue 91 Winter 2021 Cosmos Magazine

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How will you science this National Science Week?

14–22 AUGUST 2021

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THE SCIENCE OF EVERYTHING

Issue 91 Winter 2021

TIME TRAVEL EARTH’S EPIC HISTORY AND THE FUTURE OF LIFE

New Ancestor? DNA detectives on the hunt Tetris and Telepathic Mice Mind meld made real High Revolution Gaia telescope’s galactic gaze

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AU $15.00 NZ $16.00

ESA / GAIA

Where is Gaia looking? This psychedelic swirl plots the viewing direction of the European Space Agency’s Gaia space telescope as it maps our galaxy. The craft sweeps its two telescopes around in four rotations per day, while also changing the orientation of its spin axis over 63 days. The colour of each line of dots represents the direction of the scan with respect to north (top of image) – indicated by the border, where each block of colour spans 18°. Densely overlapping lines denote areas that have been scanned many times in many directions, but the gaps will close as Gaia continues its work. Read more about Gaia on page 66.

COSMOS 91 JUNE – AUGUST 2021

FEATURES 26

JUST A BIT OF PERSEVERANCE The Mars 2020 rover’s landing and adventures have excited us all, and there’s more to come. TORY SHEPHERD talks with the Australians involved.

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SOLAR SYSTEM KNOWLEDGE OF FIRST AUSTRALIANS KIRSTEN BANKS and DUANE HAMACHER reveal First Nations Australians’ intricate understanding of the movements of the heavens.

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TIME TRAVEL AND TIPPING POINTS How to comprehend the vast concepts of geological time? LAUREN FUGE wanders through deep time – and discovers a key to our long-term survival along the way.

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WHERE’S MY FLYING CAR? The Jetsons predicted their invention in the famous cartoons. MARK PESCE investigates whether the “aero auto” is still pie in the sky.

MIND READERS What if mental telepathy was as simple as pulling on a cap and plugging into a colleague? PAUL BIEGLER reports on the laboratory experiments that are melding – and blowing – minds.

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FORCES OF NATURE The World Nature Photography Awards celebrate the call of the wild, and encourage us to protect what we have.

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GAIA’S ASTRONOMICAL LEGACY The European Space Agency’s awesome telescope continues to break new ground in astrometry. But RICHARD A. LOVETT discovers that they’ve only just begun to explore its potential.

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A SCIENTIST’S GUIDE TO DATING How to measure the age of the Earth? The lifespan of a whale? RACHEL WILLIAMSON explores the technologies measuring time – and the controversies that suggest that not all great minds think alike.

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THE CURIOUS CASE OF THE MISSING ANCESTOR Recent archaeological discoveries cast new light on the origins of our species. ELIZABETH FINKEL examines these bones of contention.

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REGULARS 8

DIGEST Dispatches from the world of science Oldest African burial 9 Focus: Life aquatic 12 Giant cloud rats 15 Guess the object 21

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NEXT BEST THING Physicist PAUL JACKSON explains why whispers about the Standard Model’s fidelity are gaining volume.

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ZEITGEIST 98

THE CHEMISTRY OF SOAP JACINTA BOWLER breaks down the humble household bar that is rinsing the COVID virus.

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MATHEMATICIAN AT THE MOVIES Ferris Bueller packed a lot into one day off. SIMON PAMPENA calculates whether the plot adds up.

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FUTURE FIREWORKS? AMANDA YEO wonders why Australia is slow to join the amazing drone-show party.

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MINDGAMES Fiendishly fun puzzles.

114 84 Ulysses, one of the last remaining great tuskers, Kenya, by Harry Skeggs. Gold prizewinner, black-andwhite category, World Nature Photography Awards.

PORTRAIT Galactic archaeologist IOANA CIUCA .

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SUBSCRIPTIONS Subscribe to Cosmos for eight issues and we’ll send two issues to a school or student of your choice. You’ll get free delivery to your door, access to 15 years of Cosmos archives – savings of $35. See page 94 for more details, or visit cosmosmagazine.com/ shop

Write a Pi-ku to celebrate ʋ

Science Is A Candle in the Dark. It illuminates And Unchains a Demon-Haunted World. Sachin

it sounds like a circular food but you cannot eat it. why can’t there be unique words for things? Tim

OUR COVER The striking depiction of deep time on the cover of Cosmos 91 was created by world-renowned graphic designer, illustrator and artist Noma Bar. Bar has illustrated more than 100 magazine covers – for publications as diverse as The Economist, Esquire and Wallpaper* – published hundreds of illustrations and released three books of his work: Guess Who –The Many Faces of Noma Bar (in 2008), Negative Space (2009) and Bittersweet (2017). Among his many industry awards is a prestigious Gold Clio in 2016 for his work on a campaign to highlight new frontiers in cancer treatments, for the New York Presbyterian Hospital.

THE SCIENCE OF EVERYTHING

Issue 91 Winter 2021

TIME TRAVEL EARTH’S EPIC HISTORY AND THE FUTURE OF LIFE

The competition closes on Two Pi Day, also known as Tau Day, for the mathematical constant, observed on 28 June (6/28 in month/ day format) and winners will be announced on Pi Approximation Day, 22 July (22/7 in day/ month format). Entries will be judged for style, originality and alignment with science and Pi. To enter, send us a Pi-ku at [email protected] 6 COSMOS MAGAZINE

New Ancestor? DNA detectives on the hunt Tetris and Telepathic Mice Mind meld made real High Revolution Gaia telescope’s galactic gaze

9 771832

522008

AU $ 5 00 NZ $ 6 00

DONATE By donating to The Royal Institution of Australia you are supporting our mission to find new ways for people to discover and understand science and how it shapes the world around us. To help us, visit: riaus.org.au/donate NEWSLETTER Each day we collate the most important and interesting science stories. Get regular updates of the top science news delivered straight to your inbox. Join at cosmosmagazine.com QUESTIONS? Have a question about your subscription or a change of address? Email us at [email protected] SOCIAL MEDIA Join more than half a million science fans on social media. facebook.com/CosmosMagazine instagram.com/CosmosMagazine twitter.com/CosmosMagazine

ABOUT THE ROYAL INSTITUTION OF AUSTRALIA The Royal Institution of Australia is an independent charity dedicated to connecting people with the world of science. Through Cosmos magazine, our free daily science news site cosmosmagazine.com, our e-publication Cosmos Weekly and free educational resources, we aim to be an inspirational resource centre for the wonders and achievements of Australian and the world’s scientific discoveries. We want to spark in all people a desire to be science literate and to make informed decisions about their lives based on rigorously sought and tested evidence.

TOP: POLYGRAPHUS / GETTY IMAGES

AT THE ROYAL INSTITUTION OF AUSTRALIA, we’ve been celebrating that most special of numbers with the Cosmos Pi-ku 2021 competition. A haiku in English is generally accepted to be a poem of three lines and 17 syllables arranged in a 5–7–5 pattern. A Pi-ku (for our purposes) is a poem of six lines and 23 syllables arranged in a 3–1–4–1–5–9 pattern (Pi to five decimal places: 3.14159). Started on Pi Day – March 14 (3.14 to people in the US), we’ve had some delightful entries, which you can read at cosmosmagazine.com. A couple to whet your appetite:

THE GIFT OF SCIENCE Gift subscriptions start from just $49 including delivery to your door, plus access to 15 years of Cosmos archives.

ISSUE 91

Editor Gail MacCallum Digital Editor Ian Connellan Art Director Kate Timms Graphic Designer Greg Barton Science Journalists Deborah Devis, Lauren Fuge, Ellen Phiddian Editorial Intern Amalyah Hart Social Media Manager Kelly Wong Editor-at-Large Elizabeth Finkel CONTRIBUTORS Kirsten Banks, Paul Biegler, Jacinta Bowler, Duane Hamacher, Paul Jackson, Richard A. Lovett, Simon Pampena, Mark Pesce, Tory Shepherd, Graem Sims, Rachel Williamson, Amanda Yeo. Mind Games Tess Brady / Snodger Puzzles SUBSCRIPTION Subscriptions Tammi Parsons [email protected] cosmosmagazine.com/shop Delivery issues: +61 8 7120 8600 THE ROYAL INSTITUTION OF AUSTRALIA Executive Director Will Berryman Lead Scientist Prof Alan Duffy Chief Operating Officer Chuck Smeeton Corporate Services Manager Sarah Brennen Executive Producer Katherine Roberts Education Manager Jennifer Chalmers Video Producer/Graphic Designer Marc Blazewicz OFFICE CONTACT cosmosmagazine.com Editorial enquiries [email protected] +61 8 7120 8600 PO Box 3652, Rundle Mall SA 5000 Australia Published by The Royal Institution of Australia Inc. ABN 98638459658

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From the Editors A STORY ABOUT geological time, another covering the intriguing search for an ancient human ancestor, and a third investigating the ESA’s Gaia space telescope wouldn’t appear to have much in common. In fact, they’re at the centre of this issue’s focus on deep time. Staff writer Lauren Fuge is our rock conductor, orchestrating a journey from the Ediacaran Period to the present, en route discovering as much about humanity as geology. Ella Finkel joins genetic detectives on the hunt to find the link between Denisovans and modern humans, and Rick Lovett gives us a look into the depths of deep space through Gaia’s clear, steady gaze. Staying in space, our series on Indigenous astronomy continues as Kirsten Banks and Duane Hamacher look at First Nations Peoples’ view of our near-neighbour planets, while Tory Shepherd sends up another cheer for the Mars rover Perseverance and its tiny but mighty experimental rotorcraft, Ingenuity. Closer to Earth, Mark Pesce says we’re a few steps closer to electric flying ‘cars’ – but don’t sell the family sedan anytime soon – and Rachel Williamson takes a look at the complex science of working out how old things are. In the Zeitgeist section, Simon Pampena offers a mathematician’s take on a classic ’80s film – could Ferris Bueller really have done all that stuff in that time and distance? – and Amanda Yeo considers the firework-replacement potential of massed drone displays. We wash the whole thing down with Jacinta Bowler’s look at the science of soap. And in this age of certain uncertainty, we’ve created more chances to escape into excitement and discovery with our new weekly e-publication, Cosmos Weekly. All the news, with more of the science. We’d love it if you took a look at www.thecosmosweekly.com and let us know what you think. Meanwhile, enjoy the issue, and the chance to time travel from your comfy reading spot into the different worlds that science brings.

GAIL MacCALLUM Editor IAN CONNELLAN Digital editor cosmosmagazine.com 7

At the base of a threemetre trench in the Panga ya Saidi cave, the child’s bones were carefully excavated – including a skull, spine and femur. These were fragile and severely degraded, so 3D models were created to preserve the child’s original position. A photo of the partial skeleton, skull and mandible can be seen opposite.

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DIGEST Science news from the around the globe

ARCHAEOLOGY

Oldest human burial in Africa unearthed

OPPOSITE PAGE, CLOCKWISE FROM BOTTOM LEFT: MOHAMMAD JAVAD SHOAEE. JORGE GONZALEZ / ELENA SANTOS X5. THIS PAGE: MARÍA MARTINÓN-TORRES

Discovery sheds light on the evolution of modern human behaviour.

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bout 78,000 years ago, at the mouth of a cave complex in modern-day Kenya, someone placed the body of a three-year-old child on its side in a purpose-dug grave and covered it with earth from the cave floor. This intentional act – described in a paper in Nature – is the oldest human burial ever uncovered in Africa. “It’s a first,” says Alison Crowther, co-author and archaeologist from the University of Queensland. “Africa is the cradle of our species, Homo sapiens, but we don’t really have much evidence of early burial practices from anywhere on the continent, and practically none from eastern Africa.” This discovery, she says, “gives us this extraordinary, unprecedented glimpse into how our species evolved, both culturally and anatomically”. The child – nicknamed Mtoto, meaning ‘child’ in Swahili – was found in Panga ya Saidi cave, on the Kenyan coast about 400 kilometres from today’s capital, Nairobi. The body was placed in a flexed position, lying on its side with knees drawn towards the chest, suggesting it may have been tightly shrouded. The pattern of collapse of the head and neck also suggest that a perishable material was placed underneath the head for support.

“It clearly demonstrates intentional burial and treatment of the dead at 78,000 years ago,” says co-author Patrick Faulkner from the University of Sydney. “These are complex behaviours linked to complex emotions. We do see complex behaviour through things like personal ornamentation and symbolism, but this burial adds quite a lot to our understanding of symbolic and conceptual complexity in human populations.” Intentional burials of modern humans and Neanderthals dating back 120,000 years have been discovered in Eurasia. In Australia, the famous Mungo Man and Mungo Lady – a

burial and cremation respectively – were uncovered in western New South Wales in the late 1960s and early ’70s. Dated to around 40,000 years ago, their discovery rewrote our understanding of Australian history. But only a handful of early human burials have been found in Africa, despite evidence that it is the birthplace of modern humans. This could be explained by differences in mortuary practices, or even a lack of research fieldwork in large portions of the continent. Germany’s Max Planck Institute, in partnership with the National Museums of Kenya (Nairobi) and archaeologists from around the world were excavating the archaeologically rich cave to study trade in the Indian Ocean from several thousand years ago. As they dug deeper they found evidence of early symbolic behaviour, such as ochre use and beads over 60,000 years old. Then in 2013 the child was unearthed, and in 2017 a plaster cast of the bones was taken to the National Research Center on Human Evolution (CENIEH) in Burgos, Spain, for study. Crowther thinks that as fieldwork in Africa continues, even older burial sites will be found. “We know that humans have the capacity for symbolic thought that goes much earlier,” she says. cosmosmagazine.com 9

Glaciers are shrinking faster Scientists study more than 200,000 glaciers to estimate global ice loss – with distressing results.

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study of nearly every glacier on Earth has confirmed they are losing more ice every year. The international research team, led by Roman Hugonnet from the Université de Toulouse in France, found that on average these icy rivers have lost 267 gigatonnes (Gt) of mass per year since 2000. A Gt is equal to the mass of a one-kilometre-sided cube of water, or about 400,000 Olympic swimming pools. It gets worse: the study, published in Nature, also found that the rate of ice loss is accelerating by an average of 48 Gt per year each decade. 10 COSMOS MAGAZINE

The paper highlights that this ice loss accounts for a significant amount (21%) of global sea level rise. As the research team warns, “200 million people live on land that is predicted to fall below the high-tide lines of rising sea levels by the end of the century.” The researchers analysed archives of high-resolution satellite and aerial images of 217,175 glaciers – 97.4% of the world’s total. As Lauren Vargo, from the Antarctic Research Centre at the Victoria University of Wellington in New Zealand, explains, this isn’t the first study to calculate global glacier mass from satellite

Klinaklini Glacier is the largest glacier in western Canada (nearly 500km²).

observations, but the results are important largely because the authors were able to calculate global glacier mass change much more precisely than in previous studies. The latest IPCC report, for example, estimated the global mass loss of glaciers at 278 Gt per year, but with an enormous uncertainty of ± 226 Gt. In contrast, this new study finds a comparable estimate (267 Gt per year) but reduces the uncertainty to just ± 17 Gt per year. “Being able to more precisely measure how glaciers are currently changing is important for creating policy and management around impacts including changes in hydrology, rising sea level and increasing natural hazards,” says Vargo. “These more precise measurements are also important because they enable us to do a better job of modelling how glaciers will continue to change in the future and then better predict the impacts of those future changes.”

BRIAN MENOUNOS

CLIMATE

DIGEST

ANTHROPOLOGY EARTH

SEAWEED EASES CATTLE BURPS A small amount of seaweed could reduce agricultural methane emissions.

(COW) BREANNA ROQUE / UC DAVIS

Livestock account for around 15% of annual greenhouse gas emissions worldwide. A large part of this is methane, burped from cattle. But new research, published in PLOS ONE, has found that a particular genus of seaweed could play a big role in reducing methane made by beef cattle. Lab studies had shown that seaweed in the Asparagopsis genus might be an effective methane antagonist, and an Australian study had identified one species, Asparagopsis taxiformis, as the most promising candidate. The new study fed small amounts of the seaweed to cattle to see if these results were repeatable in the field. Researchers found that steers on the seaweed diet consistently burped less methane than their no-seaweed counterparts. Depending on other variations to their diet – such as foraging and total amount of food eaten – this reduction was as much as 82%. “There is more work to be done, but we are very encouraged by these results,” says Breanna Roque, lead author on the study.

What can machine learning tell us about the rock art in Arnhem Land? Computers compare minute style details.

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outh Australian researchers, led by Daryl Wesley of Flinders University, working with the Mimal and Marrku traditional owners of the Wilton River area in the Northern Territory, took a look at rock art in Arnhem Land to examine how it transformed stylistically over time. The team used machine learning to analyse images of different styles and subjects, to see how similar they were at a minute level, and determine the chronology of art evolution. “One amazing outcome is that the machine learning approach ordered the styles in the same chronology that archaeologists have ordered them in by inspecting which appear on top of which,” says Jarrad Kowlesser, one of the researchers at Flinders University. “This shows that similarity and time are closely

linked in the Arnhem Land rock art and that human figures drawn closer in time were more similar to one another than those drawn a long time apart. “For example, the machine learning algorithm has plotted Northern Running Figures and Dynamic Figures very close to one another on the graph it produces. “This shows that these styles which we know are closer to each other in age are also closer to each other in appearance, which might be a very hard thing to notice without an approach like this.” The team first taught the computer how to recognise different images by using an existing dataset of 14 million photos of animals and objects. This model was then applied to the rock art images. The results are published in Australian Archaeology. The code has been made available via GitHub. cosmosmagazine.com 11

03 MARINE LIFE

Octopuses change colour when they sleep. Octopus insularis turns pale blue in non-REM ‘quiet’ sleep, and pulses in colour during REM ‘active’ sleep.

FOCUS: LIFE AQUATIC 01 Fish of the Cirrhilabrus genus (below) can thank the last ice age for their diversity. Sea level flux isolated some populations and allowed others to mix, so males developed colour patterns to differentiate themselves.

02 Fish have been leaving equatorial waters over the past six decades. As climate change has made the equator warmer, species in those areas have moved south or north.

04 shark – kitefin, lucifer and southern lantern – glow in the dark. They have organs called photophores on their underbellies, which glow a pale blue and may help them camouflage against the bright surface.

05 Zebrafish larvae have good hearing. They’re able to detect sounds in the 600–4000 Hz range, whether it’s the sound of another fish swimming by… or rap music.

Ocean eddies – swirling masses of water, tens to hundreds of kilometres in width, that drive global weather and ocean currents – have been increasing in energy and activity over the past 30 years, satellite data shows.

www.cosmosmagazine.com/ 01 science/biology/dazzle-to-survive 02 nature/marine-life/marine-species-flee-the-equator 03 nature/marine-life/octopuses-change-colour-based-on-sleep-cycle 04 nature/marine-life/glow-in-the-dark-sharks 05 nature/marine-life/fish-dj-drops-marine-beats 06 earth/oceans/energetic-ocean-eddies-on-the-rise

YI-KAI TEA

Three species of deepwater

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DIGEST

TECHNOLOGY

WEARABLE TECH-STYLE Throw on a washable fabric that can act as a display screen.

SPACE

Astronomers find “Goldilocks” black hole is just right Early black holes may seed their more massive cousins.

TOP: CARL KNOX, OZGRAV. RIGHT: HUISHENG PENG’S GROUP

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ast year, scientists used gravitational waves to detect an elusive intermediatemass black hole for the first time. Now, Australian astronomers have spotted another – this time using gamma-ray bursts. Black holes are formed when massive stars reach the end of their lives and collapse under their own gravity. But they aren’t all the same – stellar mass black holes are small, just a few times the mass of our Sun, while supermassive black holes at the hearts of galaxies are enormous, with masses millions or even billions of times greater than our Sun. Intermediate mass black holes are the missing link between these two populations, thought to span between 100 and 100,000 solar masses. The black hole discovered in 2020 was 142 solar masses.

This newly discovered monster comes in at approximately 55,000 solar masses. The study, published in Nature Astronomy, describes detecting the black hole via a gravitationally lensed gamma-ray burst – a flash of high-energy light emitted when two distant stars collided. “This newly discovered black hole could be an ancient relic – a primordial black hole – created in the early universe before the first stars and galaxies formed,” explains study co-author, Eric Thrane from Monash University. “These early black holes may be the seeds of the supermassive black holes that live in the hearts of galaxies today.” The study estimates that there are around 46,000 black holes of this mass in our neighbourhood of the Milky Way alone.

Researchers in China have created a durable, wearable textile that features a large-area electronic display. Created from cotton integrated with conductive and luminescent fibres, the fabric can withstand 100 cycles of washing, and is breathable and flexible enough to be comfortably worn. The research team made a test version of the textile six metres long and 25 cm wide, complete with a built-in solar panel, a touch-sensitive keypad and a Bluetooth connection. The fabric’s warp is a luminescent fibre created out of a zinc sulphide phosphor combined with cotton yarn. Its weft was made from polyurethane gel and cotton yarn, and is used as the conductor between the luminescent fibres. In the test fabric, there are glowing points 800 micrometres apart where the warp and weft cross that can be used like a screen to display simple images. “We expect that woven-fibre materials will shape the next generation of electronics,” write the researchers in their paper, published in Nature.

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MEDICINE BIOLOGY

How teeth sense cold temperatures

CATS LOVE IT BUT MOZZIES DON’T Scientists reveal why catnip is a potent insect repellent.

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cientists have located a protein that lets teeth sense cold temperatures in a new paper published in Science Advances. The protein, TRPC5, is an ion channel: a molecular tube that can open and shut, letting ions through that trigger electrical impulses. It appears in several parts of the body – in fact, when researchers from the Howard Hughes Medical Institute (HHMI) in the US began to examine it 15 years ago, they looked at its effect in skin. “We hit a dead end,” says team member Katharina Zimmermann, now an electrophysiologist in Germany. But she continued to mull the problem over with David Clapham, a neurobiologist at HHMI, and fellow researchers. “One day, David said, ‘Well, what other tissues in the body sense the cold?’,” says

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Zimmerman. They began to investigate teeth. This new research shows that TRPC5 is present in teeth, and that it connects to the nerves. It appears in cells called odontoblasts, which are normally well protected but can become exposed from tooth decay. Researchers investigated mice without TRPC5 in their teeth, alongside a control group of mice with teeth treated with a chemical that blocked the protein. In the control mice, an icy solution touching the teeth prompted a nervous response. Another protein, TRPA1, seemed to have an effect as well. In the proteinless mice, there was no response. This research explains why clove oil may alleviate tooth pain, as it contains a chemical that blocks the TRPC5 protein, preventing it from triggering nerves.

Cross section of a mouse’s molar, showing the coronal pulp (red) in the tooth’s centre and TRPC5 ion channels (green) within odontoblast cells. The cells’ long-haired extensions fill the thin canals in dentin that extend towards the enamel (at base).

Scientists have used cultured cells expressing the TRPA1 (transient receptor potential ankyrin 1) genes – a molecular mechanism for “pain” and response to irritants discovered in flies, mozzies and humans – to test if they are activated by catnip and its active ingredient nepetalactone, according to a study published in the journal Current Biology. The protein is known as the “wasabi receptor” (the eye-watering sensation caused by eating the Japanese horseradish), but although humans and other animals have it, catnip doesn’t affect us in the same way. The team also tested catnip on mutant mosquitoes and flies without the TRPA1 receptor and found they lost their aversion to the herb. FROM FAR LEFT: L BERNAL ET AL / SCIENCE ADVANCES 2021 . GALLIO LAB / NORTHWESTERN

New research identifies a protein in teeth that senses a biting chill.

DIGEST

PALAEONTOLOGY

Fossils of extinct “giant cloud rats” found in the Philippines Surprise discovery suggests the region was more diversely populated than previously thought.

VELIZAR SIMEONOVSKI, FIELD MUSEUM

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iecing together fossil remains of jaws and teeth in the Philippines, archaeologists have unearthed evidence of three new giant cloud rat species that lived until just a few thousand years ago. The new arboreal, herbivorous species, Batomys cagayanensis, Carpomys dakal and Crateromys ballik, add to the richness of the region’s native fauna history. Two of the species, which come from the Phloeomyini tribe, would have been around for about 60,000 years, the team reports in the Journal of Mammalogy, suggesting that the mammals were resilient before they suddenly disappeared. “These giant rodents were able to survive the profound climatic changes from the ice age to current humid tropics that have impacted the Earth over tens of millennia,” says co-author

Philip Piper from the Australian National University. “The question is, what might have caused their final extinction?” The remains were discovered in and around Callao Cave on Luzon Island, where excavations seeking insights into early hominins in the Philippines turned up Homo luzonensis fossils in 2010. The enduring cloud rat species seem to have disappeared around the same time that pottery and Neolithic stone tools appeared and when dogs, domestic pigs

“These rodents were able to survive climatic changes from the ice age to current humid tropics… what might have caused their final extinction?”

Illustration showing how the three new species of fossil cloud rats – Batomys cagayanensis, Carpomys dakal and Crateromys ballik – might have looked.

and possibly monkeys were introduced, says co-author Armand Mijares from the University of the Philippines. “While we can’t say for certain based on our current information, this implies that humans likely played some role in their extinction.” After discovering the fragments, the team added them to existing fossils excavated several decades ago. Altogether, they had only 50 or so fragments to work with. “Normally, when we’re looking at fossil assemblages, we’re dealing with thousands and thousands of fragments,” says lead author Janine Ochoa, also from the University of the Philippines. “It’s crazy that in these 50 fragments we found three new species that haven’t been recorded before.” cosmosmagazine.com 15

PHYSICS

W boson spotted in Antarctica

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n 6 December 2016, a high-energy particle hurtled from outer space and through an Antarctic ice sheet, where it slammed into an electron at nearly the speed of light. The enormously energetic collision created a completely different particle, which rapidly decayed into a cascade of others. This event might have gone unnoticed, if a massive matrix of neutrino-detectors hadn’t been sunk into the ice, ready to capture such astrophysical phenomena. In a paper published in Nature, high-energy astrophysicists at the IceCube Observatory in Antarctica confirm that this 2016 collision provides observational evidence for a theory put forth in 1960, solidifying our

understanding of the Standard Model of particle physics. Called a Glashow resonance event, the phenomenon was first described by physicist Sheldon Glashow. He predicted that if an antineutrino with just the right amount of energy collided with an electron, it would create a thenundiscovered particle through a process called resonance. This mysterious particle – the W boson – is an elementary particle with an electric charge. Along with the Z boson, it mediates the weak force, which is one of the four fundamental forces that govern how matter behaves. When it was discovered 23 years later by CERN’s Large Hadron Collider via a different particle interaction, physicists

It was one of the highest-energy events ever detected by the IceCube observatory; only two other events have had an energy greater than 5 PeV. 16 COSMOS MAGAZINE

On a plateau near the South Pole, IceCube searches for elusive, nearly massless particles called neutrinos. But it isn’t your average telescope – the real work is done beneath the surface. Over 80 strings of detectors are sunk into the ice, creating a cubic-kilometre array of “eyes on the sky”.

realised that the W boson was much heavier than expected. This amended Glashow’s prediction: for a W-boson to be created via an antineutrino-electron interaction, the antineutrino would need to have an astonishing energy of 6.3 petaelectronvolts (PeV). This is 1000 times more energy than the Large Hadron Collider can produce – and that’s currently the most powerful particle accelerator in the world. Since physicists couldn’t simulate a Glashow collision in the lab, they instead had to wait for a cosmic coincidence. Supermassive black holes and other extremely energetic astrophysical processes can act like natural particle accelerators, but not only do they have to accelerate an antineutrino to the right energy, and not only must it be sent on the right trajectory to collide with the Earth, it needs to hit in the square kilometre of Antarctic ice where the IceCube Observatory’s detectors are watching. Needless to say, scientists have been waiting a while. The IceCube Observatory was operational in 2011; this 2016 hit is its first W-boson. The results of the collision analysis show that it was one of the highest-energy events ever detected by the IceCube observatory; only two other events have had an energy greater than 5 PeV. Glashow, now an emeritus professor at Boston University, is looking to the future. “To be absolutely sure, we should see another such event at the very same energy as the one that was seen. So far there’s one, and someday there will be more.”

ICECUBE / NSF

IceCube observatory spots elementary particle needle in a galactic haystack.

DIGEST

PALAEOBOTANY

Pompeii of prehistoric plants Excavating the ancestors of seed-bearing flora.

BIOLOGY

DINGOES AREN’T “WILD DOGS”

ABOVE: CHONTELLE BURNS, NEUVEAU RISE PHOTOGRAPHY, NEWCASTLE. RIGHT: UNIVERSITY OF BIRMINGHAM

DNA analysis finds little interbreeding with domestic canines. A new study has found that most Australian dingoes have pure dingo ancestry, certifying their importance as native apex predators rather than pests. The research, published in the journal Australian Mammalogy, found virtually no feral dogs across the continent and very little evidence of interbreeding between dingoes (Canis lupus dingo) and domestic dogs (Canis familiaris). “The results challenge the widespread use of the term ‘wild dog’,” says lead author Kylie Cairns from the University of New South Wales. “It is important that governments, wildlife managers and agriculture industry groups use the name dingo to describe these wild canines because this is what they are. “The finding that there are very few feral dogs in the wild suggests there is something ecologically and biologically different between dogs and dingoes and that really an animal must be mostly dingo to survive in the wild.”

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ew analysis of Chinese tree fossils has revealed that they are the ancestors of the seed-bearing plants that dominate the Earth today. Noeggerathiales was a peatforming order of plants that lived 325 to 251 million years ago (mya), before the rise of the dinosaurs and while the Earth’s land was arranged into the supercontinent Pangea. Specimens were first discovered in the 1930s, but a dearth of well-preserved fossils prevented scientists from accurately placing them in the plant kingdom. “Thanks to this slice of life preserved in volcanic ash, we were able to reconstruct a new species of Noeggerathiales that finally settles the group’s affinity and evolutionary importance,” says co-author Jason Hilton, from the University of Birmingham, UK. Hilton was part of a team led by palaeontologists at the

University of Birmingham and the Nanjing Institute of Geology in China. Their paper, in the journal PNAS, describes how they studied a complete Noeggerathiales fossil preserved in a bed of volcanic ash 66 cm thick, formed 298 mya. This unique preservation provides a snapshot of a moment in time, just as the excavation of Pompeii provided a glimpse of ancient Roman life. The team found that Noeggerathiales are more closely related to seed plants than to other fern groups, even though they appear fern-like, with complex cone-like structures evolved from modified leaves. They also deduced that the ancestral lineage of seed plants diversified during the Devonian, Carboniferous and Permian periods (approximately 419–252 mya), and went extinct around 251 mya, during the Permian-Triassic extinction event.

cosmosmagazine.com 17

MEDICINE PALAEONTOLOGY

HOW MANY T. REX EVER LIVED? BILLIONS Counting the iconic carnivores that roamed the Earth.

18 COSMOS MAGAZINE

How do COVID variants emerge? Evidence points to people with weak immune systems.

S

How many T. rexes existed on planet Earth? Billions, give or take a lot of uncertainty.

ince its first appearance in Wuhan, China, SARSCoV-2 has been acquiring random mutations. In recent months several new variants have been observed. Some of those cause significant changes in how the virus behaves, including how contagious or deadly it is. Mutations happen all the time and are entirely random. “It’s just what viruses do,” says Gilda Tachedjian, a virologist at the Burnet Institute and president of the Australian Virology Society. If we sequenced all the virus particles – virions – from someone infected with SARSCoV-2, we’d find that each particle is slightly different. That’s because when viruses make copies of themselves, they make mistakes. Most of these go completely unnoticed. Others confer advantages to the virus and gradually become predominant. The rapid evolution of the virus

has been documented in a number of patients in the UK and US. Researchers from Cambridge University following a 70-year-old man who was immunocompromised noticed that the virus evolved rapidly after the man received plasma therapy. The virus produced “escape mutations” that helped it to evade detection by the antibodies in the plasma. A 45-year-old Boston man undergoing immunosuppressive therapy was hospitalised with a COVID-19 infection that recurred for 154 days until he died. Rapid evolution was also reported in an immunocompromised patient who remained asymptomatic over several months. “It comes back to that ability of the virus to replicate, to introduce mutations,” says Tachedjian, “and then to evolve so that it’s able to escape the weak immune response that immunocompromised individual might have.”

LEFT: ROGER HARRIS / SPL / GETTY IMAGES. ABOVE: ANDRIY ONUFRIYENKO / GETTY IMAGES

Palaeontologists have crunched the numbers to estimate just how many Tyrannosaurus rex lived and died – and the answer could be in the billions. This new study, published in Science, estimates that about 20,000 adult T. rex lived at any one time and that the species persisted for about 127,000 generations – meaning 2.5 billion walked the Earth in total. Lead author of the study, Charles Marshall, says the project started off as a “lark”. “When I hold a fossil in my hand, I can’t help wondering at the improbability that this very beast was alive millions of years ago, and here I am holding part of its skeleton,” says Marshall, a professor at UC Berkeley, US. Large uncertainties about population at any given time mean that the real number could be as low as 140 million or as high as 42 billion. Though these calculations will undoubtedly be challenged by other palaeontologists, the framework for estimating extinct populations could be useful to apply to other species.

DIGEST

EARTH

Greenland’s lost and found forest Misplaced core sample shows plant bounty, but it’s not good news.

JOSHUA BROWN / UVM

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n a bizarre story of lost and found, scientists have learnt Greenland might have been forest green only a million years ago. An international team of scientists, led by Paul Bierman of the University of Vermont, analysed a 1.6km deep, 54-yearold sample of plant-fossilfilled dirt taken from below Greenland’s ice. They found that the abundance of plant fossils may have meant Greenland was ice free within the last million years –

perhaps even only a few hundred thousand years ago. The fivemetre dirt sample was originally taken in 1966 but got lost in a freezer. When it was rediscovered in 2019, Andrew Christ, from the University of Vermont, examined the sample under a microscope and found it was packed full of twigs and leaves instead of just sand and rock. “Ice sheets typically pulverise and destroy everything in their path,” says Christ, “but what we discovered was delicate plant

Greenland’s melting ice landscape may actually be restoring its forest cover.

structures – perfectly preserved.” Their paper, published in PNAS, shows that Greenland was icefree at some time during the Pleistocene – 2.6 million years of repeated glaciation with short peaks of warmth that ended around 120,000 years ago. The Pleistocene was considered a colder time than now, so the ice in Greenland may be very sensitive to a temperature variation, suggesting we could experience another similar melt as our current climate warms, too.

SPACE

Spotting spot fires from space

S

torm-chasing drones, smart water bombers and a constellation of bushfirespotting satellites could be the key to reducing Australia’s devastating bushfire toll. Imagine if lightning strikes a tree in a remote valley. A satellite detects it via infrared sensors and notifies a drone. The cameraequipped drone zips to the site, and the blaze is confirmed. Then a C-130 plane, flying high and safe overhead, drops a watercarrying glider with an automated guidance system over the fire, putting it out before it can become a devastating bushfire. That’s just part of the ambitious fire-fighting plan being developed by the Australian National University National 20 COSMOS MAGAZINE

Bushfire Initiative. Working with Optus, they plan to launch the satellites in 2022. Initiative director Marta Yebra says they’re working on a range of technologies that will also monitor fuel loads, moisture levels and weather. But there’s more. “For example, on-ground sensors for early fire detection – but they have very limited range in terms of the areas…so they can only be mounted in specific places, like places at high risk, or on highways, or places of high ecological value that you want to protect,” she says. “Then you have another layer that would be cameras mounted in towers that have a bigger range of view, and then we have drones – as we go up we have a larger

NOAA satellite images of the 2019 bushfires in Australia.

landscape overview, and then ultimately low Earth orbit and geostationary satellites.” Drones can be equipped with technology that will identify the driest areas, as well as areas with the biggest fuel loads. “If you combine that with the prediction of lightning, for example, the drones can chase the lightning storms,” Yebra says. “So you can then deploy them based on fire risk.” Queensland start-up Fireball International is using similar technology in California, and has started testing in Australia. It recently signed a deal with Space Machines Company to put its satellite into orbit in 2022 using a Gilmour Space Technologies rocket.

NOAA / NESDIS / WIKIMEDIA COMMONS

Eyes in the sky may help put out bushfires within minutes.

DIGEST

CHEMISTRY

CHEMICAL COLOURING IN Scientists design a polymer that changes colour depending on length

SUIYING YE / ETH ZURICH

Fluorescent molecules are useful for lighting, solar cell research, medical imaging, and biological lab tests like PCR tests, but it is difficult to achieve precise colours in fluorescent dyes. Now, a new paper published in Science Advances has described a polymer that can be adjusted to fluoresce, or “glow”, in finely tuned colours – without major changes to its chemistry. Researchers based at ETH Zurich in Switzerland and the Royal Melbourne Institute of Technology have designed polymers made from molecules that are similar to the structure of polystyrene, called organic styrenic molecules. What’s special about this is that these differently luminescent polymers are all composed of the exact same components. The only difference is the chain length. The polymer has applications in lab diagnostic tests, solar cell development and possible security features on items such as banknotes and passports.

GOLD-PLATED GUESSING Has anyone noticed that we’re excitable about scientific discovery? The pleasure lies in bright minds wondering about, and then creating, experiments, equations or apparatus to help solve their question. These men – one of them the patentee of a device that informed this one – are showing off something (at the time) novel. It’s, aha, a golden time for discovery, a fact underlined by the crisply creased dustcoats in this press call. The patentee, rightly revered, died late last year; he qualified for a René Descartes-ism: “It is not enough to have a good mind. The main thing is to use it well.” We know you can Google, but where’s the fun in that? Tell us what you think it is. Bonus points for the names of the men shown. The correct answer – and/or the most creative – will be published in the next issue. Send your hunches to [email protected]

Last issue’s object proved tricky to some, but not all. “It looks like a level measuring device, to determine how flat something is (although it doesn’t really look

precise enough to be honest),” wrote Evie. Ronakraj Gosalia agreed, “An old-fashioned spirit level… Am I close?” “Like an hourglass, but it uses water, not sand,” wrote previous GTO winner Paul van Leeuwen. But the winning guess wasn’t even a guess: “It’s for measuring… the standard electrical volt,” wrote Lana Little, our first correct answer. “My husband Tony took one look…and said, ‘There’s

nothing else looks like that – it’s a Standard Cell, a Weston Cadmium Cell – unmounted’.” Lana added: “Invaluable in the days before we could pop down to the local hardware and snare a pre-calibrated multimeter.” Charles Tivendale also recognised it, but offered this additional delight: “A refill for the old red and black dual typewriter ribbons. The ink is concentrated and stored under oil to reduce evaporation.” cosmosmagazine.com 21

DIGEST

PHYSICS

GOOD (SPIDER) VIBRATIONS

GEOLOGY

Pilbara rocks speak of Earth’s first continents A new study of rocks in Western Australia’s Pilbara region rewrites the history of early continent formation on our planet.

A

new study of the famous iron-red rocks in Western Australia’s arid Pilbara region has revealed that the formation of Earth’s first continents occurred in a different way than originally thought. The research, published in the journal Nature, sought to understand how the granite that made up the Earth’s earliest continents at the end of the Archaean eon (some 2.5 billion years ago) was formed. Critically, the researchers wanted to find where the water required for the granite’s formation came from. To understand what Earth’s early history may have been like, the researchers tested the variation of oxygen isotope composition of zircon and compared this with the geochemistry of the rocks from the Pilbara. 22 COSMOS MAGAZINE

They found that the water in the type of granite present could not have come from the sky. The study proposes that rather than coming from above, the water came from hydrated near-surface basalt rocks that were circulated into the Earth’s mantle through the process of overturn of the crust. If this is correct, it means that rock formation processes in Earth’s early history were incredibly different from today. Under these strange conditions, this mantle water may have been instrumental in forming the continents during Earth’s early years. The study was a collaboration between Curtin University, the University of Western Australia, Geoscience Australia, and the Geological Survey of Western Australia.

Cross-sectional images (shown in different colours) of a spider web were combined into this image and translated into music.

The fascinating properties of spider webs could now be explored in an entirely new dimension: music. The experience could offer not only new musical inspiration but also insights into how spiders create their masterpieces, according to scientists at the online spring meeting of the American Chemical Society. “The spider lives in an environment of vibrating strings,” says lead investigator Markus Buehler, from MIT, US. “They don’t see very well, so they sense their world through vibrations, which have different frequencies.” His team notes that mapping out the structure and properties of the fine, microscopic 3D webs has proven challenging until now. To throw a new perspective on it, Buehler and colleagues scanned a natural spider web in 2D cross-sections which they translated into its 3D structure using computer algorithms. “This network provides a model that contains all of the structural and topological features of the porous regions of a 3D web with high fidelity,” they write.

FROM TOP: TED MEAD / GETTY IMAGES. ISABELLE SU AND MARKUS BUEHLER

Scientists create music from arachnid webs.

It’s here! Every day brings a new discovery, a fresh insight. Keep up with science and get the facts behind the news with Cosmos Weekly, online each Friday. Subscribe today and get 4 weeks FREE!

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Is the Standard Model broken?

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e find ourselves on the cusp of what could be a turning point in fundamental physics. Within weeks of each other, the Muon g-2 experiment at Fermilab in the US and the LHCb experiment at CERN, in Switzerland, reported eagerly anticipated results, which have particle physicists wobbling with excitement. Both experiments are testing the Standard Model of Particle Physics in different but complementary ways. The results indicate that it’s time to strap ourselves in for a bumpy ride along what might become an increasingly broken Standard Model highway. For starters, what is the “Standard Model”? Confusingly, it’s neither standard nor a model, but in fact an amazing theory: a set of mathematical laws that describe 24 COSMOS MAGAZINE

how the universe operates, specifically the fundamental interactions between elementary particles and the forces that bind them. The theory, beautiful as it is, has some missing pieces – it doesn’t explain itself and is somewhat ad-hoc. It’s like the frustrating genius in school, who always gets the right answer but never explains how or why they worked it out. The Standard Model has withstood a barrage of intense scrutiny for decades, and whatever we do – collide particles, stare into space, poke around in atoms – it seems to work. Or does it? The muon causing all this fuss is really just a fat, skittish electron: 200 times more massive with a lifetime of about one millionth of a second. Like all fundamental particles, muons have “spin”: a quantum mechanical property, similar to how we think of spin in a classical sense. Like electrons, muons also have electric charge; when they move they produce a current and subsequently a magnetic

field. When placed in an external magnetic field, muons “precess” (the axis starts to tilt like a spinning top slowing down) at a rate that we can calculate and predict precisely. This value is known as the gyromagnetic ratio “g” and was initially predicted to equal 2 (in appropriate units), but quantum fluctuations cause the actual value to differ ever so slightly – by about 0.1% – from 2, giving the “Muon g-2 experiment” its name. This is known as the anomalous magnetic moment of the muon. While a minor deviation is okay, the really big deal is in testing how significantly

Brookhaven Fermilab

Muon g-2 experiment

ABOVE: FERMILAB X3. LEFT: AMERICAN PHYSICAL SOCIETY. RIGHT: CERN

Muons have particle physicists in a spin as two hotly anticipated experimental results deviate from theory. Paul Jackson explains why it matters.

NEXT BIG THING

The muon g-2 experiment took place after an epic journey (below) from Brookhaven, New York to the Fermilab National Accelerator Laboratory in Illinois (arriving, bottom, and installed, right)

experimental results agree with theoretical predictions. The result of the Fermilab experiment has been anticipated for about 20 years. An experiment named E821 – initially run at Brookhaven National Laboratory in Upton, New York, between 1997 and 2001 – created a stir when it produced a measurement of the muon’s anomalous magnetic moment that didn’t agree with the Standard Model. The physics community was curious, but treated the result with a certain scepticism: without any corroboration, and with theoretical physicists divided on how best to calculate the expected value, it was hard

Muons

to get too excited. In 2013 that experiment was literally picked up and moved to Fermilab in Illinois, a journey spanning 35 days and some 5000 kilometres under extraordinary conditions. Then – after three more years of data-taking, and after the international team had checked every part of their experiment – the “unblinding” was performed using two separate values in sealed envelopes, opened simultaneously to ensure they were consistent. This provided the number to input into the calculation, yielding a breathtaking result. The Fermilab result agreed with the earlier measurement, with a slightly reduced uncertainty. The anomaly persists and (see figure opposite) Electrons the significance has grown to the extent that it’s unlikely that this is simply a chance event. There’s some heated debate in the physics community about the Standard model prediction 1:1 exact theoretical prediction

(it’s a tricky calculation) but a team of more than 100 theoretical particle physicists have worked on the current estimate for many years. The result is truly amazing. But there’s more! The LHCb experiment at the CERN Large Hadron Collider has recently published results that also disagree with the Standard Model, and also involve muons. LHCb focuses on collisions of high-energy protons to study the production and decay of particles containing beauty (or bottom) quarks. These quarks combine with the lighter quarks that make up the proton and neutron to form mesons. When a meson containing a b-quark decays, it can follow a huge variety of possible decay chains. One rare method involves the decay of the b-quark to a meson containing a strange quark and either an electron and positron, or the equivalent with the muon (see figure below). The Standard Model predicts that in this rare decay, electrons and muons should be produced equally often, which can be calculated by the theory with very high precision. But recent results show there seem to be more muons than expected! The measurement disagrees with the Standard Model with a significance of 3.1 standard deviations, or about a 1 in 400 chance of it being a fluke. This suggests quite astounding possibilities. A fifth force? One or more new particles? The likelihood that these experiments are just “wrong” is starting to seem far-fetched, and further anomalous measurements are currently under investigation. At some point, the Standard Model could start to resemble a relationship that you know isn’t working but you patch up and cling to anyway, because moving on feels scary and a little painful. There may be a whole suite of discoveries on the horizon that can excite the next wave of scientists, with new technologies and ideas to design experiments that get to the bottom of how to revamp the Standard Model.

PAUL JACKSON is a Professor of Physics at the University of Adelaide. He measures the fundamental building blocks of nature at CERN with the ATLAS experiment, and in Japan on the Belle II experiment, measuring decays of b-quarks. cosmosmagazine.com 25

Just a little

PERSEVERANCE Much of what NASA’s achieving through the Mars 2020 mission – including the historic flights of tiny helicopter Ingenuity – will likely inform future explorations. As Perseverance continues to beam news and views back from Mars, TORY SHEPHERD reports on what’s at stake, and the Australians who are part of the Mars 2020 team.

Master and apprentice, Perseverance took this April 6 selfie with Ingenuity after deploying the tiny aircraft. This image itself speaks of the mission’s technological wonder: it’s 62 individual frames stitched together, captured with a camera called WATSON (Wide Angle Topographic Sensor for Operations and eNgineering) located at the end of the rover’s robotic arm, which ends up out of the picture when the mosaic is assembled. 26 COSMOS MAGAZINE

PERSEVERANCE SuperCam

Navcam

Mastcam-Z

Navcam

astcam-Z

ar Hazcams

NASA / JPL-CALTECH

Front Hazcams

cosmosmagazine.com 27

28 COSMOS MAGAZINE

FEBRUARY 18: LANDING AND WHAT DOES MARS SOUND LIKE? Stunning video shot on Perseverance’s landing day shows the rover plummeting, parachuting and rocketing toward the surface of Mars. “For those who wonder how you land on Mars – or why it is so difficult, or how cool it would be to do so – you need look no further,” says acting NASA Administrator Steve Jurczyk. “Perseverance is just getting started, and already has provided some of the most iconic visuals in space exploration history.” After touchdown, a microphone on the rover doubles down on cool by picking up a remarkable first, recorded on 20 February: audio recordings from the Jezero Crater on Mars. About 10 seconds into the one-minute recording, a Martian breeze is audible for a few seconds, as are mechanical sounds of the rover operating on the Red Planet’s surface.

BELOW: BILL INGALAS / NASA / JPL-CALTECH. ALL OTHERS: NASA / JPL-CALTECH

t was a display of… well, ingenuity. A tiny, 1.8kg helicopter called Ingenuity hitched a ride to Mars on the Perseverance rover. On April 21, it flew – the first powered and controlled flight on another planet. In a sense, NASA was just showing off when Ingenuity spun its rotors against the backdrop of the Red Planet, rose three metres into the air and hovered, then took some photographs, before dropping back down on the Martian landscape. Twice more – on 22 April and again on 25 April – Ingenuity flew, the final time flying about 50 metres downrange from its take-off position at an altitude of about 5 m, for a total flight time of close to a minute and a half. One could dismiss these flights as mere displays – but they’re displays of what’s to come. One day, there might be swarms of these tiny choppers on Mars, scouring the landscape for information – including the possible proof of extraterrestrial life. That’s what Queensland University of Technology’s Dr David Flannery pictures. Flannery is a planetary scientist, and a long-term planner and co-investigator in NASA’s 2020 Mars mission. His PhD was awarded for research into the evidence for life in ancient rocks in Western Australia (WA). After that, he went to work for NASA’s Jet Propulsion Laboratory (JPL) as part of the Mars 2020 team. There, he started working on PIXL – the Planetary Instrument for X-ray Lithochemistry, an instrument to search for ancient microbial life that was proposed by another Australian at JPL, Dr Abigail Allwood. “I translate the expertise I have in ancient rocks,” Flannery says. “For my bread-and-butter research I look at really old rocks, because I’m interested in the early evolution of our planet and life on our planet. “At the moment we’re looking at similar rocks on Mars that are about the same age. “We’re for the first time officially looking for evidence of past life in the rock record of Mars. On Earth we find various lines of evidence for microbial ecosystems that were present and we’ll be looking for the same sorts of evidence on Mars.” As a long-term planner, Flannery’s part of the team that will decide where to send Perseverance. Now Ingenuity can help them make those decisions. It will act as a scout. “In the future we might consider sending more, maybe dozens,” he says. “I think that’s the way Mars will go in the future. A helicopter demonstration like this allows us to test some of the technology. Autonomous flight, communications – a swarm would need to communicate with each other and operate without a human in the loop.

NASA / JPL-CALTECH

PERSEVERANCE

After being dropped out of Perseverance’s belly (top left), Ingenuity sat alone (top right) through various systems tests for several days, before taking its first flight (above middle pair) on 19 April. On Ingenuity’s third flight, on 25 April, it snapped the Mars rover (above, at far left) about 85m away and the rover’s landing site (at far right).

“In the future we could use helicopters like this to scout for us, in new areas that we can’t see from orbit. We can’t drive the rover everywhere. It’s absolutely incredible, and it’s incredible that engineers from JPL could put this together in a short period of time, to integrate it with the mission, deploy it and fly it.” Allwood and Flannery both studied fossil stromatolites in 3.45-billion-year-old rocks in WA’s Pilbara. Allwood proved the structures were stromatolites and therefore evidence of microbial activity. Then she went to JPL and started developing PIXL, which she told ABC News, sits on the rover “like a little six-legged insect”. PIXL can look at rock features as small as a grain of salt and detect chemical elements, searching for signs of ancient life. The NASA Mars 2020 deputy program scientist is another Australian – Dr Adrian Brown. He told the COSPAR 2021 conference on space that finding stromatolites on Mars would “change the mission straight away”. “We would immediately be answering the question of how prevalent life is on other planets. It would be ‘all pens down’.” The role of Ingenuity and future rotorcraft will be to help the rover find candidate sites, and it’s hoped eventually they will be able to grab samples and carry them back to the rover, and to PIXL for analysis. For about seven months, the little chopper was carried 470 million kilometres to Mars in the belly of the Perseverance rover. When Perseverance landed, it released the tiny helicopter in the Jezero Crater, which scientists think was once a flooded river delta. It’s a 45-km-wide basin that is a possible

MARCH 10: SCIENCE UNDERWAY AS SUPERCAM LASER-ZAPS MÁAZ The first readings from Perseverance’s SuperCam instrument arrived on Earth at the French Space Agency (Centre National d’Etudes Spatiales, CNES) operations centre in Toulouse. The data includes the first audio of “laser zaps” on another planet: a rock target (above, middle ) named “Máaz” (Mars in the Navajo language). “The sounds acquired are remarkable quality,” says Naomi Murdoch, a research scientist and lecturer at France’s Institut Supérieur de L’aéronautique Et De L’espace (ISAE-SUPAERO). “It’s incredible to think that we’re going to do science with the first sounds ever recorded on the surface of Mars!” SuperCam is collaborative project of the Los Alamos National Laboratory (LANL) in New Mexico, US, and a consortium of French research laboratories under the auspices of CNES. And Máaz? The Perseverance team has a list of 50 names to use – for starters – that it developed with the US’s Navajo Nation. cosmosmagazine.com 29

APRIL 6: HERE’S THE MARTIAN WEATHER REPORT NASA releases the first weather from the Jezero Crater, pieced together from data from the Mars Environmental Dynamics Analyser (MEDA) system aboard Perseverance. MEDA engineers had first received initial data from MEDA a day after the rover touched down. The data showed it was just below -20°C on the surface when the system started recording, and that the temperature dropped to -25.6°C within 30 minutes. Over the next year, MEDA will provide valuable information on a range of matters that might inform the design of the planned mission to return to Mars to collect samples. MEDA measurements will also provide information to engineers considering future human missions to Mars. 30 COSMOS MAGAZINE

site for Martian microbial life. The crater, which is about the same age as those WA rocks, was chosen from 60 potential sites for stromatolites, and it won in part thanks to what NASA calls its “bathtub ring” – around the rim of the crater are deposits of carbonates, which in turn could indicate the presence of stromatolites. What Ingenuity had to achieve to become a useful part of the search, was flight in a very different atmosphere. Compared to Mars, Earth’s atmosphere is like custard: easy to push against. While Martian gravity is less than half that on Earth, it’s harder to fly in because the atmosphere is 1% of Earth’s, so there’s less to push against. And Ingenuity had to react to its environment on its own because it takes 16 minutes for instructions to come from our pale blue dot – imagine a helicopter waiting that long to be told how to react. It also uses solar power to charge its batteries and to keep it warm enough to deal with the cold Martian nights, which can get down to -90°C. Ingenuity had to be super light, with miniaturised flying technology. It had to have super-fast rotors (NASA says its “specially made carbon-fibre blades [are] arranged into two rotors that spin in opposite directions at around 2400 rpm – many times faster than a passenger helicopter on Earth”). It succeeded. While doing so, it carried a swatch of the same fabric that covered the wings of the Wright Flyer, the aircraft built and flown by Orville

NASA / JPL-CALTECH

50 CM

PERSEVERANCE

A 360° panorama of Mars from Perseverance’s Mastcam, taken on February 24, three days into the rover’s mission.

NASA / JPL-CALTECH

APRIL 20: LET’S MAKE SOME OXYGEN

Find regular Ingenuity and Perseverance updates at www.cosmos magazine.com

The list of firsts for Perseverance grew when NASA announced that an instrument on the rover had converted some of Mars’ thin, carbondioxide-rich atmosphere into oxygen. The toaster-sized experimental instrument is called the Mars Oxygen In-Situ Resource Utilization Experiment (MOXIE). While the tech demonstration is in early days, it could lead to science fiction becoming science fact: isolating and storing oxygen on Mars to help power rockets that could lift astronauts off the planet’s surface. Such devices also might one day provide breathable air for astronauts themselves. Not that anyone could live for long on the amount of gas MOXIE produced in its first one-hour test: about 5.4 grams, according to the instrument’s principal investigator, Michael Hecht of Massachusetts Institute of Technology’s Haystack Observatory. “That’s about enough to keep a typical active astronaut alive for 10 minutes,” he says.

and Wilbur Wright to make the first powered, controlled flight on Earth in 1903. Former US astronaut and unabashed Mars enthusiast Buzz Aldrin, who himself made space history during the 1969 Apollo 11 Moon landing, said “today we watched history occur in real time”. He tweeted his congratulations to NASA and the Perseverance team, saying: “This historic flight of the Mars Helicopter truly is one small step that’ll produce another giant leap for future Mars exploration!” That giant leap might not be very far away. NASA has already given Ingenuity a new mission. After its first four flights – each one more adventurous than the last – NASA’s Thomas Zurbuchen said the little chopper remained “in excellent health”, and that so far its work had been a “resounding success”. Once it fulfilled its job of proving that flight is possible, NASA decided it was time for the next step. Operators will start testing out Ingenuity’s limits, its precisionmanoeuvringabilitiesandaerialobservation capabilities. As Perseverance starts moving towards promising rocky outcrops, Ingenuity’s job is to scout the rover’s targets and potential routes, taking images of inaccessible features, and to continue the search for life outside Earth.

TORY SHEPHERD is an Adelaide-based journalist. Her last feature, about Australia’s race into space, appeared in Issue 90. cosmosmagazine.com 31

For at least 65,000 years, First Nations Australians have understood Earth’s place in the universe, write Kirsten Banks and Duane Hamacher.

SOLAR SYSTEM knowledge of the First AUSTRALIANS

and is celebrated in numerous ceremonies and stories (opposite, as depicted in Daniel O’Shane’s Iluel Kab – Evening Star Dance – from the Torres Strait).

32 COSMOS MAGAZINE

great many names for them, reflecting deep layers of astronomical knowledge.

JOURNEYS ALONG THE SKY ROAD The planets travel along a special pathway in the sky, along with the Sun and Moon. This is the path of the ecliptic, moving along the background stars of the zodiac. Senior Wardaman Law Man Bill Yidumduma Harney refers to the path as Yondorrin, teaching how the cosmic Dreaming track is a road over which the “old spirits”, as planets, walk during their cosmic travels. “Planets making the pathway! Travelling routes, a pathway you could call it, like a highway!” As the planet-ancestors travel along Yondorrin, they act in ways very different to any of the background stars. Uncle Yidumduma teaches that, “the planets come straight across like you and I going on a walk. Up and down, walking backwards, forwards.” Just as

SIMON STONE / ALAMY

The regular path of Venus (above, over Uluru, trailed by Jupiter in the early evening zodiacal dust light) has long been understood,

Have you ever tried to spot a planet in a sky full of stars? If you know what you’re looking for this could be an easy task, or you might make use of a handy sky guide app on your smart device to help point you in the right direction. But Australia’s First Peoples have maintained an intimate connection to the night sky based on 65,000+ years of observation, and this includes a detailed understanding of the planets and their complex motions in the sky. The five planets visible to the unaided eye – Mercury, Venus, Mars, Jupiter and Saturn – are much closer to us than distant stars, and appear to move among the background canopy. Some move quickly, like swift Mercury. Others move at a grandfatherly pace, like distant Saturn. The ancient Greeks called these celestial bodies planetai, meaning “wanderers”. Westerners know them today by their Roman names, but Aboriginal and Torres Strait Islanders have a

INDIGENOUS ASTRONOMY we walk down the street, we might stop, catch up with other people, or even walk backwards for a bit before continuing on our journey. Astronomers call this retrograde motion, which is an optical illusion that happens when we look at other planets from night to night as each planet orbits the Sun at a different rate. All the planets go through periods of retrograde motion, which makes them appear to stop and move backwards for a time, before continuing on their original course.

DANIEL O’SHANE

THE INNER PLANETS Mercury, the closest planet to the Sun, is swift. The Romans named it after their messenger god, as it only appears low in the morning sky for a couple of weeks, then disappears for a month and a half before reappearing in the evening. In Wardaman, Mercury is a little girl named Gowaman who hides away from the threatening actions of the Moon-man. Venus is the brightest planet and third brightest object in the sky after the Sun and Moon. You may know Venus as the Morning and Evening Star, as it can lead in front of the Sun before dawn or trail behind the Sun after sunset. Of all the Aboriginal and Torres Strait Islander astronomical traditions involving the planets, Venus is the most prominent. First Peoples across the world recognise Venus as a Morning Star and an Evening Star. They are seen as the same object but are never visible in the morning and the evening on the same day. In the eastern Torres Strait, elders teach that Venus is called Iluel in the evening, and Gerger Neseur in the morning. Kapua Gutchen Snr, an elder from Erub, teaches a traditional story about a young couple: the mischievous Meb, the Moon man, and the beautiful Iluel, the Evening Star-woman. The lovers have a relationship marred by atkit (jealousy). Meb is jealous of Iluel’s relationship with Lim, the SunMan, as she always stays near him, occasionally brushing along his side. Iluel is jealous of Meb’s relationship with her sisters, the planets, as they wander the heavens together. The lovers come together once a month, when Meb appears as a crescent in the evening. They drift apart as the days pass, but come together a month later. Erub islanders call the conjunction of the two lovers Atkit Meb, meaning “jealous moon”. Yol gu people on Galiwin’ku (Elcho Island) in the Northern Territory have long observed the complex motions of Venus. They note that it spends nearly nine months as a Morning Star, before disappearing for about 50 days and re-emerging as an Evening Star for another nine months. It dips below the horizon again for only eight days before emerging as a Morning Star. The people conduct a sacred ceremony called Banimbirr when Venus rises in the morning sky after disappearing as an Evening Star eight days previously. This ceremony is planned well in advance and people cosmosmagazine.com 33

INDIGENOUS ASTRONOMY YOLNGU

TORRES STRAIT

WARDAMAN

ANMATYERRE

KOKATHA

MURUWARI KAMILAROI

WAILWAN

WIRADJURI

travel from far and wide to attend as Venus ascends into the dawn sky, signalling the location of Burralku, the island of the dead in the east. Elders explain how they count the days to know when it will appear. Western astronomers refer to this cycle as the synodic period of Venus, which lasts for 584 days before repeating.

During the Banimbirr ceremony, dancers hold up a sacred Morning Star Pole, which they use to point towards Venus. It is covered in meaningful designs, as well as beautiful white features dangling from strings. The features represent the rope by which Venus is tied to the Sun. It can be seen in the evening or morning sky as a long, white triangle of light stretching from the horizon into the sky. This is what Western astronomers call zodiacal dust, tiny debris particles scattered around the Solar System. It reaches up into the sky, exactly where you will find Venus as a Morning or Evening Star. In the eastern Torres Strait, Meddy Kaigey, a Komet elder from Mer, teaches that when this light extends high in the sky, it is time to plant bananas and yams. When the light reaches the very top of the sky (zenith), the first rains of the monsoon season (Kuki) will follow a week or two later. This happens in late November and December. The zodiacal light is easiest to see in the Nay Gay season, when the weather is fine, the air is still and the sky is crystal clear.

VENUS LAUGHING Those with a keen knowledge of astronomy will recall that when looking for a planet in the night sky you’re looking for the stars that don’t twinkle. In the Torres Strait, Meriam elders understand this phenomenon, which happens because planets are closer to the Earth and their light is more stable in the atmosphere. 34 COSMOS MAGAZINE

Australia’s First Nations peoples (see map, top left) share an understanding of the planets’ “wandering” patterns, like Mercury (top, in the last three hours of its transit across the Sun in 2019). This includes the concept of retrograde motion, where for us on Earth planets appear to stop and reverse because of their different orbits (top opposite, Mars in diagram and photographed in time lapse with Uranus visible behind).

TOP: ALAN DYER / GETTY IMAGES. LEFT: COURTESY VIVIEN ANDERSON GALLERY, MELBOURNE

ZODIACAL LIGHT

Banimbirr, or Morning Star Poles (opposite, by Malu Gurruwiwi, 1942–2020) are

TOP, FROM LEFT: TTEZEL / FLICKR. SIMON STONE / ALAMY. (COCKATOO) EDUATION IMAGES / GETTY IMAGES

pointed towards Venus during certain ceremonies, the feathers on strings representing the planet’s ties to the Sun and Moon. Kokatha people link the red planet Mars to the redtailed black cockatoo (left).

However, when any star or planet is close to the horizon, its light has to compete with a much more turbulent and dense atmosphere. At this position, these objects are often subject to violent twinkling, which is called scintillation. When Venus is particularly low to the horizon it can twinkle quite a lot, appearing to change brightness and colour. The Kamilaroi and Euahlayi people of northern New South Wales see Venus twinkling as an old man who is laughing to himself after telling a rude joke.

Learn more at www.aboriginalastronomy.com.au

THE OUTER PLANETS Not only are individual planets significant in Aboriginal astronomical traditions, but so too are the relative positions of multiple planets. In Euahlayi traditions, when the planets Mars and Venus come together in the night sky they are seen as the eyes of Baayami, the creator spirit. This conjunction in the sky holds special significance to the Euahlayi people and is linked to a ceremony.

The planet Mars holds special significance in many Aboriginal astronomical traditions. Its reddish colour is described in terms of fire. Anmatyerre people of the Central Desert describe Mars as Iherrm-penh, meaning “something that has been burnt in flames”. It is also associated with animals on the land that have bright red features. Kokatha people of the Western Desert link both Mars and the giant red star Antares with Kogolongo, the red-tailed black cockatoo. Mars and Antares are rivals in the sky. Antares is the brightest star in the constellation Scorpius. Since the ecliptic passes through Scorpius (which is why it is a zodiac constellation), Mars sometimes passes close by. They are both similar in brightness, very red and fight for dominance. Mars is the Roman god of war and Antares means “Rival of Ares”, the Greek god of war. Jupiter is also known for its brownish-red colour. Muruwari people of the Darling River in NSW call Jupiter Wurnda wurnda yarroa. This is an ancestral figure who feasted on roasted yams. Jupiter’s colour is a reflection of the fire used to roast them. In Kamilaroi and Wailwan traditions, Saturn is a small bird called wunygal. In the Western Desert, Saturn (IrukulpinjaI) and Venus (Iruwanja) are brothers, with Jupiter being their dog.

An educational resource for this story is available at www.education. australiascience.tv

KIRSTEN BANKS is a Wiradjuri woman, astrophysicist and science communicator at the University of New South Wales in Sydney. She has over 100,000 followers on TikTok and presented a TEDx talk at the Sydney Opera House in 2019. DUANE HAMACHER is Associate Professor of Cultural Astronomy in the ASTRO3D Centre of Excellence and the School of Physics at the University of Melbourne. cosmosmagazine.com 35

Modern methods for gazing back through deep time reveal crucial tipping points marked by cataclysm, extinction, evolution – and yet our unfathomably ancient planet persists. Truly coming to grips with such vast timescales isn’t easy, but as Lauren Fuge discovers, it could be key to our long-term survival.

36 COSMOS MAGAZINE

I

t’s a warm winter’s morning and I’m standing in a bone-dry creek bed at the precipice of deep time. I’d rolled out of my tent early – dusty and tired and distinctly unshowered – to hike along Enorama Creek in the heart of the arid, ancient Flinders Ranges. Slivers of brittle rock slid beneath my boots as I descended the steep bank to find the only golden spike in the Southern Hemisphere – just five hours north of Adelaide, South Australia. The bronze-coloured disc is in the shade of a river red gum, embedded in the rock at the conspicuous divide between slabs of purple tillite and sandy dolomite. It’s engraved with the cryptic letters EDIACARAN – GSSP 2004, marking it as a Global Boundary Stratotype Section and Point. Colloquially known as golden spikes, these are geological waypoints precisely placed at stark changes in the rock strata, representing transitions between ages. They are records of cataclysms and proliferations, of makings and unmakings – proof of an Earth history too vast to even capture the shape of in my mind. There are less than 100 such markers in the world, so it’s somewhat remarkable that there’s one less than 500 kilometres from my home, tucked in an out-ofthe-way creek down a dirt road.

NOMA BAR

Time travel and tipping points

DEEP TIME

cosmosmagazine.com 37

38 COSMOS MAGAZINE

GOLDEN SPIKE

A Global Boundary Stratotype Section and Point (GSSP) is a reference point on a stratigraphic section which defines the lower boundary of a geologic time scale stage. Once a GSSP boundary has been agreed upon, a “golden spike” (neither golden nor spiked) is laid into the geologic section to mark the precise boundary for future geologists. There are currently 75 ratified spikes; just one, in South Australia, is in the Southern Hemisphere. change, I’m touching the beginning of everything we are, tucked into the rocks like a memory.

S

everal months and a whole mental world away from the Flinders, in a laneway café in Adelaide’s east end, geologist Alan Collins walks me back through a billion years of history. Colour-coded blobs move mesmerisingly across his laptop screen, sliding across a map of the globe. Like the shattered shards of a mosaic, they slam together into supercontinents, break apart, then rearrange into new formations. Each blob represents a tectonic plate, each colour represents the continent it belongs to in today’s world, and each second of the video leaps forward 25 million years. This, Collins tells me, is the first full plate reconstruction of the past billion years, and it’s a key step towards understanding how complex life began. That moment of beginning marked in Enorama Creek – when life worked out how to combine cells and make complicated creatures – is still shrouded in mystery. Why, scientists wonder, did evolution kickstart then instead of at any point in the billion years before? “We have a million hypotheses of why this happened, but absolutely none of them are scientific at the moment,” Collins tells me. “We have no models for what the world looked like.”

TOP LEFT: ROYAL GEOLOGICAL SOCIETY OF AUSTRALIA

The dull, scratched disc is deceptively modest for a monument at the delineation of two worlds, and so small that I have the urge to cover with my palm the moment complex life burst into being. I sink cross-legged onto the sun-warmed tillite and lift my hand to the dusty metal. You know the sci-fi concept of warp drive, where a spacecraft can jump between two distant locations by folding up the fabric of space-time? One moment in the Milky Way, the next in a galaxy a hundred million light-years away? In this creek bed, fingers pressed to the golden spike, time suddenly scrunches up beneath me – and for a brief instant, I’m connected to one of the most crucial climate shifts in history. Seven hundred million years ago, glaciers gripped the Earth from pole to equator in the most intense ice age the planet has ever seen – the first iteration of Snowball Earth. For the full billion years previous, the planet had been slimy and static: volcanoes lay dormant, the atmosphere simmered at low oxygen levels, evolution stagnated with life no more complex than algae, and the climate remained largely in stasis. But when Snowball Earth hit, the world changed – fast. Where I sit in the creek bed, present-day North America ripped away from the Australian continent, opening up a rift valley not unlike those still forming in Africa today. This flooded to become a sea, and when the glaciers retreated and the world abruptly warmed again, life made the leap from single cells to multicellular. The waters of this inland sea soon squirmed and slithered with the first complex life: the Ediacaran biota. Animals emerged and rapidly increased in abundance, size, complexity and diversity, resulting in creatures with the first identifiable heads and bodies, and potentially the first brains and sensory organs. Their soft bodies squelched over sediments that would eventually compress into rock, that as the sea dried up would sink and fold and lift again in the great machinations of this planet’s crust, until I stand on their dredged-up peaks atop nearly a billion years of history. Today, the Ranges have been twisted, buckled and eroded so thoroughly that layers run vertically through mountains and the walls of creeks angle up towards the sky. Years have made unparalleled weapons of wind and rain, slicing through the rock to expose a more ancient time beneath – in some areas of the Flinders, you can travel a couple of dozen kilometres and pass through hundreds of millions of years. Time is thin here; the eons slip in and out of each other. It’s one of the few places where I’ve ever felt close to glimpsing just how immensely old the planet is – just how many generations stretch out behind me, and just how many stretch out ahead. In Enorama Creek, one hand on the weathered disc carefully placed to mark a massive planetary

DEEP TIME

But now, on his laptop screen, we watch the Flinders Ranges begin to fold up out of the Earth. It’s 800 million years ago and the Australian continent is only half there – the south-east corner is completely missing. We’re part of the supercontinent Rodinia still, but as I watch, North America yanks away from the Flinders and skids off around the globe. The inland sea opens up, and as Snowball Earth gathers pace, the years tick away in the corner of the screen – 800, 700, 600 million years ago – water flows in. “We’re now in the Cambrian,” Collins says casually. “It’s possible trilobites and things are swimming around in the oceans now. And we’ve got this big, big continent – this is Gondwana.” Soon North America returns to the rapidly growing conglomerate, and just like that, Gondwana morphs into Pangea: the last supercontinent before the fragmented period we live in today. When a billion years is packed into less than a minute, the tectonic pulse of the planet is visible: supercontinents form, splinter, form again 90 degrees around the globe, and then splinter again. Each cycle lasts around half a billion years and affects the flow of material out of the deep Earth, shifting the upwelling and downwelling zones. This mind-boggling kind of perspective is important not just for pure geological understanding, but to give context to the incredible changes the planet has seen. Many of the elements required by life – for example, the phosphorous that forms the backbone of our DNA – came from the deep Earth. They must have been hauled up to the surface at some point, but there is no big picture understanding of how the planet’s many interrelated systems combined to make this happen. This new geological reconstruction – published in the journal Earth Science Reviews and led by Andrew Merdith from France’s Université de Lyon – is the beginning of just such a framework, showing how the Earth as a whole evolved, and potentially helping scientists quantify and test models about the evolution of life.

The Flinders Ranges were

multicellular organisms on

once a seabed, hardened by time and buckled into

Earth. Spriggina floundersi (below) is one such early

mountains by tectonic forces. The false-colour aerial view

species, dating back to the Ediacaran Period. There

(left) shows the rugged folds of the Vulkathunha-Gammon

is still some debate about where the Ediacaran biota

Ranges National Park.

belongs in the tree of life –

Years of erosion have cut through the rock, revealing

scientists aren’t yet sure if these early fossils represent

impressions including fossils representing the earliest

plants, animals, or something in between.

ABOVE: ESA. RIGHT: SOUTH AUSTRALIAN MUSEUM

In this creek bed, time suddenly scrunches up beneath me – and for a brief instant, I’m connected to one of the most crucial shifts in history.

For Collins, this global plate model is one thread in the pursuit of an all-encompassing Earth systems theory, asking some of the most fundamental questions: How did the planet come to be? Why does it move and breathe like it does? How did life arise? Why is everything the way it is? “This is the stuff that I love,” he enthuses. “This is only really happening in the last five years – people are starting to really see where the links are.” Collins and his team at the University of Adelaide were involved in pulling together the data to build the reconstruction, in conjunction with researchers from France, Canada, China and elsewhere in Australia. cosmosmagazine.com 39

This was fed into a piece of software developed by the University of Sydney. Called GPlates, the software is like GIS – a system for representing data related to positions on the Earth’s surface – but reaches back in time in an attempt to map what the world was like on the grandest possible scale of history: where the plate boundaries were and how they evolved, how continents collided and how they tore apart. Putting this map together involved digging up and scrutinising research from decades past, including evidence for the locations of plate boundaries and how they changed over time. “A lot of it is integrating data that’s been out there for years, bits of chemistry or some paper 20 years ago,” Collins explains. “It’s really just data mining on this whole-Earth scale.” When you piece it all together, he says, you end up with “a horrendous, four-dimensional jigsaw puzzle: three dimensions on the surface, and then it goes through time as well”. In 2017, the collaboration published a full plate reconstruction stretching from 1–0.5 billion years ago, encompassing all the exciting moments such as massive climate swings and the explosion of animal life. Now, the team have added the most recent 500 million years up to the present day – so when Collins hits play on his laptop, a quarter of the planet’s history unspools before me in 40 seconds. As we watch the plates peel out of the supercontinent Rodinia then zip together into Gondwana, I find myself on that same precipice of understanding I felt in Enorama Creek. Balanced on the rim of deep time, I squint into the vast chasm of the Earth’s past, and for an instant I can almost focus all the way down. It’s astounding that science now has the capability to do this – to collect, synthesise and represent data in a way that helps humans understand our temporal location in a vast planetary history. Our brains were arguably not built to deal with scales much beyond our own lifespans, yet geology is now radically extending our abilities to perceive time. But staring so far back into the past doesn’t come easily. “It’s impossible,” Collins tells me. “But there’s loads of games you can play. What I do with primary school kids is talk about toilet paper.” Imagine one sheet of toilet paper is 100 years. If there are 200 sheets in a roll, then a single roll represents 20,000 years. A hundred of those and you’ve jumped back two million years, to when our genus Homo split off from our other hominid ancestors. “Then you can go back and you can keep on playing,” he says. “Once you’ve got a whole building full of toilet papers [30,000 rolls], you’re back in the Precambrian.” 40 COSMOS MAGAZINE

“But even then, it’s all very arbitrary,” Collins admits. “It’s hard to get your head around the timescales.” Many minds have tried to grasp this slippery problem, including palaeontologist Stephen J. Gould in his classic 1987 book Time’s Arrow, Time’s Cycle. “An abstract, intellectual understanding comes easily enough – I know how many zeroes to place after the 10 when I mean billions,” Gould writes. “Getting it into the gut is quite another matter. Deep time is so alien that we can only really comprehend it as metaphor.” These metaphors go far beyond toilet paper, contorting language in attempts to simulate true understanding – for example, imposing the entirety of geological time onto a kilometre, where humanity occupies only the last few centimetres, or onto a 24-hour clock, where we evolve in the last seconds before midnight. A particularly striking metaphor comes from John McPhee, the American writer who coined the term “deep time” in his 1981 book Basin and Range:

CIRCLE OF LIFE

This “clock” represents the major units of geological time and defining events of the Earth’s 4.6-billion-year history. Bjornerud argues that as a metaphor, it is alienating – the fact that humanity appears at the end makes people feel unimportant. Even the notion of “the end” is an optical illusion: the present moment is neither the crux nor final destination of history.

DEEP TIME

“Consider the Earth’s history as the old measure of the English yard, the distance from the king’s nose to the tip of his outstretched hand,” he writes. “One stroke of a nail file on his middle finger erases human history.”

I

’m hiking down a tributary of Arkaroola Creek, right in the centre of the king’s palm. Above me the winter sun glares down, and beneath me lies 700-millionyear-old glacial tillite: a jumbled mix of lavender, reddish purple and pastel grey rock, studded with ice-scoured pebbles and boulders dropped by glaciers during the first Snowball Earth. I’m just outside Vulkathunha-Gammon Ranges National Park, 200 km north of Enorama Creek but along the same spine of mountains. The landscape tells the same story of deep time. Some kilometres back I passed a hilltop capped with buff-coloured rock that was once an ancient reef, home to unusual sponge-like structures that emerged after the great melt 650 million years ago and may, as a small sign quietly notes, be among the earliest signs of multicellular life on Earth. Now, I’m walking on tillite that appears to flow down the creek in a series of frozen cascades. The region is once again transformed today – both ice and shallow sea have vanished, replaced by drought-gripped rock and red dirt. I slip between the precious shade of shrivelled red gums; the black eyes of Sturt’s desert peas blink at me; algae clings to the surface of shrunken waterholes. I climb out of the creek and enter a moonscape of volcanic basalt, formed 830 million years ago when the continents tore apart. As I pick my way over crumbled chunks of rock mottled with green and orange, I’m travelling up the king’s hand, towards his arm and through time. The millennia speed up in my head and the planet reveals its restlessness: rocks move as though they have tides; mountains rise and fall like breaths. Reading the landscape through time reveals not just its age, but the threads that make up the vast story of its history.

Though located on different

many parts of the distant

sides of the planet, these two places – Agios Pavlos

past. These two places are also both geologically

in Crete, Greece (left) and Arkaroola in the

messy: Crete lies above a subduction zone between

northern Flinders Ranges (below) – were created

the African, Aegean and Eurasian plates, and so is

by similar tectonic forces.

pushed and pulled from

Compression can crumple horizontal layers into

many directions, while Arkaroola’s chaotic geology

spectacular folds, often uplifting older time periods

preserves evidence of many different environments over

and offering a glimpse into

more than a billion years.

LEFT: ALAMY. ABOVE: DE AGOSTINI / GETTY IMAGES. RIGHT: ADAM BRUZZONE SATC

Consider history as the distance from the king’s nose to the tip of his hand. One stroke of a nail file on his finger erases human history.

“I don’t think any of us really understand what a billion years means,” Marcia Bjornerud tells me later, in a video call across time and space, oceans and seasons. “But little by little, you start filling in geologic time with stories, and I think that’s where we will understand.” Bjornerud is a professor of geosciences at Lawrence University in Wisconsin, in the US, where she studies rock formation and mountain building. She’s also the author of a slim, powerful book called Timefulness: How thinking like a geologist can help save the world. In our conversation, she mentions two distinct Greek words for time: chronos, which is the straightforward measurement of seconds, minutes and hours, and kairos, which is “time within a narrative”. cosmosmagazine.com 41

G

eologists have been prudently placing golden spikes around the world since 1977, as part of an ongoing project to provide reference points for their colleagues of the future. Like the disc embedded between glaciation and complex life in Enorama Creek, they mark sharp and stable snapshots of when the planet lurched from one chunk of geological time to the next. Some of these boundaries are clear in the rock record; others are based on distinct changes in animal life; all herald transitions in Earth’s history. Near a small town in north-west Tunisia, for example, a golden spike is hammered into a parched, furrowed hillside at a striking red 42 COSMOS MAGAZINE

TECTONIC TIMELAPSE

Snapshots from the first full-plate tectonic reconstruction of the last billion years. White areas represent oceanic crust, while green areas are modelled continental lithosphere, and blue areas are additional present-day continental crust. To create this, geologists synthesised decades of research, including figuring out the locations of mountains (where continents have hit each other) and ocean basins (where continents rifted), as well as the bathymetry of the ocean (related to the locations of mid-ocean ridges, subduction zones and trenches). Scientists think the Earth was once like Mars and Venus – with a rigid outer layer and no apparent plate tectonics – but for a reason they don’t yet understand, something shifted, plate tectonics was kickstarted and everything changed.

LEFT: ALAN COLLINS X3

“That’s what really makes geological thinking different,” Bjornerud says. “We do want to quantify time, but the power of geology has been to recreate these narratives of earlier ecosystems and tectonic events on Earth. That’s where you start developing a sense of how long a billion years is.” Reading the land in four dimensions can give us a consciousness of what she calls timefulness: a “cleareyed view of our place in time, both the past that came long before us and the future that will elapse without us”. It’s important to understand because we too live in geologic time: “We’re part of this continuum – we have deep roots evolutionarily in the tree of life.” As I walk the remnants of vanished worlds in Arkaroola Creek, where the ebbs and flows of the landscape are visible, I’m keenly aware of my own deep roots in the Earth – as an organism not separate from or above the rest of nature but inextricably linked to the ancient, almost alien animals that teemed in the shallow seas of the Flinders. Geology confirms how deeply we are bound to the planet itself. As writer Robert Macfarlane describes in his epic work of literary non-fiction Underland: A deep time journey, humans are in fact part mineral beings: “Our teeth are reefs, our bones are stones – and there is a geology of the body as well as of the land. It is mineralisation – the ability to convert calcium into bone – that allows us to walk upright, to be vertebrate, to fashion the skulls that shield our brains.” With this knowledge in my minerally fortified mind, the boundaries between living and non-living begin to blur; the illusion of separation breaks down. “Dazzled by our own creations,” Bjornerud writes, “we have forgotten that we are wholly embedded in a much older, more powerful world whose constancy we take for granted.” Standing on the king’s palm and gazing back down his arm, I wonder what the enormity of time can teach us about the planet’s future.

DEEP TIME

layer of iridium-rich sediment – just a few millimetres thick – sandwiched between two dark layers of clay. This rare metal was strewn across the world 66 million years ago – as debris from the asteroid strike that wiped out three-quarters of the Earth’s species. Below the iridium layer: dinosaurs. Above the iridium layer: the mammalian rise to dominance. The golden spike in Enorama Creek doesn’t mark a mass extinction, but it does mark a massive change: Snowball Earth. Weird climate events like global glaciations are interrelated with both plate tectonics and evolution. “Just after the first Snowball Earth is when we start to see a lot of chemical evidence of eukaryote cells filling up all the ecological niches,” Collins explains. “Then you get multicellular creatures start to form.” This particular era is also when oxygen in the atmosphere increased dramatically for the first time in a billion years, roughly reaching the 21% that allows us to breathe today. “That’s because life is going,” Collins says. “Oxygen is one of the few elements that isn’t coming directly out of the Earth – it’s coming from photosynthesis.” But life could only proliferate and photosynthesise because essential nutrients were ground out of rocks by glaciers and washed into the seas. These floods caused bacteria to bloom and churn out oxygen, which in turn helped the water absorb the nutrients, which allowed bacteria to churn out even more oxygen. And so the world turned on and on, until the first animals wriggled through warm waters, dinosaurs reigned and fell, and primates began to chip tools from stone. These vital floods of nutrients were likely the result of Snowball Earth – “glaciers are incredibly good at eroding down mountains,” Collins notes. Geology is also suspected to have caused the massive ice ages in the first place, with large-scale weathering of rocks locking away carbon dioxide and cooling the atmosphere below freezing, shattering a billion years of climactic stability. Plate tectonics even helped us escape the ice’s grip, as volcanoes formed,

While plate reconstructions

in the Endicott Arm Fjord

can reveal the planet’s dynamism by packing billions

in Alaska) but carving out the fjords themselves.

of years into seconds, evidence of the Earth in

Similarly, volcanoes (below) are constantly cycling

motion is all around us. The rock cycle is a current

material from the planet’s depths up to the surface,

affair. Glaciers flow under

forming brand new rocks

gravity like rivers of ice, acting as powerful forces

as lava cools.

on the landscape – not only gouging striations into the rocks (as pictured at left

ABOVE: WOLFGANG KAEHLER, RIGHT: NERY MEJIA / GETTY IMAGES

This new ability to look deeply into the past can help us pinpoint the moments at which the planet tipped – where everything changed.

spewed out greenhouse gases and sent temperatures skyrocketing again. Models of the planet’s surface through time, like the one Collins helped build, are key to understanding what was happening geologically in the lead-up to Snowball Earth, and thus give context to the radical evolutionary changes that followed. But perhaps most importantly, this new ability to look deeply into the past can help us pinpoint the moments at which the planet tipped – where something shifted, the Earth’s systems responded, and everything irrevocably changed. Now, more than ever, these past tipping points are vital to understanding the edge we find ourselves teetering on today. cosmosmagazine.com 43

44 COSMOS MAGAZINE

evolution as we rearrange species across continents and eliminate many more. “What signatures our species will leave in the strata!” writes Macfarlane in Underland. “We have become titanic world-makers, our legacy legible for epochs to come.” Soon, the sedimentary layer of the Anthropocene will be filled with microplastics fossilised into the bodies of zooplankton and the glacially paced atomic pings of buried nuclear waste, decaying over tens of thousands of years – and compacting down to a ribbon of history about as thin as the king’s fingernail, reminiscent of the apocalyptic stripe of iridium in Tunisia. As Elizabeth Kolbert writes in The Sixth Extinction, if civilisation ended today, in 100 million years all “the great works of man – the sculptures and the libraries, the monuments and the museums, the cities and the factories – will be compressed into a layer of sediment not much thicker than a cigarette paper”. We are now not just part of the grand geological narrative of the Earth but directly impacting it, transforming systems far bigger and more complicated than ourselves – with repercussions for generations to come. In Timefulness, Bjornerud names it “temporal illiteracy”: “We are navigating recklessly toward our future using conceptions of time as primitive as a world map from the 14th century, when dragons lurked around the edges of a flat Earth.” Truly understanding the Anthropocene requires us to think on vastly different timescales than we’re

LEFT: SUMIKO SCOTT / GETTY IMAGES

A

s far back as 1873, Italian geologist Antonio Stoppani recognised humanity’s activities as a “new telluric force which in power and universality may be compared to the greater forces of Earth”. But our dominion over the Earth then is nothing compared to now. Today, our surging population and insatiable industrial metabolism are outgunning the planet’s own forces. We have become the dominant influence on the climate and environment, casting aside the stability of the Holocene and driving ourselves into a planetary epoch of our own making: the Anthropocene. It’s no small thing to redefine a geological era, but the rocks tell us it’s true. The dramatic boundary in Enorama Creek represents a rift in normality that kickstarted the whole complex tree of life – and now that we are turning up the heat ourselves, it too is being hardened into the rock record. Since the Industrial Revolution, we have scattered soot across the planet and relentlessly stirred in radioactive elements, inconceivable mounds of plastic, pesticides, excess nitrogen and phosphorous, billions of skeletons from livestock, and enough concrete to spread a kilogram over every square metre of the Earth. Each year mining shifts three times more rock and dirt than all the world’s rivers, and humans are reconfiguring the course of

DEEP TIME

used to. You can imagine a year, or ten, or even a century – but beyond our parents’ parents or our children’s children, the details fuzz; the imagination fails. The geologic record is perhaps the only thing that can give context to our current temporal location. “Understanding the magnitude and the rates of changes in the past is really all we have to go on to know how serious our predicament is now,” explains Bjornerud. “By almost all measures, the rates of change in the last century or so are almost unparalleled in the geologic record.” Geoscientists and ecosystem scientists feel a deep, existential sense of alarm, she notes, because they, more than anyone, recognise the analogous tipping points in the past and the terrifying nonlinear responses that can result. Bjornerud hopes we can drag ourselves back from this edge by listening to the warnings of deep time. “All of those moments of transition from one geochemical regime to another, or one climate system to another, have been times of great upheaval and long-term instability before Earth settled back into a new equilibrium,” she explains. In some sense, this shows remarkable resilience, promising that the planet itself will survive our negligence and our malice. “There’s reassurance in seeing that the world has been through a lot,” Bjornerud says. “There have been terrible mass extinction events, occasional meteorite strikes – and yet, overall, it’s a very robust place. There has never been a moment where life was completely extinguished.” And yet more than 99% of all life that has ever lived on this planet is now extinct. As we hurtle along our current path, we appear keen to add ourselves to this statistic. “At its best,” Macfarlane writes, “a deep time awareness might help us see ourselves as part of a web of gift, inheritance and legacy stretching over millions of years past and millions to come.” Deep time may seem to offer a dangerously false comfort – that our behaviour doesn’t matter when

While some rocks appear

and water levels present

interchangeable to many people, others are windows

at each layer. The Rainbow Mountains in China’s Zhangye

to earlier times. In Arizona’s Painted Desert (centre), the

Danxia geopark (below) tell a similar story of a watery

Blue Mesa Member exhibits thick and colourful bands,

origin, while the sandstone waves of Arizona’s Vermilion

which tell stories of an

Cliffs National Monument (far

ancient river system that wound through the landscape

left) plunge us back into the Jurassic period, when winds

over 200 million years ago, and detail the mineral types

forced the migrations of sand dunes across desert.

ABOVE: ARTERRA, RIGHT: KITTISUN KITTAYACHAROENPONG / GETTY IMAGES

You can imagine a year, or ten, or even a century – but beyond our parents’ parents or our children’s children, the details fuzz; imagination fails.

our species will vanish in the blink of a geological eye. But perhaps instead we could use it to recognise that what we are now urgently trying to save is not the planet – it is ourselves.

T

he Flinders Ranges have been home to the Adnyamathanha people for at least 49,000 years. While geology is just beginning to construct a deep time consciousness through rebuilding the stories of past landscapes, Indigenous cultures have always seen themselves embedded in a larger planetary narrative. cosmosmagazine.com 45

46 COSMOS MAGAZINE

even an imposition on the landscape, such as when we squeeze all of geological history into a single day where humans arrive on the scene mere seconds before midnight. By embedding people within a timeless narrative in a place they have forever lived, Indigenous traditions underpin an inseparable relationship with the Earth, right here, right now. Perhaps recording time is almost unnecessary; what matters most is the present. Even for the Western world, Fletcher suggests, quantifying the deepness of time – both into the past and into the future – may be less important than recognising and fostering this fundamental connection. He warns that if we view time as a linear history of events, we might think we can simply “fix” a mess created in the past and move on. “What after then?” he asks. “We can just take our foot off the pedal? No, it’s about that constant relationship development. We’ve got to start treating the Earth like a family member.”

B

efore standing in Enorama Creek with a billion years folding up beneath me, before the reconstructed plates slid under my gaze at 25 million years per second, before I learned of Snowball Earth or timefulness or how the stroke of a nail file can erase human history, I found myself at an Adnyamathanha engraving site in a

LEFT: WOODSTOCK / GETTY IMAGES

Modern dating techniques place Indigenous Australians on this continent for at least the last 60,000 years, but as Michael-Shawn Fletcher – a Wiradjuri man and physical geographer at the University of Melbourne – tells me, “according to our understanding, we’ve always been here”. “This linear notion of a sequence of events in time doesn’t exist – stories of the past are wrapped up into understandings of the present,” he says. “The agents that made landscapes and Country are still very much with us today, and they need to be serviced and understood and respected.” The land is seen as thoroughly alive, breathed into being by the creatures and the humans who inhabit it. People are strongly influenced by the geology, topography, flora, fauna and climate, all of which feature in stories that act as guiding principles for existing as an inseparable part of the landscape. Whatever happens to the land happens to the people, and whatever happens to the people happens to the land, resulting in a very different kind of responsibility to the natural world. “There’s no imagining of the landscape or Country without people,” Fletcher says. “In the geological sense, by placing everything on a continual timeline, you place yourselves in the world differently – it almost creates a transience.” In Fletcher’s opinion, the problem lies in viewing our species as non-permanent and unimportant in Earth’s linear scheme – perhaps

DEEP TIME

sunbaked gorge, balanced once again on the edge of deep time. I was staying with an Adnyamathanha family, who brought me to Red Gorge in the mountainous corridor between the great salt lakes of Torrens and Frome. Far south down the same spine of peaks, the golden spike waits for me to find it; north, the glacial cascades of Arkaroola Creek stand frozen in time. But Red Gorge holds a different record of the past: galleries of rock engravings thought to be four times older than agricultural civilisation. Standing on the shifting pebbles of the bone-dry creek bed, I squint up at the cliffs of deep red and grey rocks that spill up into the pale blue sky. Then my gaze snags on a dark mark chipped into the rock – head, legs, pointed tail – and a picture suddenly emerges: a goanna. A new depth to the world falls into focus as my eyes flick from rock to rock. Animals and prints leap out from what a moment ago had seemed totally inert landscape – lizards and emu footprints, echidnas and snakes, kangaroo tracks stalked by human prints. Medicine men and women are depicted with huge eyes and staffs, and suns are circles with long rays reaching out in all directions: visual echoes of the soft, symmetrical bodies of the Ediacaran biota. The engravings multiply the longer I look, stretching 20 metres above my head. Though dating is difficult, I’m told that some are thought to be more than 45,000 years old. One of the most stunning is a series of human footprints, chiselled into boulders stepping up the banks of the creek. They trace the path of an invisible figure as it leaps up, up, up the rocks – light, agile, completely at ease in the landscape. But it’s when I spot a human handprint that I feel time contract. The engraving is just a shallow imprint in the iron-coloured stone, surrounded by depictions of snakes and kangaroos, but the

The region around Karijini

Kurrama and Innawonga

National Park (left) in Western Australia began to form 2.5

people for at least 20,000 years. In New South Wales,

billion years ago from iron-rich sediments on the seafloor. Ever

this sandstone formation (opposite) is on the traditional

since, this banded ironstone formation has been tortured

lands of the Gadigal people of the Eora nation, while South

by the slow movements of

Australia’s Red Gorge (below)

the restless Earth. Karijini is a place of deep time in

has been a place of deep cultural significance to the

more ways than one; it has been home to the Banyjima,

Adnyamathanha people for nearly 50,000 years.

ABOVE: AUSCAPE / GETTY IMAGES. RIGHT: LAUREN FUGE

Standing on the shifting pebbles, I squint up at the cliffs of deep red and grey rocks. Then my gaze snags on a dark mark chipped into the rock.

fingertips are outstretched as though someone is pressing into the rock from behind. Instinctively, I lift my own hand and gently fit my fingers into the chiselled grooves. It isn’t like the golden spike in Enorama Creek, like a warp drive transporting me back through time – it is, instead, as if this person stands here with me in this gorge, as present today as ever, hand extended to help.

LAUREN FUGE is a science journalist at Cosmos. Her last feature for the magazine, on eDNA sampling, appeared in Issue 90. cosmosmagazine.com 47

DUDE

WHERE’S MY FLYING CAR?

JOBY AVIATION

The Jetsons cartoons gave the boomer generation a vision of seemingly magically powered flying vehicles, delivering George Jetson to his office, wife Jane to the mall (no sexism there) and the children to school. It all seemed to work so well – if ludicrously far-fetched. Are we any closer? MARK PESCE wonders if aero-autos are finally ready for takeoff…

AERO AUTOS

B

acked by billions in venture capital and a recent IPO, one startup aims to have its flying taxi on the market in three years. While they may be ahead of the pack, they’re not alone. Is this the decade we finally get our Jetsons car? Themostobviousrealitycheckdrawsonourexperiences around the original flying car – the helicopter. Helicopters are really loud. They transit CBD skylines every day, and from 100 metres a launching helicopter has a volume of 90 decibels – about the same as a power lawn mower. Multiply that by hundreds of thousands, and it’s immediately apparent that a world full of flying cars would be deafening. Conversation in public would become impossible. Birds, already adapting their song to the higher ambient noise levels in urban areas, would fall silent, unable to compete. We wouldn’t be able to hear ourselves think. The Jetsons’ flying car, with its soft and satisfying electronic putt-putt-putt sound, is iconic, but right here right now a quiet flying car looks like a physical impossibility. To keep a heavy bit of kit

airborne requires the movement of lots of air – either through propellers or jets. Even if an aircraft were to completely eliminate engine noise (and that day is coming) it would still be pushing a lot of air around, and moving air is sound in its rawest form – a wave of compression through the atmosphere. So a quiet flying car might need to rely upon some sort of magical “anti-gravity” technology not even glimpsed in our wildest predictions of physics. Unlikely. Even if we could solve the noise problem (give all the people and animals noise-cancelling headphones to wear?), we’d immediately run into another problem: scale. The skies over any Australian city hold only very few flying objects, measured in the tens, or, at the most, the low hundreds. Managing even that number of aircraft requires fully crewed air traffic control centres scattered around the country. Presuming a one-to-one substitution of flying cars for ground vehicles – because, of course, everyone would want one – there would soon be hundreds of thousands of flying cars above our city skies every morning and every evening.

Meet the Joby S4 eVTOL. Range: 250 km. Speed: 300 km/h. Power: 100% electric. Joby Aviation announced in February that they plan to have 100 in service as sky taxis by 2026. cosmosmagazine.com 49

The weight and size of the batteries needed to get an aircraft airborne made electrically-powered flight the Holy Grail of 21st century aviation. 50 COSMOS MAGAZINE

An educational resource for this story is available at www.education. australiascience.tv

Joby Aviation’s sky taxi (above left) has already taken flight, but it is being rapidly pursued by a squadron of rivals, like Archer’s two-seater demonstrator (above) – all battery powered.

decade-long research and development efforts that led to the aircraft sitting on a landing pad behind him. It’s an aircraft that looks like it has more in common with a $2000 UAV – a drone – than anything you’d see in the skies today, with six large propellers mounted above the aircraft, but parallel to the ground, just as they would be on a drone – or, for that matter, the main rotor of a helicopter. About 95 seconds into the video, something extraordinary happens: the propellers begin to spin, as the aircraft slowly powers up. Although you can see Bevirt’s hair being tossed around as the propellers send a wash of air in his direction, he continues to speak in relatively measured tones. Within 15 seconds, that aircraft has risen vertically above the landing pad, while Bevirt continues to speak. In terms of live demos, it’s as impressive as anything Steve Jobs ever came up with; in a single stroke, Bevirt shows that Joby Aviation has created an aircraft that’s both quiet and has VTOL – vertical take-off and landing capabilities. All of the best qualities of a helicopter, with none of the drawbacks. Although mounted on a fixed wing, those propellers themselves are not fixed in place. Once the aircraft has attained sufficient altitude, they can rotate 90 degrees, facing forward, just as you’d see on a normal propeller-driven aircraft. That gives it both excellent

THIS PAGE, LEFT TO RIGHT: JOBY AVIATION. ARCHER. OPPOSITE PAGE, FROM TOP: LILIUM. KITTY HAWK. NFT INC

All drivers know that, at best, other drivers on their roads can be inattentive – at worst, downright reckless. Drivers tolerate that risk where a collision means little more than a prang that can be buffed out. But even a glancing blow at speed and altitude would likely create multiple fatalities as both vehicles fell from the sky, crashing into the dense cityscape below. Given the number of prangs on an average day in our cities, our flying-car-filled skies would become a shooting gallery, raining carnage down onto an undefended population. Operating in such a crowded and dangerous environment may simply be beyond the capacity of even the best pilots. Although millions around the world hold flying licences, all of them are taught to operate aircraft within far less crowded environments than those that will accompany the introduction of flying cars. A pilot does their utmost to continuously scan the volume of space they’re operating within, maintaining awareness of all the aircraft (and weather conditions) that could force them into a rapid reaction. Make that a hundred times harder – as it certainly would be during peak hour – and it falls so far beyond the cognitive capabilities of any human being as to make it effectively impossible. Pilots would never be able to maintain the awareness they need to guide their craft safely from takeoff to landing. Despite all of these fundamental roadblocks, this year looks set to mark the birth of a realistic flying car. Toward the end of February, super-secretive startup Joby Aviation unveiled the first model of its own “flying taxi” in a YouTube video narrated by the firm’s founder, JoeBen Bevirt. The video starts off normally enough, with Bevirt talking about the

AERO AUTOS

range – more than 250 km – and a top speed of well over 300 km/h. The final kicker: just like a drone, it’s battery-powered, and 100% electric. The weight and size of the batteries needed to get an aircraft airborne made electrically-powered flight the Holy Grail of 21st century aviation. For 120 years, energy-dense petroleum fuels have been the only real option to generate the necessary thrust. Advances in electric vehicles have come to the aid of the flying car: the same batteries that make electric vehicles cheap and reliable make it possible for Joby Aviation to create an electric flying taxi. They, and other flying car ventures like Archer Aviation, Kitty Hawk and Lilium Jet, could crowd our skies with quiet(er) flying cars rs. A recent reporrt on Advanced Air Mobility from consultancy LEK noted n more than 200 similar designs in development, with w 30 seeking FAA flight certification in the US. Rep port author Natasha Santha reckons flying taxis “will n not be commonplace globally in the However, the industry has tremennext five years... H and deliver services at the cost dous potential to scale s of a taxi today at the fraction of the time.” Could these n new aircraft es? The panreshape our citie demic has seen the rise of the “supercommute r”, travelling more than three ho ours each way to reach the office, doing so only a few times a mo onth. Flying taxis could make su uch journeys

Coming soon to a taxi rank near you? The Lilium Jet’s first prototype (above) flew in 2019; Kitty Hawk (left) recently revealed their plans for a single-seat electric vertical takeoff and landing (eVTOL) aircraft; ASKA (below left) plans for a hybrid eVTOL that works as an aircraft and ground car.

fast, and cheap enough that flying becomes the obvious choice. With the urban advantage alread dy eroded by high-speed broadband, we might see a new w generation of rural residents, each with their own landing l pad, ready to fly to the city at a moment’s moment s notice. not “For the regional market,” Santha says, “costs could be as low as around 40 cents per km... materially changing the transport landscape.” What this means for air traffic control remains an open question. Santha warns that lots of flying taxis create “another set of barriers, which are related to how we can integrate larger volumes [of air traffic]... moving to remote and autonomous piloting”. In the long-term, a “fly-by-wire” solution similar to that on commercial aircraft could see these flying cars piloted by artificial intelligence. Will that be enough to avoid mid-air prangs? Look to the skies for the answer.

Have you seen Cosmos Weekly? Our new e-publication, delivered to you each Friday, has features like this from the magazine journalists you know and love, along with new recruits reporting from around Australia and the world. All the news, with more of the science. Visit www.thecosmosweekly.com to read more.

MARK PESCE is a former judge on ABC’s The New Inventors, the author of seven books and host of podcasts “The Next Billion Seconds” and “This Week in Startups Australia”. This story first appeared in Cosmos Weekly on May 14. cosmosmagazine.com 51

MIND

READERS

52 COSMOS MAGAZINE

O

ne afternoon in the 1980s a small boy sat in a house in Hyderabad in southern India watching television. There wasn’t much on but one show had captured his attention. It was Star Trek, and on that particular afternoon, Dr Spock was bent over a prostrate man. The man was an intruder on the Starship Enterprise trying to warn the crew of danger, but whenever he tried to speak he writhed in pain. Spock puts his hands on the man’s temples and says, in a mesmerising voice, “Open your mind. We move together, our minds sharing the same thoughts.” This was, as any Trekkie will know, the Vulcan “mind meld”, which Spock used to seamlessly access the man’s thoughts and learn of a dangerous machine. That little boy was exceptionally bright, won a scholarship to study in the US and is now co-director of the Centre for Neurotechnology at the University of Washington. His name is Rajesh Rao and he’s had a fixation on the mind meld ever since, because he thinks if we could invent something just like it we might solve a fundamental problem with the design of humans.

MARK STONE / UNIVERSITY OF WASHINGTON

What if mental telepathy was not just a science fiction concept, but as achievable as pulling on a cap and plugging in? PAUL BIEGLER taps into the team of scientists in the US who are sharing their thoughts on the future of mindsharing communication – in more ways than one.

NEUROENGINEERING

cosmosmagazine.com 53

Rajesh Rao imagines moving his hand (below left) and his remote colleague, Andreas Stocco (below right), gets the thought message to drop a finger onto a keyboard. Game on at the University of Washington.

to excite hardcore gamers. A pirate ship was lobbing rockets at a city and Rao had to shoot them down with a cannon, which he did by moving a cursor into a blue square on the screen. At this point, however, any similarities with a kid’s video game ended. Rao was wearing a cap studded with scores of electrodes that lit up red. This was an electroencephalogram, or EEG device, which measured the rhythmic pulsing of Rao’s neurons, something we know as brain waves. Why did Rao need all the high-tech kit? Because his job was to move the cursor with just his thoughts. Rao focussed hard and imagined moving his right hand upwards. Suddenly, there was a shift in the wave pattern on the EEG monitor, which the computer recognised as a command to move the cursor. Rao concentrated harder and, using only his mind, managed to coax the cursor into the blue square. But the cannon didn’t fire – something else had to happen first. Across campus another man was sitting in an office chair, a tight bathing cap on his head. This was psychologist Andreas Stocco, Rao’s long-time collaborator. Stocco is usually animated and speaks quickly in the accent of his native Italy. But now he was subdued. He had been cut off from the world by wearing noise-cancelling earphones and was staring at a blank wall. His right forearm, strangely passive, lay on an arm rest, hand suspended so his middle finger dangled just above the space bar of a keyboard. You see, Stocco, not Rao, was going to fire the cannon. But how? The answer lay in a curious, doughnut-shaped object positioned over the left side of

UNIVERSITY OF WASHINGTON

“Language is the main modality of communication and we have to use our body to express our thoughts,” says Rao. “So speech is all about controlling your vocal cords and your tongue, using muscle control. Same thing with writing. You have to use your hands to write or type. Brain to brain communication would be eliminating that bottleneck.” That’s right: in Rao’s world not being able to get thoughts straight from your own mind into someone else’s is a handicap. If we could only bypass the clunkiness of talk and text, all manner of things might be possible. Let’s say you’ve got a brilliant mathematics professor whose teaching sucks – wouldn’t it be great if you could just transfer the calculus from their brain into yours? Rao is one of a handful of scientists working on a brain-to-brain interface to solve this very problem. It is a challenge right on the limit of our understanding of neuroscience but, incredibly, Rao has succeeded in linking human brains to collectively solve a task. And other scientists are being funded by the Defense Advanced Research Projects Agency (DARPA), the secretive research wing of the US military, to extend the technology to soldiers on the battlefield, for whom an ability to share enemy intelligence with their thoughts would be a distinct advantage. The task is, put simply, to use science to make a telepathy machine. But how on earth would you do that? To understand, we need to travel back to a summer morning in Seattle in August 2013. In a room at the university, Rao was ensconced in a leather recliner playing a video game, the specs of which are unlikely

54 COSMOS MAGAZINE

TOP: MARK STONE / UNIVERSITY OF WASHINGTON X2. RIGHT: JACOB ROBINSON

NEUROENGINEERING

Stocco’s skull. The anatomical detail is important, because just below the doughnut was Stocco’s left motor cortex, which controls movement in his right hand. The doughnut was a transcranial magnetic stimulation coil – TMS for short – which creates a magnetic field to induce a tiny electrical current in the brain, just enough to fire neurons. It had been calibrated precisely so that, when it switched on, a single muscle in Stocco’s arm moved. That muscle was the extensor carpi radialis which lifts the hand. When Rao imagined moving his own hand, it sent a signal across the internet that pinged the TMS device and lifted Stocco’s hand, which then dropped onto the space bar. The cannon fired and, presto, shot down the rocket. It was a simple movement with momentous meaning. This was the first ever demonstration of a human brain-to-brain interface and had addressed, albeit in basic form, part of Rao’s irksome bottleneck. Rao’s thought had moved Stocco’s hand without any need for cumbersome speech or troublesome text. There was a tsunami of media interest, but also criticism. “People said, ‘Okay, that was great in terms of sending information, but where is the second person’s role? The second person’s role is just to provide a hand’,” says Rao. Those jibes, he knew, were on the mark. Wasn’t Stocco, after all, just a marionette, his limb jerked periodically by the digitised thoughts of a puppetmaster? For an invention to even approach a mind meld you need two things. You need to “read” the thoughts of the transmitting brain but you also have to “write” them onto the neurons of a receiving brain. Rao assembled a fresh team with a new goal; they were going to “write” a thought onto someone’s brain, not a string-pulling Svengali in sight. After a number of experiments they settled on a design based on the video game Tetris. The aim in Tetris is to get awkwardshaped blocks at the top of a computer screen to drop

Neurotechnology next? Stimulus in the receiver’s cap would recreate an image from the sender’s brain.

into a vacant spot in a line of blocks below. The team fitted psychology graduate Heather Wessel and undergrad Savannah Cassis with EEG caps to play the game. The women had to make a single decision. Should I rotate the blocks so they fit in the empty spot? If the answer was “yes” they looked to the left of the screen where a strobe light dazzled them. But the dazzle wasn’t random. It was timed to elicit a unique brain signal on the women’s EEG. That brain signal shot along the internet cables bundled behind the lab’s walls to another room where psychology graduate Theodros Haile was sitting. The signal would write a “yes” on Haile’s brain. But how? Haile had a TMS coil strapped to the rear of his skull, over the part of the brain that perceives vision, the occipital cortex. The signal triggered a magnetic

Neuro-Tetris anyone? Heather Wessel (top left) sends a thought stimulus to Theodros Haile (opening pages) to manipulate a simple puzzle game, where blocks must be correctly slotted (top right).

cosmosmagazine.com 55

MRI scans (bottom) show the letter “M” faithfully depicted in the occipital cortex. The US Department of Defense is funding research that would allow soldiers on the ground to be sent “brain messages” of threats hidden from their viewpoint (below).

“If your teammate sees a bad guy, you can see that bad guy… to give you a complete view of the battlefield.” 56 COSMOS MAGAZINE

detailed proposal to secure the DARPA funding and it was during that intense period he received something auspicious in the post. It was a birthday present from his brother – the video game Call of Duty: Modern Warfare. The game was a welcome distraction and Robinson fired it up pronto but, within a few minutes, his character was dead. Fortunately, though, the game has a reanimation feature where you come back to life with some extra cool tech. “What this neurotechnology allows you to do is to see everything that your team can see,” says Robinson. “So if your teammate sees a bad guy behind a wall, you can see that bad guy behind the wall. And so everybody shares that same sensory experience to give you a complete view of the battlefield.” It was, says Robinson, a coincidence, because that feature was spookily close to what the DARPA N3 program hopes to produce. Of growing importance in modern warfare is the unmanned aerial combat vehicle, or combat drone. Drone operators sit at a computer station and need to process reams of information. They must identify targets and plan flight paths, deploy missiles and have a clear understanding of the location of personnel of all stripes. Information comes from systems onboard the drone and from soldiers in the field, some of it verbally though headphones and some visually on the monitor. There is a lot going on. What if the process could be simplified? What if, just like Call of Duty, the drone operator could receive a stream of “percepts” directly from other brains that convey all the required data about an enemy? In 2019 Robinson put the collective shoulder of his team to the wheel. Their first challenge was to “read” a brain with sufficient resolution to capture the richness of a thought – say, the presence of a tank. So, what happens in a soldier’s brain when they see a tank? The action happens in the vision centre of the occipital cortex, which has a peculiar trait called retinotopy. Let’s say you see the letter “M” out there in the world. It actually gets mapped as an upside down “M” on the visual cortex. Literally. If you do a functional MRI scan the active brain cells trace out the letter so faithfully it looks like the occipital cortex has been branded with an “M”. See a tank and it will be reproduced similarly on

FROM TOP: US ARMY. US NATIONAL LIBRARY OF MEDICINE

pulse that produced a sensation for Haile few of us will ever have. “It feels like there is a little flash even though there is nothing in front of you,” says Rao, who has sat in the receiver’s chair but still struggles to explain how it feels. “You could be staring at a blank wall, but it may be that you’re seeing a little blob extend in a particular orientation.” That flashing blob was a “phosphene”, from the Greek phos meaning “light” and phainein meaning “to show”. A bit like telepathic morse code, the phosphene told Haile – who was playing the Tetris game but couldn’t see the crucial bottom row – to rotate the blocks, which he did using his thoughts. The blocks duly turned and fitted snugly into the gap. It was a Tetris-busting collaboration the team dubbed BrainNet when it was published in Scientific Reports in 2019. BrainNet is an impressive achievement but still feels a long way from a mind meld. For a start, there is a heavy reliance on context. Haile, for example, needed to know the flashing blob in his head meant “yes”, which is nowhere near getting thoughts transplanted. It is also a long way from what DARPA is aiming for. The research wing of the US Department of Defense, DARPA is developing something called Next-Generation Nonsurgical Neurotechnology, or N3. In short, it wants wearable, “man-portable” brain devices that help soldiers do their job better – without surgery. DARPA has bestowed US$26 million on a research program led by Jacob Robinson, a neuroengineer and associate professor at Rice University in Houston, Texas. As you can imagine, Robinson had to write a

NEUROENGINEERING

BRAIN POWER

NEURALINK

Early this year, controversial techbillionaire Elon Musk stunned the world once again with his announcement – on the private social media app Clubhouse – that his startup Neuralink had plugged a monkey’s brain with a wireless implant enabling the monkey to play video games with its mind. In the Clubhouse chatroom, Musk told listeners: “You can’t see where the implant is and he’s a happy monkey. We have the nicest monkey facilities in the world. We

want them to play mindPong with each other.” The announcement was followed up in April with a three-minute video showing a nine-year-old male macaque named Pager, with chips in either side of its brain, playing a game of Pong, the famous 1970s video game that mimics a game of table tennis. Initially trained to play the game with a joystick, and rewarded with a banana smoothie sip for each correct move (fed through the metal straw above) he appears to be playing the game by simply thinking. According to the video, Neuralink records

and decodes electrical signals (below) using more than 2,000 electrodes implanted in regions of the monkey’s motor cortex that coordinate hand and arm movements. The experiment is one of Neuralink’s first steps towards developing wireless brain computer chips that can help circumvent neurological conditions like Alzheimer’s, dementia, and spinal cord injuries. Potential applications include enabling someone with paralysis to use a smartphone with their mind, according to a tweet from Musk.

the visual canvas of the brain. But there’s a problem: to read a complex percept like a tank moving at speed, you need to measure the dynamic firing of many individual neurons over a short time span. To do that, Robinson needed much higher resolution than the MRI could offer. The team turned its sights to something called a GEVI, or genetically encoded voltage indicator. These are fluorescent proteins that, when inside a neuron, detect the electrical changes that happen when it fires. The proteins respond by changing colour. Get GEVIs into a bunch of cells in the visual cortex and you could find out which ones were firing and what the soldier was seeing, with resolution at the level of individual neurons. But how, precisely, would you get a GEVI into a soldier’s brain cell? In mice it’s possible to attach the GEVI genes to a virus – a relative of the adenovirus that causes the common cold – which infects the cell and co-opts its machinery to make the GEVIs. But you don’t want a scattergun result; you want your GEVIs confined to the visual cortex. The solution is to inject your genetic payload into the blood with a stream of tiny air bubbles. Then you direct a beam of ultrasound onto the bubbles and something special happens. “When that focused ultrasound interacts with the microbubbles, the bubbles cavitate and that opens up the blood brain barrier. So those viruses that are in the blood can then escape the blood brain barrier only in that specific spot,” says Robinson. The process, called sonoporation, offloads the genetic cargo in tightly cordoned regions of the brain’s geography. So, let’s say your soldier sees a tank and a tank-shaped formation of neurons trips the GEVI switch and changes colour. How are you going to detect it? The principle is that the fluorescing cells will absorb more light of a given wavelength than their surrounding buddies. Shine a light on them and measure how much bounces back and your active neurons will look darker than the ones adjacent. The technique is called diffuse optical tomography, or DOT – think of it as a CT scan that uses light instead of X-rays. Robinson’s team is refining a high-spec skullcap to shoot out and detect the reflected light. To see whether it works they’ve also made a “skull phantom”. It’s a mouse-sized, 3D-printed resin cover put over the rodent’s brain to mimic the light-scattering properties of the human cranium. Using a technique closely modelled on all of the above, they had a mouse look at two computer monitors displaying black and blue chequerboard patterns, one on the right and one on the left. The brain is wired to relay those patterns to the opposite side of the mouse’s visual cortex. “The space between those two spots in the visual cortex is a couple of millimetres. So the question cosmosmagazine.com 57

Vulcan mind meld to cure blindness is welcome, but the potential for misuse is also real. is, could we tell by reading the brain activity if the mouse was looking at something on the left side or the right side?” says Robinson. “We were able to do that classification.” The experiment is unpublished, but it is proof of principle for the “read” side of Robinson’s brainto-brain interface. Do the same thing with a soldier – label brain cells with colour changing GEVIs that you detect with a light-scanning helmet – and the hope is you’d pick up the tank in their visual centre. But how would you write it to another brain? Robinson’s team wants to use the same, ultrasound-targeted virus 58 COSMOS MAGAZINE

technology to deliver a genetic payload to a mirror image bit of brain in the recipient. This time, however, the genes have a new mission. They create ion channels in the brain cell, the ones through which calcium flows to trigger the firing of the neuron. These new channels come with a special capability: they are sensitive to temperature, which is critical for what happens next. Tiny particles of iron are injected and sent to the same region, using ultrasound targeting. Apply a weak magnetic field to the area – think a TMS doughnut with the voltage turned down – and the iron heats up, the calcium channels open, the neurons fire and, voila, you’ve written your tank onto a new brain. It is called magnetogenetics and, no, this hasn’t been done in people yet either. “We’ve tested this idea of magnetic stimulation in fruit flies. We’ve been able to show that we can drive the activity of genetically targeted neurons with a magnetic field,” says Robinson. In short, by writing to the fruit fly’s brain, Robinson made them do their mating dance in a Petri dish, at the flick of a magnetic switch. All of which may seem a long way from application in humans. And who, after all, would put their hand up

MARK STONE / UNIVERSITY OF WASHINGTON

The prospect of a

NEUROENGINEERING

The end play of the telepathy cap (opposite) is to be able “read” from one brain and “write” directly into another. Researchers (above) have achieved a version of this with fruit flies (left), utilising iron

JACOB ROBINSON X2

nano-particles and a weak magnetic field.

to have an experimental genetic therapy? The payoff would have to justify the risks and also satisfy the US Food and Drug Administration, the body that approves medical devices. Robinson thinks the disability that comes with blindness makes it a realistic target for their device, which they call MOANA for “magnetic, optical and acoustic neural access device”. Hitting the ground running, he’s aiming at human trials within two years – in the first instance, the team hopes to fit a blind person with a head-mounted camera, then “write” what the camera sees to their visual cortex. There is, however, a fundamental challenge for the entire MOANA project. Let’s say I see a tank and it ignites a pattern of neurons firing in my visual cortex. How do I know that recreating the same pattern in your visual cortex will make you see a tank? Maybe you’ll see a truck, or just a rectangle, or perhaps nothing at all? The receivers in Rao’s Tetris study mostly saw a phosphene when their brain was zapped, but if they were thinking about other things it could disappear, or never appear in the first place. Rao is developing a “brain co-processor” to address the issue of brain states getting lost in translation. It uses AI and deep learning to calibrate a computer to know what pattern of brain activity means “tank” for you. It’s a painstaking, bespoke process of stimulating neurons until you yell out “yep,

I’m seeing a tank now”. The computer learns with the same carrot-and-stick method we use to train our pets, our children and ourselves. “Think of it as reinforcement learning,” says Rao. “The reinforcement is the reward signal the algorithm gets. It’s like a little boost saying ‘hey, you did well, you succeeded’. Whereas if the co-processor was trying to stimulate and get the person to see a truck and they saw a face, then you have a big error signal. You can also use this error signal to drive the co-processor’s learning saying, ‘oh, you did badly’.” The prospect of a Vulcan mind meld to cure blindness is welcome, but the potential for misuse is also real. It’s something Walter Glannon, a neuroethicist at the University of Calgary in Canada, deals with in his forthcoming book Neural Prosthetics: Neuroscientific and Philosophical Aspects of Changing the Brain. “There could be manipulation of the brain and certain mental states that would coerce people into performing actions they didn’t want to perform,” says Glannon. Bad actors could “brainjack” into the device to trigger compulsive behaviours like hypersexuality or problem gambling – we already see these as “off target” effects of deep brain stimulation, where implanted wires deliver electric pulses for conditions such as Parkinson’s disease. It’s worth noting, though, that neither Rao’s program nor N3 currently target these deeper structures. Glannon notes criminal behaviour has been associated with reduced activity in the prefrontal cortex, the seat of our self-control. If the device detected a person’s tendency to the antisocial, that could pose challenges for the emerging concept of mental privacy, and what it protects. “Insurers and employers could take that information and draw whatever inferences they want to about it,” says Glannon. Robinson and Rao both make clear they are sensitive to ethical concerns – Robinson is developing an ethics framework with the Institute of Electrical and Electronics Engineers and Rao has a neuroethics team embedded at his centre. But the endgame is firmly etched on the research horizon. For Rao it is to harness the hive mind of humanity in a seamless BrainNet, a biological Powerwall with scope for endless expansion by simply adding another brain. Maybe all those brains could cure cancer or get people on Mars – or maybe even tell us who we are. “The brain is kind of this final frontier in terms of understanding the human condition,” says Rao. It is a sentiment imbued with a deep humanism, expressed in language that any self-respecting Trekkie will surely recognise.

PAUL BIEGLER is a bio-ethicist based in Melbourne. His last story for the magazine, on embryoids, appeared in Issue 86. cosmosmagazine.com 59

Forces of nature

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GALLERY

Sedge wren splits (above): A sedge wren (Cistothorus stellaris) shows off its dexterity, balancing between two stems of grass in the Falkland Islands in the remote South Atlantic. This wren is the islands’ smallest bird species and one of two wrens. Unlike the Cobb’s wren, which is only found in the Falklands, subspecies of the sedge wren can be found throughout the Americas – but it is often elusive as it flits through its grassland habitat. Photographer: Andy Pollard Award: Silver in Behaviour – Birds Into the blue (left): Early one summer morning, Andre Fajardo freedives below the Hawaiian waves. He’s surrounded by a bait ball, which forms when small fish swarm into a spherical formation, commonly to defend from predators. Photographer: Christa Funk Award: Gold in People and Nature

The World Nature Photography Awards are built on a simple philosophy: “Whilst we know that the challenges around climate change are enormous, amazing things can be achieved if we all come together to effect change.” This year’s winning images celebrate the call of the wild. Deadline for entries to the 2021 World Nature Photography Awards is June 30, at www.worldnaturephotographyawards.com/enter cosmosmagazine.com 61

Glacial veins (above): This otherworldly image captures a glacial river as it flows down through black sands of the south coast of Iceland to the Atlantic. Glaciers blanket approximately 11% of Iceland’s land area, with the largest located in the southern and central highlands – but as the world warms and glaciers melt into rivers, the country’s landscape is being dramatically reshaped. Photographer: Dipanjan Pal Award: Gold in Nature Art

The real joker (left): This toothy grin belongs to a parrotfish, a family of charismatic characters found in tropical reefs around the world. These fish use their teeth – 1000, lined up in 15 rows in a beak structure – to crunch up coral, eating not only the calcium carbonate skeleton but also soft-bodied polyps, algae and bacteria. Parrotfish absorb the tissue and excrete sand – up to 450 kilograms per year. In the Maldives, where this image was snapped, the tides are too gentle to grind down coral debris; scientists think parrotfish are the architects of the islands’ beaches. Photographer: Pavlos Evangelidis Award: Bronze in Nature Art 62 COSMOS MAGAZINE

GALLERY

The world upside down (above): The Bornean orangutan (Pongo pygmaeus) is an ape in crisis: over the last 60 years, the massive expansion of palm oil plantations has destroyed more than half of its rainforest habitat, sending populations plummeting. This intelligent species is now critically endangered, with just 100,000 individuals left in the wild. Since orangutans spend 95% of their lives in trees, capturing this image was a feat of patience: the photographer climbed a tree that grew in a watery area and lay in wait for hours for the perfect moment, knowing that he was on a path that orangutans regularly followed to cross to another island. His perseverance paid off. Photographer: Thomas Vijaya Award: Gold in Animals in Their Habitat; Grand Prize of World Nature Photographer of the Year cosmosmagazine.com 63

An interloper approaches (above): On the Serengeti plains, an intruder dares to approach a water hole already claimed by a small pride of lions (Panthera leo) – and is attacked. The battle ends with the interloper successfully chased away. Home to over 3000 lions, the Serengeti in northern Tanzania is thought to have the largest population in Africa, likely because of the abundance of prey – including 1.5 million wildebeest, which every year undertake the world’s largest remaining unaltered migration. Photographer: Patrick Nowotny

Award: Gold in Behaviour – Mammals

Mist over the swamp (left): Misty dawn over a lake in east Texas in early autumn. Rising from the water are bald cypress trees (Taxodium distichum): long-lived, slow-growing trees with water-resistant wood. A common sight in southwestern USA, thousands thrive in swamps, lakes and bayous. The trees are deciduous, but in warm climates the leaves can persist year-round. Here, the fall foliage lights up the water below. Photographer: Doron Talmi Award: Gold in Plants and Fungi

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GALLERY

No horn, no problem (above): In the Thanda Safari Game Reserve in South Africa, dehorning white rhinos (Ceratotherium simum) is considered a necessary evil. After a rhino is immobilised with a powerful cocktail of drugs, the horn – made primarily of keratin – is sliced off above the living growth plate at the base, in order to make the rhino less valuable and thus save its life. Ten years ago, more than 1000 rhinos were killed each year in South Africa by poachers, seeking to sell horns for everything from traditional medicine to status symbols. By 2019 this number had dropped to 594. Photographer: Gunther de Bruyne

Award: Gold in Nature Photojournalism

We’re gonna need a bigger boat (below): A northern giant petrel (Macronectes halli) floats above the Ningaloo Reef, off the coast of Western Australia. In winter and spring, these migratory birds are regular visitors to Australian waters, with their range extending as far north as the subtropics, but they breed in the chillier southern latitudes on subantarctic islands and South Georgia. Their wingspan is huge, reaching over two metres – here, a trick of perspective makes this petrel look like birdzilla. Photographer: Naomi Rose Award: Silver in People and Nature

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GA

GAIA’s plots of the 14,099 asteroids orbiting between the Sun and Jupiter show the Sun at the centre, Earth as the inner white circle and Jupiter as the outer white circle. Orbits coloured by albedo (above) – the “lightness” of an asteroid’s surface –show dark asteroids (red) dominating the external regions, with the lightest bodies in the inner Main Belt. Orbits coloured by perihelion distance (right) – the minimum distance from the Sun – show the trajectories of Near-Earth in blue and those of Main Belt asteroids in green. Jupiter’s gravitational perturbations are evident, except for Trojan asteroids (red) that precede and follow the planet in safe, stable regions. Coloured for their eccentricity (opposite), most asteroids’ orbits are nearly circular (green), while others take eccentric paths that zip close to the Sun (purple).

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ASTRO

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The European Space Agency’s peerless space telescope continues to break new ground in astrometry, and the best is likely yet to come. ESA / GAIA / DPAC, P TANGA X3

Richard A. Lovett reports.

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ust over four centuries ago, the Dutch mathematician Willebrord Snellius measured the approximately 116 kilometres from Alkmaar, in North Holland, to Breda, in the country’s south, by breaking it up into quadrangles built upon a chain of 33 carefully constructed triangles. Snellius – better known in the English-speaking world as Snell (as in Snell’s law, of light refraction) – underestimated the distance by 3.5%. Still, it wasn’t a bad first effort in modern times to use triangulation as a survey method, especially because the quadrant he used (an instrument for measuring angles), although revolutionary for its time, was only accurate to tenths of a degree. People improved on Snellius’s work (largely by developing ever better methods of measuring angles) throughout the 18th and 19th centuries, eventually reaching a point of accuracy that was surpassed only when global navigation positioning systems became commonly used from the 1980s. cosmosmagazine.com 67

Eyes in the sky Astronomy is best known for the spectacular images produced by the best telescopes. But it is a field with many subdisciplines, one of the earliest of which is astrometry. Stripped to its basics, astrometry is nothing more than the making of sky maps. Google Earth for the heavens: a tabulation of the positions, brightnesses, and colours of the stars. Modern astrometers have also included distances and motions, but the idea goes back to the ancient Greeks, who by the time of Hipparchus (~190 BCE to ~120 BCE) had created a catalogue of nearly 1,000 stars. “It’s one of the oldest sciences, ever,” says Leanne Guy, data management project scientist for the US’s Vera C. Rubin Observatory. Such maps are, of course, incredibly important to backyard stargazers trying to figure out where to point their telescopes. But to the ancients they served 68 COSMOS MAGAZINE

Gaia Sky (above) utilises the data from Gaia (right) to create an open-source simulation of our local stellar neighbourhood, complete with planets, dwarf planets, some satellites, moons, asteroids, trajectories, locations and more. It’s used for both scientific and recreational purposes; anyone can download the map and data sets – including star clusters, nearby galaxies (NBG) or distant galaxies and quasars (SDSS) – and cruise round their favourite part of the Solar System and beyond.

more practical purposes, such as allowing sailors to navigate the ocean or farmers to track the seasons so they knew when to plant crops. Today, GPS has replaced stars for navigation and astrometry has far outstripped the needs of people wanting to know where to point a telescope. “The data is about 100,000 times more accurate than we need,” says Oregon-based Jerry Oltion, an amateur astronomer, telescope-maker and columnist for Sky & Telescope magazine. But that doesn’t mean astrometry is a relic of history.

ABOVE: ESA / GAIA

But GPS only works on Earth. If you want to look at and map objects much further out in space you need another method. European space telescope Gaia does this by going back to the future: it uses a process akin to how surveyors measure distances on Earth, but on a far grander scale. “[Gaia] uses the Earth’s orbit to provide a long baseline to triangulate [on stars and] relies on making very accurate measurements of positions,” says Nick Rowell, a wide-field astronomer at the Royal Observatory of Edinburgh, Scotland. And Gaia isn’t just doing this for a few stars. Its latest data release, announced last December at a press briefing by the Royal Astronomical Society, now maps the positions, brightnesses, distances and motions of 1.8 billion stars. The whole process is a testament to the advancement of computer technology, not just while Gaia was being built, but afterwards. “They are absolutely dependent on Moore’s Law,” says George ‘Fritz’ Benedict, a retired astrometer from the University of Texas, Austin (citing the famous computer-tech dictum that processing capabilities double every two years). “When they built this, the computers absolutely weren’t fast enough to process the data. Now they can.” Even though it is still collecting data, Gaia is already making its mark on astronomy: as of April 2021, the Astrophysics Data System at Harvard University listed a whopping 5172 refereed Gaiarelated studies. “There is hardly a field of astronomy that isn’t revolutionised by Gaia,” says Dafydd Evans, a Gaia researcher at the University of Cambridge, UK. Martin Barstow of the University of Leicester, UK, calls it “a tsunami rolling through astrophysics. You’ll be talking about astronomy before Gaia and after Gaia.”

TOP: GAIA SKY. RIGHT: ESA / GAIA. NEXT SPREAD: ESA / GAIA / M FOUESNEAU / R ANDRAE / CAL BAILER-JONES / O CREEVEY

GAIA

At the heart of this is Gaia, launched in 2013. It’s the successor to a prior ESA space telescope called Hipparcos, which orbited the Earth from 1989 to 1993. Hipparcos wasn’t large as telescopes go – only 29 centimetres in diameter – but in space, free of the distorting effects of the Earth’s atmosphere, it was able to collect the most accurate information then available on 118,000 stars, measuring their positions to an accuracy akin to spotting a $1 coin at a distance of 2,500 kilometres. Gaia took that groundbreaking effort and raised it exponentially. Hipparcos was “pretty good,” says Benedict. “Gaia is about 50 times better.” Gaia does its magic via a pair of rectangular telescopes each measuring 145 x 50 cm, substantially larger than the one on Hipparcos. Rather than being in Earth orbit, it is in a location called the L2 point, about 1.5 million km from Earth (see box at right). There, the balance of forces from the Earth and the Sun keeps it on station, while also holding it in an orbit where Earth never blocks its view. (NASA’s upcoming James Webb Space Telescope, scheduled for launch on 31 October this year, will also be placed at L2.) Gaia’s twin mirrors focus starlight onto a onebillion-pixel camera, the largest such detector ever launched into space. It’s so good that Gaia can do the

GAIA’S SPIN CYCLE Gaia travels in a controlled orbit around the L2 Lagrange point – one of five positions where the competing gravitational pull of Earth and the Sun hold a satellite relatively stable. Gaia spins at a constant 60 arcseconds/second; each five years in space it will scan each object in view around 70 times.

EARTH

at L2

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Just as atmospheric dust colours sunsets on Earth, interstellar dust affects the light we see from stars and galaxies. It preferentially scatters shorter wavelengths and leaves behind longer wavelengths, making stars appear dimmer and redder than they actually are. This 2D projection is a dust map of the whole sky, centred on the heart of the Milky Way. It was created using data from 88 million individual stars spied by Gaia, allowing astronomers to quantify the average “interstellar extinction” caused by dust – and therefore account for it in their measurements of stars and galaxies. AG refers to the magnitude of extinction along the line-of-sight: the brighter the colour, the more strongly light is attenuated by dust. The map reveals many of the Milky Way’s features, such as the disk of the galaxy and the fine structures of large dust clouds. 70 COSMOS MAGAZINE

GAIA

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Greedy galaxies Closer to home, Gaia is helping to reveal how our own galaxy has grown through mergers with smaller ones. “The Sagittarius dwarf galaxy (65,000 light years away) has moved through the Milky Way on at least three occasions,” says Guy. Models show that these have been occurring with increasing frequency as the Sagittarius dwarf galaxy moves toward eventual merger with the Milky Way. The first collision was 5–6 billion years ago. The next was two billion years ago. The most recent was one billion years ago. That much had been previously known. But Gaia data suggest that the first of these collisions might have been responsible for the birth of the Sun. That’s possible, because such collisions can disturb gas and dust clouds, which in turn can trigger bursts of star formation. Gaia can detect the timing of such bursts because, along with measuring the positions, 72 COSMOS MAGAZINE

SEEING THE UNSEEN Stars aren’t the only things Gaia can detect. It can also help find dark matter, a mysterious substance that appears to make up the bulk of the Universe. “We have no idea what dark matter is,” says Gerry Gilmore, of the University of Cambridge, UK. But even if it’s invisible, Gaia can help determine where it is by measuring the effect of its gravity on things we can see. One of these is the Sun. Astronomers have long known that the Sun (and the Earth) orbit the galactic centre once every 230 million years, moving at a velocity of about 230 kilometres per second. But we’re not going in a straight line. Rather, the galaxy’s gravity is bending

our movement, keeping us from wandering off into the intergalactic void. And now, Gaia has allowed us measure that rate of deflection to astonishing precision. The number? About 7.3 km/second/million years, Gilmore and others reported recently in Astronomy and Astrophysics. That sounds like a lot, but a million years is a long time. Reduced to human timescales it means the Sun’s motion around the galaxy is being bent by gravity by a whopping 7.3 mm/year. That’s about the rate at which tectonic plates move here on Earth. But it’s more than can be accounted for based on visible matter alone. “The immediate conclusion,” Gilmore says,

“is that roughly half the weight interior to the Sun is dark matter.” Other researchers are using Gaia data to try to find out whether dark matter is broadly dispersed or exists in clumps. In a 2019 paper in The Astrophysical Journal, a team led by Ana Bonaca, of the Harvard-Smithsonian Center for Astrophysics, took a detailed look at a star stream called GD-1, far out in the Milky Way’s halo. What they found was odd. “We see stars pulled out of this stream,” Bonaca says. Best guess? Half a billion years ago, a ball of dark matter with a mass of about five million Suns ploughed through it, scattering stars like confetti in its gravitational wake.

ESA / GAIA / DPAC / UB / IEEC

equivalent of spotting a $1 coin on the Moon – an accuracy only expected to improve as Gaia continues to collect data. The ultimate goal, says Giorgia Busso, an astrophysicist at the University of Cambridge, UK, is to be able to do the equivalent of reading the title of a book on the Moon. And that’s just the tip of the Gaia iceberg. Gaia can also measure the motions of these stars. Some of these are radial motions – the stars’ movements toward or away from us. These are measured by looking for Doppler shifts in key spectral lines. If they are shifted to the blue, the star is moving toward us. If they are shifted to the red, it’s receding. Trickier are the stars’ “proper motions” – their sideways movements across the sky – but Gaia’s hyper-precise mapping ability allows these to be measured by tracking position changes over time. Put the two together with the star’s distance and you have the star’s motion in three dimensions. To get the distance, Gaia measures how the star’s apparent motion oscillates as viewed first from one side of the Earth’s orbit, 150 million km to one side of the Sun and then, six months later, 150 million km to the Sun’s opposite side, allowing astronomers to accurately triangulate stars tens of thousands of light years away. In a dramatic demonstration of the power of Gaia’s data, Busso and colleagues plotted the positions, distances, colours, and motions of 303,446 stars within 100 parsecs (326 light years) of the Earth. Prior to Gaia, she said, there was only enough data to do that for slightly less than 6000 stars. Now, in one giant leap, it’s expanded by a factor of more than fifty. “[Gaia] is going to improve the verisimilitude of all kinds of space shoot-em-up games!” Benedict laughs. And that’s just one trick you can do with that data. It’s possible to project the positions of these stars millions of years into the future, or backwards to see how stars presently far apart might once have been more closely associated.

GAIA

HIGH AND MIGHTY Gaia packs an impressive amount into its 3.5-metre-wide frame.

ABOVE: ESA / GAIA / DPAC, S JORDAN, T SAGRISTA X2. RIGHT: ESA / ATG MEDIALAB

Payload module houses Gaia’s two telescopes – whose 5 mirrors each include a primary mirror with a collecting area of about 0.7m2 and its three instruments: • the astrometric instrument measures stellar positions • the radial velocity spectrometer calculates stars’ velocity by measuring the Doppler shift • the photometric instrument provides colour information by generating two spectra, one in the blue and one in the red range of the optical spectrum

distances and motions of stars, it also measures their brightnesses and colours – measurements astro­ physicists can use to calculate their ages. In a 2020 paper in Nature Astronomy, a team led by Tomás Ruiz­Lara, an astronomer in the Instituto de Astrofísica de Canarias, Spain, did just this for millions of stars within 2,000 parsecs (6400 light­ years) of the Earth, finding three major bursts of star formation coinciding with the three collisions, peaking 5.7, 1.9, and 1.0 billion years ago. Did that collision create the Sun and, by exten­ sion, us? Who knows? The Sun came on the scene 4.6 billion years ago, close enough to the peak of the first Sagittarius stellar baby boom to be intriguing. Other collisions are more ancient, such as the one that created a group of stars known as the Gaia Sausage. These are remnants of a fairly large dwarf galaxy that ploughed into the Milky Way about 10 billion years ago and was shredded in the process. “While there have been many dwarf satellites fall­ ing onto the Milky Way over its life, this was the largest of them all,” says Sergey Koposov, physicist at Carn­ egie Mellon University, Pittsburgh, Pennsylvania, and co­author of a 2018 paper about the collision in Monthly Notices of the Royal Astronomical Society. When Gaia data were used to plot the orbits of these stars, something that stood out was how

10-m-diameter deployable sunshield keeps Gaia in shadow, maintaining the payload module at an almost constant –110°C

Thermal tent protects the payload module’s instruments

Service module contains electronic units to run the instruments, the propulsion system, communications units and other components Propulsion systems High gain antenna

Deployable solar panels

Fixed solar panels

In a test run before official mission start, Gaia scanned the Cat’s Eye Nebula (opposite top; image by the Hubble Telescope) over four weeks. Its data trace the central star’s gaseous filaments; leading scientists to believe it’s actually a binary star. Gaia has since also revealed the Hyades star cluster (above left) is being disrupted by a massive unseen structure. Stars (in pink) extend out from the cluster’s heart in two “tidal tails”. If this continues, Hyades will slowly merge with the background stars of the Milky Way (green).

elongated they were, says Koposov’s coauthor, Wyn Evans of the University of Cambridge. “We plotted the velocities of the stars, and the sausage shape just jumped out at us. As the smaller galaxy broke up, its stars were thrown onto very radial orbits. These ‘sausage stars’ are what’s left of the last major merger of the Milky Way.” Other researchers are peering farther back into the galaxy’s history, looking for relics of older colli­ sions. One of these is Timothy Beers, of the University of Notre Dame, South Bend, Indiana. “My stars can be all over the sky, but I can tell whether they were once part of a dwarf galaxy or globular cluster that got destroyed,” he says. Beers has spent much of his career painstakingly searching such groups out, based on what can be deter­ mined from ground­based telescopes. “I’ve done that for tens of thousands of stars, looking for clustering in orbits,” he says. cosmosmagazine.com 73

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ESA / GAIA / DPAC

The stars are in constant motion. To the human eye this movement, known as proper motion, is imperceptible – but Gaia is measuring it with more and more precision. The trails on this image show how 40,000 stars, all located within 100 parsecs (326 light-years) of the Solar System, will move across the sky in the next 400,000 years.

GAIA

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By the time it completes its final catalogue (possibly in 2025), Gaia will have cost the European Space Agency nearly €740 million (about $1.145 billion) to build, launch and operate, plus another €250 million ($387 million) to convert its raw data into usable form. But once that processing is completed for each batch of data, ESA will make it open access – instantly

The US’s Vera C Rubin Observatory (top), in Chile, will be fitted with a 3.2 gigapixel camera (lens, above centre); it’s due to start snapping shots from late 2022. The tests – of a Romanesco broccoli, above left, and of a 1948 snap of Vera Rubin at work, above right – would need 378 4K ultra-high-definition TV screens to display at full size and resolution. The James Webb telescope (left) is scheduled for launch in October to the same location as Gaia. Its 25m2 primary mirror will search for the first galaxies formed after the Big Bang.

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available to every scientist in the world. “This was not an easy choice,” says Jos de Bruijne, an ESA support scientist for Gaia. But it was a lesson learned from Hipparcos. There, the data was held proprietary for one year and doled out to researchers whose proposals were accepted. Doing this, he says, turned out to be a “non-negligible” task, fraught with all kinds of internal politics. “Not having proprietary data rights simplified things a lot,” he says.

Gaia makes the process vastly easier. “It’s almost like a magic trick,” Beers says. In a 2020 paper in The Astrophysical Journal, he and a team of international colleagues found 57 such groups, some associated with previously known structures, like the Gaia Sausage, but 20 never before observed. Of particular interest, he says, are ones that are low in elements astronomers call “metals”, meaning anything heavier than hydrogen and helium. These stars are the most ancient of the ancient, born early in the history of the universe, before astrophysical processes had enriched the gas clouds from which they condensed with heavier elements. “The lower the content of metals, the more ancient we figure the star is,” Beers says. Traditionally, identifying them was a slow and laborious process, involving large ground-based telescopes and spectroscopy. “I’ve published papers with a couple thousand stars it took 25 years to find,” Beers says. But again, Gaia has come to the rescue, because its colour measurements, Beers has found, can be used to create a colour index that can be

TOP: RUBIN OBSERVATORY / NSF / AURA X4. LEFT: NASA / JPL

OPEN-ACCESS DATA

GAIA

QUEST FOR QUASARS

combined with other data to produce a “reasonably accurate” estimate of the metal content of each and every star in the Gaia catalogue.

ABOVE: ESA / CALTECH / T PYLE (IPAC). TOP RIGHT: ESA / GAIA / DPAC

Grounding Gaia In Greek mythology, Gaia was the mother of all life. And while the space telescope that bears her name isn’t spawning anything other than vast quantities of data, it is indeed helping astronomers peel back the veil of history into the origins of our entire galaxy. And, as Beers discovered by correlating Gaia’s red/blue colour index to metallicities, astronomers may be just beginning to figure out all the ways in which its data can be used. “It’s like a tool that’s waiting for the right question to be asked,” says Benedict. Meanwhile, Gaia’s days for producing new data are numbered. Sometime in the next few years, it will run out of manoeuvring fuel and be unable to keep itself precisely on station. But by that time, the Vera C. Rubin Observatory, now under construction on a mountaintop in northern Chile, should be online. As a ground-based telescope, it has certain disadvantages compared to Gaia. To begin with, it can only see in certain directions. “A space telescope can see 360 degrees,” says Guy. “We will see roughly half the sky, up to 20 degrees north.” Also, even at 2682 metres in altitude, the Vera C. Rubin isn’t free of distortion from the Earth’s atmosphere, so it can’t do astrometry at Gaia’s level of precision. What it can do is use a much bigger mirror – an 8.4m primary that allows it to see stars hundreds of times fainter than those visible to Gaia. That, Guy says, will let it see 17 billion stars, a 10-fold improvement

Gaia’s second data release precisely mapped 556,869 quasars. Astronomers used this information to create a celestial reference frame: a fixed but imaginary grid against which everything else moves, comparable to Earth’s lines of longitude and latitude. Since the planet spins and wobbles, such a frame is important to not only guiding where we point telescopes but also keeping GPS systems working accurately. This image shows the formal position uncertainty of the quasar sources across the whole sky, which averages less than 0.2 milli-arcseconds. In 2018 Gaia captured an “outburst” from a FU Orionis star – a type of young, near-infant variable star that displays extreme changes in magnitude and spectral type. An illustration of an FU Orionis undergoing a growth spurt (above left) shows material from the star’s debris disk (orange) and hot gas (green) flowing into the star. As more material enters, the inner disk heats up and the star bursts, with gas (yellow) flowing outwards. Astronomers think these outbursts are how these young stars acquire their mass.

over Gaia, and about one-sixth of all the stars in the Milky Way. (It will also be able to see an estimated 20 billion distant galaxies, though those are much too far away to measure their distances by triangulation.) And unlike Gaia, which only looked at any given star twice a year, it will be able to scan the visible parts of the southern sky every few days, allowing astronomers to look for much more subtle stellar movements. “Over the course of 10 years, every [star] position will be observed roughly 825 times,” Guy says. That will allow it to detect not only the motions of stars, but to spot asteroids, Kuiper Belt objects, and interstellar interlopers such as the object known as Oumuamua, which zipped through our Solar System in 2018. It might even find the mysterious Planet 9, thought to lie at the far fringes of our Solar System. All of which means that astrometry continues to be on a roll. “It’s better than a golden age,” Benedict says. “It’s a platinum age.”

RICHARD A. LOVETT is a science and science fiction writer based in Portland, US. His most recent story, about lithium, appeared in the last issue. cosmosmagazine.com 77

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BERNARD FRIEL / GETTY IMAGES

A scientist’s guide to dating

How do we know how old things really are? As Rachel Williamson reports, it can be more controversial than it seems.

I

n 2018, a Dutch pensioner tried to legally change his age. Having to admit to a chronological age of 69 was torpedoing Emile Ratelband’s swipe-right rate on the dating app Tinder, and besides, his doctors claimed his “true” biological age was a sprightly 45. Ratelband decided a more accurate official age should knock at least two decades off his current count. The perky pensioner’s argument for the law to recognise biological over chronological age didn’t wash with the Netherlands court, however. It declined to let one man’s dating prospects alter the legal definition of age. But although global media chuckled at Ratelband’s chutzpah, what our lusty pensioner needed to show the court was Horvath’s Clock, a molecular diary of DNA changes published in 2013 by US geneticist Dr Steve Horvath that measures biological, or epigenetic, age. One of the foundations of the current ageing and disease predictor research, Horvath’s Clock tracks the patterns of chemical tags on DNA made by methyl molecules over time. These correlate with a person’s chronological age; life in the fast lane can speed it up – smoking will do that – while exercise and diet can slow it down. Youth-seekers need to be careful which body part they’re basing their preferred biological age on, however: breast tissue ages faster than other cells, but the heart has been found to be up to 10 years “younger” than blood and 12 years younger than a person’s chronological age. cosmosmagazine.com 79

The science of chronological dating relies on a museum-cabinet’s worth of research that seeks to find the age of everything from the Earth itself, to sharks and crustaceans, to Indigenous culture in Australia. It uses methods that range from cutting-edge technology to simple, careful counting. Ring counting is a common and longstanding age marker for many types of flora and fauna. In sharks, you can count vertebra rings; in dinosaurs, it’s bonegrowth rings; in whales, the colour of earwax layers show different seasons. While these are generally accepted measures, one of the limitations rests in not always knowing the age of a significant data set of animals from which to validate these methods. The hundreds of whale earplugs that have been studied, for example, have all been taken from dead animals whose actual age was never known. Researchers like Baylor University biologist Stephen J. Trumble have compensated for the lack of earplugs from whales with a known age by using re-sightings of individuals, hormone data to find how many times a cow has been pregnant, and even versions of Horvath’s Clock as earwax age validation. “While not perfect, ageing using the earplug, especially when we have additional data (re-sights, ovaries, etc) makes it one of the best indices thus far,” Trumble says. Sometimes, it’s the science itself that’s called into question. In 2012 researchers thought they’d cracked the mystery of how to find the age of crabs, shrimps and rock lobsters, a problem for fisheries’ managers charged with sustainably managing stocks of the popular crustaceans. A rock lobster study suggested tiny calcified rings on the eyestalks and on secondary teeth in their stomachs were markers of annual moulting, but research since has cast doubt on this finding. Perhaps the best-known counting method is dendrochronology – counting the annual growth rings in tree trunks. Species like the kauri (Agathis robusta) in New Zealand and the bristlecone pines (the oldest species of which is Pinus longaeva) in North America reveal rings that correspond to every year going back for millennia. Dendrochronology doesn’t work on every tree species worldwide – the critical factor is consistent seasonal variability; so species growing in, say, a year-round damp tropical climate won’t be so “readable”. The oldest known sequence, from consecutive rings matched to multiple generations of trees, is from oaks in Europe, which go back 12,460 years. But even dendrochronology is utilising new frontiers of technology. “Molecular dating uses the genetics of the species to see how different it is from its closest relatives,” says University of Tasmania plant biologist Dr Greg Jordan. “If you assume the amount of change is 80 COSMOS MAGAZINE

The ages of sharks can be determined by counting the rings in the vertebrae (top left), but for whales (above), it’s ear wax. Diagram A is a whale’s ear canal, B is an actual plug, while C and D are cross-sections of a plug.

somehow related to how long they’ve lived, and the difference in genetics is related to how long it’s been since those species split, then you can work out when that split happened – and you can make an estimate.” The dating of the nothofagus, or Antarctic beech, is a case in point, utilising both high-tech applications and our knowledge of scientific eruptions. It’s considered to be a “Gondwana thing”, Jordan says, but molecular dating put the species split some 50 million years after the supercontinent broke up, despite species being spread over several of Gondwana’s new continents. “That kind of research has been going on for about 20 years. People have been fighting over that,” Jordan says. In recent years, it’s become apparent that some plants are actually part of the same individual – every King’s holly (Lomatia tasmanica), for example, is a genetic clone of its parent. Scientists are looking at how a still-theoretical method of genetic analysis could be used to date plants of this kind by creating a map of genetic mistakes over time.

Counting carbon

One of the best-known methods of establishing age is by radiocarbon dating, first proposed in 1946. It measures the ratio of volatile carbon-14 to carbon-12.

FROM LEFT: SMITHSONIAN NATIONAL MUSEUM OF NATURAL HISTORY. TRUMBLE ET AL, 2013. GABRIEL BOUYS / GETTY IMAGES

Ring cycles

CHRONOLOGICAL DATING

Growth rings can reveal the 4700-year age of an ancient bristlecone pine from California (middle left) by taking a cross section (left) and seeing how each year lays down a new layer of cells. The technique is also used for dating lobsters (below left),

FROM LFET: ANTANO / WIKIMEDIA COMMONS. JOHN S LANDER / GETTY IMAGES

by examining their eyestalks.

Carbon-14 has a half-life – the amount of time it takes to reduce or decay into a new chemical element, in this case carbon-12 – of 5730 years. Living tissues, like bones, stop accumulating carbon-14 when they die, so theoretically all a scientist needs to know is how much carbon-14 and carbon-12, both of which fluctuate over time, were in the atmosphere around the time of death. Then, by measuring the variation in these numbers now, they come up with an age. Of course, it’s not nearly that simple, according to ANU archaeologist and bone-dating specialist Dr Rachel Wood. “Any sample material for radiocarbon beyond about 30,000 years gets difficult, because it’s incredibly sensitive to young contamination,” she says. “If you add 1% modern carbon to a sample that’s 50,000 years, we’re going to measure 37,000 years.” To find out how much carbon-14 and carbon-12 were in the atmosphere at any given time, radiocarbon daters need to go back to those tree rings, which also lay down an atmospheric carbon record in each ring. “Without calibration, radiocarbon wouldn’t work,” says Wood. “The tree-ring method, dendrochronology, is the reason why we can do radiocarbon. We’re still building calibration curves. It’s an absolutely enormous effort to build these…particularly when you go further back in time.”

Despite its limitations, radiocarbon dating is still a handy tool for those times when you need to figure out the age of Greenland sharks (simple: just date the carbon-14 in their eye lenses – a research breakthrough in 2016 that revealed one shark had lived for 392 years). And just this year, University of Melbourne PhD candidate Damian Finch pioneered the use of wasps nests’ radiocarbon to date a painting of a kangaroo on the ceiling of a rock shelter on the Unghango clan estate, in Balanggarra country in the north-eastern Kimberley region of WA. The painting was found to be between 17,100 and 17,500 years old – Australia’s oldest known cave painting. “Constraining the age of rock art older than approximately 6000 years (ka) has remained a largely intractable scientific problem, particularly for rock engravings and for paintings where the paint no longer contains any original organic material,” Finch wrote in Science Advances last year. So he painstakingly sorted through the particles of wasps nests underneath and on top of the paintings to find particles of charcoal from bushfires. Finch dated the charcoal, which wasps picked up in the mud they used to build their nests, to provide upper and lower age limits for the paintings. But if scientists are right, we may need to imagine a time when radiocarbon dating is impossible, says Dr Chris Turney, the head of the Chronos 14Carbon-Cycle facility at UNSW Sydney. “We’ve gone from a situation in the 1960s where we flooded the atmosphere with radioactive carbon from bonkers thermonuclear bomb testing, and suddenly now we’ve gone into reverse and we’re flooding the cosmosmagazine.com 81

atmosphere with lots of what we call dead carbon – it’s got no radioactive carbon,” he says. “The practical upshot is that effectively radiocarbon won’t be able to be used, because you’ll have a massive spike in radioactive carbon from the 1960s when we did the bomb testing, and then suddenly the atmosphere appears to age really dramatically because of our emissions.”

With new methods come different age determinations, and bare-knuckle fights in Australian age dating aren’t uncommon. A war of words erupted in 1989 when Bert Roberts, Rhys Jones and Mike Smith claimed the Arnhem Land site of Malakunanja II wasn’t 18,000–23,000 years old, but more likely to be 52,000–61,000 years old. Their team had used the then-experimental method of thermoluminescence, which measures the electrons trapped within quartz crystals of long-buried grains of sand. The method is “relative” (the same as Finch using the wasp nests), dating sand around the artefacts and fossils rather than the object itself. It set off a battle by followers of absolute dating methods such as archaeologist Sandra Bowdler. Bowdler didn’t believe that Roberts et al. had “convincingly demonstrated a clear association of dated sediments and the artefacts intended to be dated” as she was “sceptical” that the rock layers in the luminescence sample site were strongly enough associated with the artefacts. “That caused quite a controversy, because up to that point it was believed Indigenous occupation of Australia was probably something like 40,000 or 45,000 years,” says Dr Zenobia Jacobs, a South African archaeologist at the University of Wollongong who helped Roberts redate the site between 2012 and 2015. “But it became quite clear that we were bumping up against what we call the radiocarbon barrier. It was very difficult to get past about 45,000 years back then, and even now it’s only 50,000 years with radiocarbon dating because there’s just too little left to measure. And even a very tiny amount of contamination can make your sample quite a bit younger.” Thermoluminescence has been surpassed by an even more powerful version, called optically stimulated luminescence (OSL). Both luminescence methods date crystalline materials to the last time they were heated – whether by human-made fires or sunlight. The mineral grains in sediments absorb ionising radiation over time, which charges the grains in “electron traps”. Exposure to sunlight or heat releases these, removing the charges from the sample. The material is stimulated using heat (thermoluminescence) or light (optically stimulated luminescence), which causes a signal to be released, the intensity of which can provide a measure of how much radiation was absorbed after the burial of the 82 COSMOS MAGAZINE

Wanna date? A fragment of zircon (above right) from rocks at Jack Hills, near Murchison, WA (sample, opposite), revealed the Earth’s age; wasps’ nests helped date Australia’s oldest known cave painting in the Kimberley, WA (a-d, left); multi-disciplinary consideration of art and other sites near Wulk Rock (centre), in Arnhem Land, produced a more complete archaeological picture of Aboriginal occupation; the remains of Mungo Man (opposite, top), in western NSW, has tested the limits of dating science.

material – provided you know the amount of background radiation at the site. One of the most profound dating fights surrounds Mungo Man, aka Lake Mungo 3 or LM3, found in 1974 in south-western NSW. LM3’s are the oldest human remains found in Australia. The body had been interred with careful positioning and ceremony and sprinkled with red ochre; it’s among the world’s earliest known examples of sophisticated, ceremonial burial practices. (See also African burial in Digest, page 8). Initial dating relied on stratigraphic comparison with the sediments in which the cremated remains of Mungo Lady (LM1) were found in 1969 – not direct examination of samples from LM3. The result was an estimate that LM3 was 28,000 to 32,000 years old. In 1987 a new method called electron spin resonance (ESR) dating was used on bone fragments from LM3, and determined an age of 31,000 ± 7000 years. “ESR measures changes in the electron structure of the tooth enamel, which are caused by radiation, for example from small amounts of naturally occurring uranium, thorium and potassium in the sediment,” Wood says. In 1999, thermoluminescence dating of sediment from the burial site returned results indicating that the burial was older than 24,000 ± 2400 years and younger

FROM LEFT: DAMIAN FINCH. /JOHN VALLEY. BEN TWEEDIE / GETTY IMAGES

Bones of contention

CHRONOLOGICAL DATING

Who listens to the radiometry?

It is through the study of uranium and other radiometric “clocks” that age-dating science enables us to look beyond the history we can see in fossils and move into geological time. Uranium-238, for example, has a half-life of 4.468 billion years, meaning it takes that long to turn into lead. Potassium-40 takes 1.248 billion years to become argon-40, and rubidium-87 takes 47 billion years to turn into strontium-87. Measuring the ratio of the “parent” elements to their “daughter” elements helped scientists arrive at the age for the Earth: 4.54 billion years, give or take 50 million years. That number was determined by dating the oldest rock found on Earth, a zircon from Jack Hills, in WA, in 2014, which set the Earth’s minimum age at 4.3 billion years. The oldest samples of Moon rocks and asteroids have been dated between 4.4 billion and 4.5 billion years, which leads scientists to say the Solar System is about 4.57 billion years old.

The study of uranium and other

FROM LFET: JAMES ST JOHN / WIKIMEDIA COMMONS. UNIVERSITY OF MELBOURNE / JIM BOWLER

radiometric “clocks” helped than 43,300 ± 3800 years. The same year, a team led by anthropologist Alan Thorne used information from uranium-thorium (which measures the decay of uranium-234 into thorium-230), ESR and OSL dating of both remains and surrounding sediment to propose a new age of 62,000 ± 6000 years. “We don’t have any uranium in our skeletons, but when you put them in the ground, the groundwater normally has just a little bit of uranium in it and that infuses into your bones,” says Wood. “It’s often a bit younger than the age of the bones themselves, but it gives you a minimum age, and that can be combined with another method, of dating teeth, called electron spin resonance, which is a bit like OSL.” For a variety of reasons, there was widespread disagreement about Thorne’s estimate. Finally, in 2003, LM3’s discoverer – geomorphologist Jim Bowler – led a multi-disciplinary team that reviewed all the available information from different dating methods to reach a determination that LM3 is about 40,000 years old. This study also determined that LM1 was the same age, not younger as was originally believed. LM3 is among the oldestknown modern human fossils, and LM1 is thought to be the oldest known example of human cremation. The lesson to take from the changing ages of LM1 and LM3 is that new techniques and new ways of preparing materials for age dating allow researchers to hone dates and push past the old limits.

scientists arrive at the age of Earth. Age-dating methods are a moveable feast of nuclear forensics, biological investigation, pollution monitoring and, in the case of tree rings, being good at counting. The history of trying to figure out how long Aboriginal peoples have been in Australia proves how tricky it can be to put a solid date on anything, but also how much things can change when new techniques appear to shake things up. Be they an aged but living lothario in the Netherlands or a fabulously preserved skeleton in the Australian desert, almost everyone wants to know how old they really are. Jacobs says that working with Aboriginal people on sites like Madjebebe has set her thinking about the meaning of time. “The way we’re trained and the way we create our narrative is all about arrival,” she says. But, she points out, “from their perspective, they’ve always been here.”

RACHEL WILLIAMSON is a business and science journalist based in Melbourne This is her first feature for Cosmos. cosmosmagazine.com 83

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In the beginning . . . The story begins in 2010, a time when the “Out of Africa” (OOA) theory ruled –which provided the answer to the question of the origin of modern humans. A hundred thousand years ago the planet was populated by a human menagerie – all members of the hominin family. Across Europe and Asia, we knew then of Neanderthals, Peking man, Java man and others. In contrast, Africa seems to have been mostly populated only by humans. But by 30,000 years ago the hominin bush had been drastically pruned. Only modern humans existed around the globe. What happened? According to OOA, the planet was taken over by Africans who exterminated or outcompeted the other hominins in Europe and Asia. It was a theory underpinned by a marriage of genetics and anthropology – the geneticists led b Allan Wilson at the University of California at Berke ley, and the anthropologists by Chris Stringer at th British Natural History Museum (see box opposite). But in 2010 that theory was challenged by th discovery of an ancient text. Ancient texts rewrit history, like the Rosetta Stone did for Egyptian histor and the Dead Sea Scrolls for early Christianity. The first evidence came from a Croatian cave, wher three 40,000-year-old Neanderthal females delivere up their DNA. It turned out to be a little differen from ours. Any two humans today have DNA cod that differs by 0.1%, but between a Neanderthal an a modern human it’s 0.14%. Those extra difference may be small, but they can be spotted when readin through the entire three-billion-letter genome that specifies a modern human – letter by letter. Imagine reading through a modern edition of the English Bible to find archaic words that had slipped through from the King James edition, such as “anon” or “bewrayeth”. When geneticists scanned modern genomes for Neanderthal words, they found them. For all non-African 86 COSMOS MAGAZINE

A Denisovan woman’s identikit, drawn by computational biologists based on her DNA alone.

ominin h e h t , o g a s r a e y 0 By 30,00 ally ic t s a r d n e e b d a h b ush uman s h n r e d o m y l n O . d e n pru ned? exis ted. What happe

Chris Stringer (abo ve right, with Neanderthal sk ull; Neanderthal model above) was an early propon ent of the Out of Africa theory ; a new breed of scientific Columbos (right) are using DN A to find new ancestral conn ections.

FROM TOP: MAAYAN HAREL. GARETH FULLER, WILL OLIVER, SILVER SCREEN COLLECTION / GETTY IMAGES

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t’s the biggest “whodunnit” in the mystery of human evolution. Who were the Denisovans? All they left behind were a few ancient fragments of bone and teeth. Human – clearly. But not enough to match anything in the fossil record. Incredibly, some of those ancient bones provided DNA. Enough for an identikit: the perpetrator should be flat-headed with a sloping forehead and an exceptionally wide face and jaw – a bit like a Neanderthal, but different. We also know these guys bred with modern humans, because we carry their DNA, especially the indigenous populations of Oceania. Now, a group of scientists have set out to find the perpetrator. They’re reminiscent of the detective Columbo, the streetwise, rumpled, trenchcoat-clad character of the long-running TV series – deftly circling, gathering a string of incriminating evidence.

HUMAN ORIGINS HUMAN MIGRATION: OUT OF AFRICA THEORY

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ILLUSTRATION: GREG BARTON

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2500 years ago

As far as theories go, “Out of Africa” has a fairly recent origin. In 1970, “no palaeoanthropologist of whom I am aware held the view that Africa was the evolutionary home of modern humans,” says anthropologist Chris Stringer. While Louis and Mary Leakey had unearthed the iconic toolmaker Homo habilis, he stood just over a metre high with long arms and a small brain. When it came to ancestors further along the family tree, all the action appeared to be in Europe and Asia. This was the home of the tall, largebrained Neanderthals, of Java man and Peking man (varieties of Homo erectus) and Homo heidelbergensis. One of the reigning theories was “multiregional evolution” – that we moderns arose through mingling. Hominins, notoriously footloose and fancy-free, kept the genes flowing freely and eventually produced the

PACIFIC OCEAN SOUTH AMERICA

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ASIA

single melting-pot variety that is us. Chris Stringer’s PhD thesis explored that theory. Travelling around Europe in 1971, he measured Neanderthal skulls to examine whether they were the likely ancestors for stone-age modern humans. He concluded they were not, and that African fossils like Omo 1, discovered in Ethiopia in 1967, were better candidates. It was an argument Stringer would continue to build as more and more African skeletons with reliable dates were unearthed in the next decades. Stringer found a surprising comrade-in-arms in New Zealand geneticist Allan Wilson, based at the University of California, Berkeley. Wilson pioneered the use of the “molecular clock” to measure the evolutionary distance between species. For instance, by measuring changes in the blood protein albumin, he estimated chimps and humans had branched off from a

Tahiti 2500 years ago

15–12k years ago

common ancestor around five million years ago. In the 1980s, Wilson began testing a DNA clock. A new technique had made it possible to follow the variation in the code, not yet by reading it letter by letter, but a method called “restriction fragment length polymorphism”. This involves breaking the DNA in a consistent way and checking the pieces, sort of like breaking a standard chocolate bar into 60 squares. But imagine the factory mould is not perfect: some bars yield 58 unit squares and a double; others 57 units and a triple, and so on. Wilson employed that DNA fragmentation approach to a small string of DNA code that resides within the cell’s energy-producing mitochondria rather than within the secure vault of the nucleus, where the main code is kept. Mitochondrial DNA provides a particularly sensitive clock because it mutates faster than

the main code. And because it is inherited exclusively via the female egg, it traces a line of maternal descent. When Wilson compared different populations, he found Africans carried the greatest diversity in their mitochondrial DNA. All other populations carried a single subset of that diversity. The interpretation, published in a landmark paper in Nature in 1987, was that if the human race is represented as a family tree, its root was Africa. Here our species had sprouted into diverse branches over time. The rest of the world was the product of just a single twig. Wilson used the DNA clock to date the root of the African tree at 200,000 years ago. And because he had used mitochondrial DNA, all modern women could trace their maternal ancestry to an African “Eve” – the lucky woman whose offspring kept on having daughters who had daughters.

cosmosmagazine.com 87

Columbo on the genetic case Denisovans have not given us a body. But they’ve certainly delivered some enthralling leads. Guided by their ancient text, geneticists scrolled through the DNA of modern individuals searching for occasional Denisovan words. One might have thought the populations of Siberia would be the best candidates for carrying them, and they do carry tiny amounts – about 0.1%, just like other populations in Europe and Asia. But the population with the strongest traces of Denisovan DNA turned up in Oceania, a hemisphere away. The indigenous populations of New Guinea and Australia carry around 4% Denisovan DNA; some island populations, particularly the Mamanwa of the Philippines, carry up to 2%. The surprise finding suggests that at least one of the trysts between modern humans and Denisovans might well have taken place on the islands of South 88 COSMOS MAGAZINE

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Denisovan info rmation is scant – a jaw bone from Baishiya K arst Cave (top) and a pinky bone (below) an d tooth from Denisova Cave in Siberia are sign ificant finds. In contra st, Homo floresiensis (m odel, left) is based on a ne arly complete skelet on and fossils from four other individuals foun d in Liang Bua cave in Flores, Indonesia.

FROM TOP: ALAMY. BILL O’LEARY / GETTY IMAGES. THELIO PARG / WIKIMEDIA COMMONS

populations, Neanderthal makes up about 2% of their DNA text, which means that at some point in time up to one in 50 ancestors was a Neanderthal. This new text didn’t just rewrite history; it shook our understanding of what it is to be human. We weren’t entirely modern: we were streaked with ancient DNA. As modern Africans ventured into the Middle East and Europe, they interbred with Neanderthals who’d been roaming Eurasia for some 400,000 years. The descendants of these trysts went on to populate the rest of the world. By contrast, modern-day Africans carry less than 0.3% Neanderthal DNA, probably a result of the migration of Neanderthals into Africa. The rewrite didn’t stop there: 2010 turned out to be a year of wonders. In Denisova Cave, located in a verdant valley at the foot of Siberia’s Altai mountains near the border with China, another hominin female was also offering up her DNA. Researchers couldn’t be quite sure what type of hominin she was: all that was left was a raisin-sized bone found in a pile of tiny bones in an archaeologist’s sieve. Some belonged to animals, but the raisin looked like it came from a human finger: a pinky, to be precise. It proved to be a rich source of DNA. As researchers read it letter by letter, it became clear that its owner was neither a modern human, nor a Neanderthal. Who was our mystery female? In the absence of a body, the new type was dubbed Denisovan, after the cave. It was the first time a new hominin species (or subspecies – taxonomists disagree) had been identified by DNA alone. Denisova Cave soon provided more DNA, from three oversized teeth – one a wisdom tooth so large and with such splayed roots it was initially thought to be from a cave bear. Emboldened, the scientists dug into a lower section of the cave to test the very sediments. Here too they detected shreds of Denisovan DNA. (See “Dirty DNA”, right.)

HUMAN ORIGINS

East Asia (ISEA). To get to those islands – and particularly to Sahul, the ice-age continent made up of Australia and New Guinea that existed until about 10,000 years ago – they’d have had to trek across the Eurasian continent, then cross 100km stretches of open water. Surely those trekking, sailing, amorous southern Denisovans must have left some remains. Enter the scientific Columbos…

Southern jawbones and algorithms

FROM TOP: ELSEVIER. ALAMY. THELIO PARG / WIKIMEDIA COMMONS

Nine years after the discovery of the pinky bone in Denisova Cave, and 2800 km to the south in the

high Tibetan plateau, another big clue surfaced. I was all thanks to a Tibetan monk who was partial to meditating in Baishiya Karst Cave. In a moment o distraction he spied a big jawbone embedded with two giant molars, which he gave to the sixth Gung-Than living Buddha, who consulted scholars and gave the jaw to Lanzhou University in 1980; the university anthropologists had no idea how to classify it. Fast forward nearly four decades. Could the jaw be a Denisovan? The molars no longer preserved DNA, but their dentine preserved fragments o collagen, the hardy protein that comprises the framework of teeth. In 2019 it was enough for an ID: the 160,000-year-old jaw was confirmed as Denisovan. A year later sediments at the Baishiya Karst Cave yielded Denisovan DNA, confirming the cave had indeed once been a Denisovan stronghold. While palaeoanthropologist were digging in Tibet, Murray Cox, a computational biologist at Massey University in New Zealand, was digging into the DNA of modern people. Previous genetic analyses of populations in Oceania suggested the Denisovans had made their way south. But how? Herawati Sudoyo at Eijkman Institute for Molecular Biology in Jakarta had painstakingly gathered samples from populations

– High tech and old school chromosome maps (right) can show the Neanderthal

and Denisovan ancestry coded into our genes; teeth comparison (below, , from left Homo luzonensis Homo erectus and Homo sapiens; tooth from Denisova Cave (bottom).

ranging from tiny islands to the remote highlands of PNG. Cox used these to drill down into the DNA codes of populations from the ISEA. Cox’s deep dive into this DNA detected relics of two different Denisovan populations. He could also estimate the dates for when these populations had interbred with people in ISEA. The calculation relies on the fact that Denisovan text, like all DNA, gets broken and shuffled as the generations progress. The longer the length of unbroken text, the more recent the interbreeding event. A genome from a recent interbreeding might still preserve an entire phrase such as “The Lord is nigh unto them that are of a broken heart; and saveth such as be of a contrite spirit.” But a recent acquisition will likely be shuffled between modern and old versions so that it reads: “The Lord will mend a broken heart; and saveth such as be of a contrite spirit”. While anthropologists have traditionally told the human origins story based on bones and stone tools, today’s population geneticists are adding chapters based on fossil DNA. Cox’s narrative suggests that some of the Siberian Denisovans formed an offshoot group that travelled to east Asia and became geographically isolated around 363,000 years ago. Over time their DNA – like their language – would have become parochial. That new parochial signature eventually became incorporated into the DNA of modern Chinese people. Another offshoot group then travelled from east Asia to Sahul, a journey involving multiple island crossings, that was not readily reversed. The offshoot group’s isolation here at around 283,000 years ago led to another new and unique parochial signature. Snippets of that signature appear to have made their way into the DNA of modern Papuans and Aboriginal Australians after they arrived between 65,000 to 50,000 years ago. The most striking finding of Cox’s cosmosmagazine.com 89

HUMAN MIGRATION: NEW IDEAS

Closing in on the suspects The scientific Columbos began circling. If Denisovans had been in Oceania so recently, surely their fossils must still be around. Perhaps they’d already been found and, like the Tibetan jaw, were lying on some university shelf waiting for the correct ID? So who were the mystery woman’s southern relatives, and where were they to be found? Since 2004, the fossil record has given us two candidates who seem to have been in the right place at roughly the right time – bearing in mind there are wide error margins on the dates. Problem is, they’re seriously weird. Homo floresiensis lived on the island of Flores (East Nusa Tenggara), in modern-day Indonesia, as recently as 60,000 years ago. The fossils found at Flores’ Liang Bua cave, which include a largely complete skeleton and skull as well as parts of 11 other individuals, show they were less than a metre tall and had a brain capacity of 426 cubic centimetres, about one-third that of a modern human. Homo luzonensis lived on the island of Luzon, in the Philippines. Fossils found here at Callao Cave include a few curved toe bones, seven teeth, two finger bones and part of a femur. They tell us that this hominid also had a height of around a metre and existed over a similar time span. Though both species walked upright, they are extremely challenging to place in the human family tree. H. floresiensis shows some traits last seen in 90 COSMOS MAGAZINE

African ancestors like H. habilis, while H. luzonensis recalls the even more primitive Australopithecines, like “Lucy”. The problem is the Denisovans were hardly dwarves – those teeth from Denisova Cave were big enough to be initially mistaken for those of a cave bear. So, how to test these suspects? None have offered up DNA; the tropics are unkind to preservation. Their ancestry appears to be super-archaic, meaning their line split from ours more than two million years ago. If the island dwarves had intermingled with the ancestors of modern people in ISEA, we should still see some traces of two-million-year old DNA in the modern populations. (The DNA of individuals can come with different date stamps, especially if there’s been interbreeding between very divergent populations.) That’s a proposition that next-gen Denisovan detective João Teixeira could put to the test. The University of Adelaide statistical geneticist teamed up with geneticist Cox and Guy Jacobs at the University of Cambridge in the UK, as well as with two heavyweights from the field: Chris Stringer at London’s Natural History Museum and Kris Helgen at the Australian Museum.

ELSEVIER X3

study was that this interbreeding event between Denisovans and the ancestors of Papuans and Australians occurred only 30,000 years ago.

ves. r a w d y l d r a h e r e w Denisovan s ve a C a v o is n e D m o r f h The teet n for e k a t is m y l l ia it in were r. those of a cave bea

HUMAN ORIGINS Denisovans left a signature of their DNA in the genomes of modern people. Not just one signature – Murray Cox’s group found three. D0 (grey) is the signature of the Altai Denisovan as found in fossils in Denisova cave in the Altai mountains of Siberia. Cox also found two variations: D1 (red) and D2 (magenta). Modern populations carry a mix of these. Modern Siberians carry only D0, or a mix of D0 and D2. Modern Europeans carry none. Modern East Asians carry only D2, or a mixture of D2 and D0. Papuans carry D2 as well as a unique signature, D1. This unique D1 signature is a clue that a population of Denisovans became isolated in Papua. When the ancestors of modern Papuans arrived they encountered that relict Denisovan population and interbred as recently as 30,000 years ago. Using this genetic information, Cox and team built a model of a family tree of hominid species, showing how populations split off and then interbred again over time with different branches. It includes four Neanderthal mixing events and two different Denisovan signatures with percentage of DNA found. Estimated population numbers are shown for each branch (Ne and in white and black); “GA” and yellow numbers denote “generations ago”.

While earlier searches relied on looking for matches to known Denisovan “words” in modern genomes, Teixeira was able to pick out super-archaic stretches unaided, using an algorithm known as Hidden Markov Method archaic. In our Bible study analogy, this is like searching the modern edition for words from long before the time of King James, say from a proto-Indo-European language. Teixeira and team trained an AI to “read” along the DNA code looking for two-million-year-old DNA. The AI read the DNA of 200 people from ISEA as well as 200 more genomes representing populations from around the world. This needle-in-a-haystack search can detect traces of super-archaic code that represent 0.1% of the DNA. “One in a thousand ancestors,” emphasises Teixeira. The verdict? Inconclusive. A faint imprint of two-million-year-old superarchaic DNA was identified, but not one strong enough to convince the authors it was introduced by a hominin down under. It may have been a “methodological artefact”. Or it may have been the residual signature from the mingling between Denisovans and a super-archaic in the northern hemisphere, possibly a Homo erectus – a finding that others have previously reported. Either way, the authors agree there is no conclusive evidence for a new super-archaic signature in people of ISEA. Anthropologist John Hawks at the University of Wisconsin, who was not involved in the study, finds it a convincing piece of work – especially since previous reports have suggested such signatures in Indian and Asian populations.

“The search for super-archaics is a rich target,” he says. “It took someone using more modern methods that are not easily tricked.” Nevertheless, the authors are not willing to let their suspects off the hook entirely. Kris Helgen can’t ignore that “evolution goes crazy on islands”. Small founding populations and extreme conditions fire up the evolutionary engine. On Flores, for instance, mainland elephants known as stegodons swam to the island and shrank. “It can happen quickly,” says Helgen. “In 100,000 years elephants can go to the size of cows or sheep.” And contrary to the oft-depicted march of humans that portrays a one-way trip to increasing modernity, “evolution can go backwards”, says Teixeira. Fruit flies, for instance, can throw up mutations that take them back to sporting four wings – a characteristic of their ancestors. So it’s not impossible that perhaps a mere 100,000 years ago Denisovans made their way to one of the islands and not only shrank like stegodons but produced throwbacks to a more ancestral state. Helgen is enthusiastic about continuing the search on other, little-explored islands of South East Asia, especially those where the megafauna survived into the modern era – a hint they had adapted to the presence of archaic hominins before modern humans arrived. Sulawesi, the largest of the stepping stones between the ice-age continents of Asia (Sunda) and Australia/PNG (Sahul), is a hot favourite. Not only does it have surviving megafauna, including the wild Babirusa pig and two species of wild buffalo called anoas, it also contains tantalising relics: stone tools cosmosmagazine.com 91

the id ea Teixeira is o pen to Homo f o m r o f d ie if d o m that a und in o f l l u sk e h t e ik l , erect us ovan. is n e D a e b t h ig m , a Jav dating back 100,000-200,000 years, and the world’s oldest cave paintings.

Just one more thing There is one more suspect, a very well-known hominin who dominates South East Asia: Homo erectus. Fossil evidence shows he left Africa about 1.9 million years ago to spread across Asia and Europe, leaving behind some beautiful pear-shaped Acheulian axes, occasional evidence of artwork, and hints that he’d tamed fire. H. erectus fossils are extremely variable – not surprising given his nearly two-million-year reign. What characterises H. erectus is the supraorbital torus – a solid bar of bone that juts like a visor above his eyes. The low forehead slopes back and he doesn’t have much of a chin. Overall, the skull is extremely thick. Some erectus had brain sizes approaching that of modern humans, particularly the population that roamed the island of Java from 1.6 million to 108,000 years ago. Around a hundred skulls have been found lodged in the banks of the Solo River – presumably victims of monsoon flooding. On one bend of the river at Ngandong, geochronologist Kira Westaway, from Macquarie University, recently dated a skull to 108,000 years that was well within the modern size range of 1100-1200cc. Could he have been Denisovan? Traditionally anthropologists would say his kind is way too distant – lying on an evolutionary branch that split from our own over 2.5 million years ago. (In contrast, Denisovans and Neanderthals split 92 COSMOS MAGAZINE

from our branch a mere 500,000-700,000 years ago.) But not everyone is as certain. The view of anthropologists Milford Wolpoff, at the University of Michigan, Alan Thorne (dec), formerly at the Australian National University, and Wu Xinzhi at the Beijing Institute of Vertebrate Paleontology and Paleoanthropology, was that H. erectus in Java and China modernised over their two-million-year stint in Asia through interbreeding with newer hominins roaming Eurasia. The modernisation of H. erectus formed a major plank of their alternate theory of human origins – not an African replacement, but more of a melting pot. Decades after that idea was buried by Out Of Africa, many folks are once again wondering whether some of those H. erectus may not have been what we thought. In China, Denisovan suspects include a 250,000-yearold H. erectus skull with some modern features found in Dali, in Shaanxi province, as well as the owner of some massive 125,000-year-old teeth found in 2015 in Xujiayao, in Hebei province. And in Denisova Cave in 2016, a small piece of skull that appeared to resemble that of a H. erectus yielded Denisovan DNA. “We might have to rethink H. erectus,” says Teixeira. He is open to the idea that a modified form of erectus, like the 108,000-year-old skull found in Java, might be a Denisovan. “It could be the Javan erectus – the problem is we have a gap of about 50,000 years between the last one at Ngandong and the arrival of moderns. I’m convinced that gap will go away.” And with all the upheavals of the last decade, even Chris Stringer, who has long argued against that theory, is keeping an open mind. “Sooner or later someone will recover proteins from a H. erectus or H. antecessor in a deep cave. They might be lucky.”

ELIZABETH FINKEL is Cosmos’s editor at large. Her last feature, on stem cells, was in Issue 86.

FROM LEFT: ALAMY. SCIENTIFIC RECONSTRUCTIONS: W.SCHNAUBELT / N.KIESER (WILDLIFE ART) FOR HESSISCHES LANDESMUSEUM DARMSTADT); KATJA LENZ / GETTY IMAGES

A comparison of H. erectus, H. floresiensis and H. sapiens (left, from left) shows greater similarity between modern humans and Homo erectus (model of female, right).

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Soap is lighter than water, so water is pulled towards the bottom of a soap bubble, pushing the soap upwards. The surface tension of water is higher than that of soap, so as the soap concentrates, the top of the sphere weakens until it’s ruptured by the internal pressure. 96 COSMOS MAGAZINE

ZEITGEIST SCIENCE MEETS LIFE

98

SCIENCE OF SOAP

We all rely on it to save us from harm, but how does it actually work?

102

FINDING FERRIS When a mathematician goes to the movies, the comedy is all in the calculations

106

GAME OF DRONES They’re fast, flashy and with fewer harmful chemicals – are they the future of fireworks?

112

PUZZLES

DON FARRALL / GETTY IMAGES

Science-inspired brain bogglers

114

PROFILE Galactic archaeologist Ioana Ciuca

cosmosmagazine.com 97

The

CHEMISTRY of

S O A P A few minor cosmetic tweaks aside, the basic recipe for soap has endured for millennia. JACINTA BOWLER looks at its literal love-hate relationship with water, its potency against a planet-busting virus, and why any attempts to improve upon it just won’t wash.

SOAP ZEITGEIST

how of hands: who has become infinitely, intimately more familiar with soap recently? If 2020 was the year we learnt to wash meticulously in between our fingers and all the way up our arms, it was also the year we discovered just how long 20 seconds in front of a bathroom mirror can be. But have you ever stopped to wonder how the humble bar of hand soap actually works? How does that slippery ‘cake’ invented thousands of years ago remain on par with hand sanitiser or any of the other modern-day cleaning products we wield against a virus that’s become a pandemic? At its most basic, hand soap is

A very similar type of molecule – called a phospholipid – is what forms our cell membranes. Those Mesopotamians invented a product we’re still using 5000 years later. Today’s soaps, admittedly augmented with exotic conditioners, oils, colours and scents, still utilise the same basic mechanism – amphiphiles. You may not know Thordarson from a bar of you-know-what, but he actually went viral in early 2020 thanks to a Twitter thread on how soap works against virus particles, so he knows a thing or two about the topic. “It was quite an experience,” he explains. “I’ve been interested in lipids ever since my pre-PhD days.” In his viral thread, which was originally a Facebook post in Icelandic, the scientist broke down the supramolecular chemistry behind soap and water’s effectiveness. Imagine you could see down to a molecular level while washing your hands. Once you rinse your hands with water and lather them up with soap, the amphiphiles get to work. The hydrophobic ends want to avoid the water at all costs, so they start to bunch up next to each

XIANGYAN MENG / GETTY IMAGES

S

just a combination of fat or oil with an alkaline substance. The first people we know of to lather up like this were the ancient Mesopotamians, who mixed animal fat with water and wood ash to produce a substance that, while no doubt greasy, smelly and hugely unpleasant, could also spirit away dirt and grime in a manner that must have appeared borderline miraculous. At its most basic, the wood ash splits the animal fat or oil (called triglycerides) into molecules called amphiphiles. These amphiphiles have one end that loves water, and another that hates it. “One end is usually bulky and shorter; we say it’s hydrophilic – it interacts strongly with water,” explains University of NSW chemistry professor Pall Thordarson. “Then there’s a longer hydrophobic end; we call it a ‘greasy tail’.”

cosmosmagazine.com 99

IN FOCUS: HOW SOAP WORKS AGAINST THE CORONAVIRUS 1. Soap molecules have a hybrid structure, with a hydrophilic head that bonds to water and a hydrophobic tail that avoids it.

H

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Tail is hydrophobic (hates water) and lipophilic (loves fat)

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Head is lipophobic and hydrophilic

An educational resource for this story is available at www.education. australiascience.tv

100 COSMOS MAGAZINE

the lipid tails on the soap molecules will try to avoid the water by sticking into the greasy virus.” Because most bacteria and viruses have cell membranes (called “envelopes” in the case of viruses), the amphiphiles can pry open the molecules like a crowbar, spilling the contents and rendering the virus or bacteria inactive. Then the amphiphiles form little spheres around the spilled contents, ready to be washed down the drain when you rinse your hands. Ignore all the different scents, colours and fancy packaging and W When water w e is splashed e into i a you’ll find that most soaps work sink, i a few w bubbles e form as air i becomes this same way. “The entire soap incorporated e with wit the water, e but because e industry is 99% marketing because they’re more or less of water’s high g surface tension e they e quickly selling the same stuff,” says disappear. e When W soap is added to the mix, the Thordarson. hydrophobic ends of the amphiphiles stick out But there’s a category of of thee water, te separating e i g thee water w e molecules e e and a soap that’s popped up in the lowering w t surface tension. This lower surfacee the last few years that claims to be “antibacterial” or “antitension means e thatt the water molecules aren’t microbial”. While this might quite as inclined to stick together, t e and seem like an advertising gimmick w when air is incorporated, i the bubbles – which it partially is – these soaps form more easilyy and stick are actually a bit different in the way they work. Some soaps marketed as

(SOAP BUBBLE) JONATHAN KNOWLES / GETTY IMAGES

other, eventually forming a sphere with the hydrophilic ends facing the water and the hydrophobic ends inside. But amphiphiles are also attracted to other non-water molecules, such as dirt, grease, bacteria, dead skin cells – even viruses. “A virus is really just a nanoscale, greasy little meat particle,” says Thordarson, “and

SOAP ZEITGEIST

2. The coronavirus has a membrane of oily lipid molecules, studded with proteins that help the virus infect cells.

Spike protein (helps enter cells) Genetic material

3. The virus is destroyed when the water-shunning tails of the soap molecules wedge themselves into the lipid membrane and pry it apart.

ILLUSTRATIONS: GREG BARTON, GNÁC CAPEK

Lipid membrane and other proteins

antibacterial have “active ingredients” like triclosan and chloroxylenol, but these ingredients have been controversial. Back in 2016, after manufacturers were unable to demonstrate that they were safe for long-term daily use, or indeed any better than plain soap, the FDA in the US banned 17 chemicals including triclosan and another antibacterial called triclocarban – so you won’t find them in soaps any longer. However, you might still come across other ingredients such as L-lactic acid in those soaps marketing themselves as “antibacterial”. But most antibacterial soaps now avoid using these controversial ingredients. “Some antibacterial formulations that are sold actually just have an ethanol in them,” Thordarson explains. “In a sense, they’re basically taking soap and hand sanitiser and mixing them. That’s it, really, and it works quite well.” Ethanol works differently to soap by denaturing the spike protein on the outside of the virus. Thordarson likens it to an earthquake, where everything is shaken so much that bacterial and virus coatings just fall apart. Having both ethanol and soap working together creates a formidable team. Although soap by itself can destroy the coronavirus no problem, other viruses and bacteria have more solid coatings, and ethanol and soap together can remove more types of bacteria and virus from your hands. You’d think that all this cell denaturing might be an issue for us too, considering our skin is also made of cells with cell membranes, but in this case having lots and lots of cells comes in handy.

The outer layer of our skin – the stratum corneum – is made up of around 15 layers of flattened dead cells which lack cell membranes. Instead, they have a much hardier casing of structural proteins called a “cornified envelope” that amphiphiles don’t care for as much. This doesn’t stop soap from doing a little damage to some of the cells, but as the stratum corneum is constantly shed, we can afford to lose a few cells here and there. On the other hand, bacteria and viruses – with a cell count of one – don’t fare so well. As the research into COVID-19 has progressed, we’ve learnt that washing our hands with soap or sanitiser – although good – isn’t the only way to protect ourselves. But are we likely to see something better than soap in the future? Thordarson doesn’t think so. “It’s dirt cheap, it’s safe, it doesn’t do any damage to us, it doesn’t do any damage to the environment that we can see, and it breaks down quickly,” he explains. “I’m hard pressed to see how to make it better.”

JACINTA BOWLER writes about far-flung exoplanets, terrifying superbugs and everything in between. This is her first story for Cosmos.

4. Soap traps dirt and fragments of the destroyed virus in tiny bubbles called micelles, which wash away in water.

102 COSMOS MAGAZINE

FERRIS BUELLER ZEITGEIST

A mathematician goes to the movies Could Ferris Bueller’s day off have really happened? SIMON PAMPENA crunches the numbers.

A

s a kid I loved Ferris Bueller. As an adult I think he has all the makings of a sociopath. But back then I didn’t see such flaws. Instead I saw him as a teenage Robin Hood – taking from the old to give to the young, namely himself. But as much as I wanted to believe that a high school student could pack that much fun into just one day, the story needed to add up, numerically speaking. Yes, I am well aware this classic teen movie is a work of fiction. But I was interested in knowing if Ferris and company could actually have crammed in as much as they did during the time that they had. That’s all. And yes, this is my idea of a good time. The deadline we have is Ferris’ parents returning home at 6pm. So let’s get started.

Morning

ILLUSTRATION: SIMON PAMPENA

Bueller residence John Hughes wrote the script for Ferris Bueller’s Day Off in just one week. It helped that Hughes was a Chicago native and had an intimate knowledge of the city. The school Ferris attended – Shermer High – and the house of his best friend Cameron were both real locations in Hughes’ childhood suburb. Very handy. Ferris’ house was also a real location, but a bit farther out – 3,280 km to be precise, in Long Beach, Los Angeles. Oh dear. Falling over at the starting line! But not to worry – Cameron’s house happens to be

a perfect place to start our timeline. We just need to work out what time that was. By the middle of second period of the school day, Ferris had just stepped into the driver’s seat of a rare 1961 Ferrari 250 GT California Spider. According to the Chicago public school timetable this puts us at 9:30am. “Che bella.” Time to swing by the school and pick up Ferris’ girlfriend, Sloane.

9:45am

Shermer High School The shortest route from Cameron’s house to their high school is 12 km. Given that the journey was in a 30 mi/h (48 km/h) speed zone and their car could accelerate from 0 to 100 in 6.3 secs, I estimate that they got there in 15 minutes. They spent 2 minutes at the school and then they were off to the big city. This mid-morning transit takes approximately 45 minutes, so let’s put them in downtown Chicago by 10:30am.

10:30am

Downtown parking garage Here’s another real-world film location. The carpark used in the film was only 580 m away from their first port of call. So far, so good. After handing over their US$110,000 car to dubious parking attendants, it’s exactly a 5-minute walk to Chicago’s tallest skyscraper, Willis Tower, as long as they averaged a brisk 6.96 km/h. Let’s say they spent 20 minutes here before power-walking another 5 minutes (or 748 steps) to their next stop, the Chicago Board of Trade. Here they watched some 1100 pit traders making deals via a trading sign language combining cosmosmagazine.com 103

The plan to wipe the extra 240 km from the odometer by driving in reverse presents us with a serious plot hole. 34 individual hand signals. But as fascinating as this sounds, research puts the maximum teenage attention span at 20 minutes, so by 11:20am they’d have had enough of hand-tohand capitalism and started thinking about lunch. Time for a fancy French restaurant somewhere north of the city.

12:00pm

we can estimate that they have been there at least 100 minutes. If we throw in just half of the sixth innings, then the whole time at the stadium amounts to 110 minutes. Given that at Wrigley Field there are approximately 17,000 seats in range of a foul ball and each person could cover an area of nine seats (their seat + one seat in every direction), it puts the

king for a day. However, this life-changing moment must be over in 25 minutes. That’s all. Sorry, folks. We’re running out of time.

4:50pm

Glencoe Beach Calder’s Flamingo is 580 m from the parking garage – the same distance that the parking garage was from Willis Tower! Unfortunately, numerical symmetry isn’t proof for meeting the 6pm deadline, so we must keep calculating. Another 5-minute walk has us back in the Ferrari by 4:20pm. Then it’s a 30-minute drive to their next location, Glencoe Beach, where each of

Chez Quis

1:25pm

Wrigley Field After lunch we find our truants off to a game of baseball at Chicago’s iconic Wrigley Field. Day games during the 1980s didn’t start until 1:25pm and a trip from the restaurant to the stadium would only take 15 minutes in the early afternoon. This allows 70 minutes for lunch, easily accommodating the 600 chews required for starters, mains and desserts – 55 mouthfuls, 13 chews per mouthful. Splendid! Now to the ball game. A whole game usually takes three hours, which would blow out our entire timeline. However, during a scene in a downtown bar, a game is playing on TV when a sportscaster announces: “Runner on first base, nobody out. That’s the first hit they’ve had since the fifth inning…” This is followed by Ferris catching a foul ball. Eureka! Their game has already had at least five innings. If an innings takes 20 minutes on average, then 104 COSMOS MAGAZINE

odds at 1 in 1,889. With the average game producing 15 foul balls by the fifth inning, Ferris had a 1 in 126 chance of catching at least one foul ball… But the main prize is the 6pm deadline and there’s a lot to pack in before then.

3:25pm

Art Institute Leaving Wrigley Field by cab at 3:15pm gets us to The Art Institute of Chicago in 10 minutes. Inside the gallery we only have time for a whirlwind tour of modern art – 15 minutes tops. This has them out on the street by 3:40pm and only a short walk from a German-American Parade taking place a few blocks away.

3:50pm

Twist and Shout We can place Cameron and Sloane at a public art piece known as Calder’s Flamingo just before they discover Ferris on a parade float. This is situated only five minutes by foot from the art museum. However, in the film they are stuck in a cab… eek! Walk, you lazy fools! We can allow 10 minutes in the cab before Ferris ascends a float to become

the Ferrari’s wheels rotate 8250 times to cover the required 38.3 km. It’s only a small addition to the 240 km – or 51,720 wheel rotations – already accumulated by the carpark attendants’ joyride that our trio has just discovered. This realisation induces the catatonic episode in Cameron, during which his blink rate dropped from 12-15 blinks/min down to zero. Here, we can only allow 10 minutes.

5:05pm

Some random jacuzzi Next we see Ferris and Sloane relaxing in a jacuzzi trying to motivate an unresponsive Cameron to join them. This location isn’t given any context in the film and our timeline is getting super tight! Let’s give

MAPS: SIMON PAMPENA

No self-respecting fine-dining establishment would serve meals before midday, so we can’t feed our trio any earlier than 12:00pm. That gives them 40 minutes to make their way to the lunch spot – Chez Quis. This was never a real restaurant, but nonetheless a real location only 3.54 km from the Chicago Board of Trade. These 40 minutes are covered via a leisurely 5.31 km/h stroll from the Chicago Board, burning a respectable 200 calories (837 kJ) each in the process. This means our teen heroes could arrive bang on 12:00pm, with big appetites and primed to steal a booking from Abe Froman, “Sausage King of Chicago”. The morning timeline fits perfectly. Now for the afternoon.

FERRIS BUELLER ZEITGEIST

them 5 minutes to get there and 15 minutes in the water. However, the scene is problematic, as a three-person 1,000L jacuzzi can, at best, heat up at a rate of 3˚C per hour. In 15 minutes that’s a measly 0.75˚C. Perhaps the offer of a cold jacuzzi was enough to keep Cameron out of the water? Luckily for us there isn’t time to worry about it too much since we need to get back to Cameron’s house – at most five minutes away.

5:25pm

Cameron’s house Finally we have arrived at the climactic scene: a vintage Ferrari jacked up and humming

in reverse. If we get to Cameron’s garage by 5:25pm we only have 30 minutes left in the budget for the Ferrari’s destruction. Yet their plan to wipe the extra 240 km from the odometer by driving in reverse presents us with a serious, possibly terminal, plot hole. The Ferrari’s factory specs have the reverse gear ratio at 13.5 and the redline rpm at 6,500 which, when combined, means their car had a top speed of 61 km/h in reverse. This means for their plan to work they would have needed at least 3 hours and 56 minutes. Luckily we are saved from this mathematical howler by the Ferrari launching backwards through a glass wall. Phew. Time to bring it home.

5:55pm

Sloane’s watch When Ferris says goodbye to oS Sloane he looks at her watch. It’s 5:55pm. m Only five minutes to get home before his hi parents. This final scene really needss iits own detailed analysis, but having been ee thoroughly entertained up to this point, po I am happy to accept that it was achievable. ach But more importantly, everything yth leading up to 5:55pm, excluding some om minor mathematical indiscretions, was also achievable. Which, I have to admit, comes as a big surprise. Yet perhaps it was to be expected. Hughes’ masterpiece was set in a city he understood innately. Like a London cabbie he had a mental map of each location when writing and editing his film. And within those constraints he crafted a brilliant story

of mid-’80s teenage rebellion. And we’re glad he did, because there is no way anyone could pull a Ferris Bueller’s day off today. The Ferrari would have its own tracking device. The French restaurant would have image-searched “Chicago Sausage King” to verify Ferris’ claim. And social media would have exploded during Twist and Shout. And that would be it. Ferris Bueller’s day over! But instead we have a rite of passage for any teen wondering what life would be like if they could stop and look around once in a while… and the opportunity for a nerd like me to overanalyse the whole thing on a spreadsheet. Thank you, Ferris Bueller, you’re still my hero.

SIMON PAMPENA is a journalist, presenter and Australian Numeracy Ambassador. cosmosmagazine.com 105

ies k s t h nig p u hy g n w i t s h r e g i nd el r o a w s y O . E la y t p Y r s i a A d p ND ne the o A r n i d M o j g A . n o Danci d the world een slow t aroun tralia has b Aus

DRONES ZEITGEIST

A

s Australia burned through 2019’s devastating Black Summer, a Change.org petition circulated calling for the cancellation of Sydney’s New Year’s Eve fireworks show. While the spectacular display of pyrotechnics has been an annual tradition since 1976, some thought it would be tasteless amidst the ongoing bushfires. There were also general concerns about the safety of shooting off sparks in hot, dry weather. “It’s time for change,” wrote organiser Linda McCormick on the site. “Australia has seen enough fire!” The show ultimately went ahead, however the petition gathered over 370,000 signatures and ignited conversations about potential alternatives. One of the most popular suggestions was drone light shows: coordinated aerial displays featuring numerous quadcopters working together to create shapes in the sky out of points of light. “You can’t rely on people to be responsible with fireworks,” signatory Susan Fahey commented under the petition. “Fireworks displays are unnecessary when you can have amazing drone light shows.” It sounded like an obvious solution. Reusable drones are much less of a fire hazard than fireworks, while potentially being as dazzling. However, making the pivot to drones is much more complicated than it may initially appear.

VCG / GETTY IMAGES

Drones Down Under “You won’t find any experts in Australia on drone light shows,” says Global Drone Solutions CEO Mahmood Hussein. “The simple reason is that this is relatively new technology.” Despite its international name, Global Drone Solutions is an Australian company that offers training to domestic drone pilots. Yet while drone light shows have been a possibility for years, the company doesn’t cosmosmagazine.com 107

Drone show and tell The sight, sound and gunpowder smell of fireworks will always provide its own unique thrill. Yet drone light shows offer a level of control, customisation and complexity that pyrotechnics simply cannot match. To perform a drone show, multiple quadcopters

coordinate to fly in programmed, preset patterns, tracing out shapes in the sky that are often choreographed to music. With lights attached to the drones, the result looks similar to brightly coloured moving stars or animated pixel art at a very low resolution. “Drone shows can be fully customised to create anything imaginable, and also offer significant environmental advantages,” says Ryan Sigmon, co-founder of Firefly Drone Shows, based in Michigan in the US. “We’ve noticed large brands gravitating towards drone light shows, as their messaging can be clearly recreated in the sky. We’ve also seen large cities adopt drone light shows to avoid polluted air and debris that is left behind from large pyrotechnic displays.” Though drone light shows vary significantly in size, Verge Aero CEO Nils Thorjussen considers 150 to 200 drones to be the “sweet spot”. The Pennsylvania-based

“Drone show animation is a new field. That means there are no best practices or tutorials out there on the internet. Every trick or approach you come up with is an innovation.” 108 COSMOS MAGAZINE

company has years of experience in these events. “One can create a lot of content with this and it’s a manageable number,” Thorjussen says. Both Verge Aero and Firefly top out their performances at 300 drones, though Firefly plans to increase that count soon. Still, Sigmon agrees that large numbers of drones aren’t needed to create an impact. “Our clients have realised that 100 or 200 drones can go a long way from a creative standpoint,” he says. “Our 100 drone performances typically include formations spanning around 150 metres.” Most light show performances use fleets of small quadcopters – helicopters with four rotors. Each quadcopter is mounted with a bright LED light which can turn on and off, as well as change colour when needed. The drones are also relatively lightweight, as they don’t have to carry cameras or other equipment. Intel’s Shooting Star drones weigh just 330g – less than a jar of Vegemite. This means they significantly differ in size, shape and weight from drones used for surveying, photography or delivery. The lighter a drone, the less power it needs to get it in the air. However, it then becomes a question of balance. Drones with

CLOCKWISE FROM ABOVE: SUHAIMI ABDULLAH / GETTY IMAGES. INTEL CORPORATION X2

yet offer any courses in this specialised field. Singapore ushered in 2020 with a 500-drone light show, and in September a display of 3,051 drones in China set a record for the most simultaneously airborne unmanned aerial vehicles. Drones appeared at the US’s 2019 Super Bowl and at President Biden’s victory speech in November 2020. But Australia remains largely focused on exploring more immediately practical functions for drone technology. “Some of the popular applications are in mining, oil and gas exploration, construction, agriculture and infrastructure industries,” says Hussein. “The number of drone applications has exploded over the past five years.” Staging light shows has been a far less common use of drones in Australia so far. Some shows have been done: in 2016, for example, Intel staged a 100-drone show during Vivid Sydney, flying a stylised silhouette of the Opera House over Sydney Harbour. But there are numerous barriers stalling adoption, including high costs, strict regulatory requirements and the fact that the technology is still in its infancy. Still, Hussein believes Australia’s drone use is only going to grow. Having been in the drone industry for seven years, he optimistically projects drone light shows will soon gain a skyhold in Australia. “I can see fireworks being replaced in the next few years, as a number of large organisations and universities have started to invest in this area, the cost of drones and software is becoming less expensive, and computer power and technology like 5G will certainly make it a more viable alternative,” says Hussein. “And we must not forget, it is environmentally friendly.”

DRONES ZEITGEIST

Choreographed drones fire up the celebrations in Singapore (left); Folsom, California (right); and Guangzhou, China (previous spread).

new field. That means that there are no best practices or tutorials out there on the internet. Every trick or approach you come up with is an innovation.” With no standard approach, there is no right or wrong way to stage a show. Even so, there are common steps that most displays tend to share.

NEXT PAGE, FROM TOP: LIU BO, DENG FEI / GETTY IMAGES

1. CLEAR SKIES AHEAD larger batteries store more power, but they also use more power due to their weight. Drones with smaller batteries have less power, but their lighter weight means they don’t need as much juice to get airborne. This dichotomy dictates how long drones can stay in the air, and thus how long a performance can be. Verge Aero’s shows average around 10 to 12 minutes, their drones lasting aloft for 15 minutes maximum. Firefly offers drone shows up to 15 minutes long. “Battery life is the primary driver behind show lengths,” said Sigmon, noting that Firefly is developing new hardware to push flight lengths to over 20 minutes. Fifteen minutes doesn’t seem long. But the Sydney New Year’s Eve fireworks usually run for around 12 minutes, demonstrating that it’s more than enough time to dazzle a crowd. It all depends on what you do with it.

Light club In theory, a drone light show looks like a simple matter of pre-programming a few hundred quadcopters and letting them fly. In fact, it is an extremely complex job involving a lot of emergent technology, as Martins Upitis, lead drone show animator at Base Motion, has explained. “Drone show animation is a

“We always start by confirming a location that meets our safety requirements,” says Sigmon. This isn’t as simple as finding a clear patch of sky, as the relevant aviation authorities must be satisfied. In the US, that’s the Federal Aviation Authority, whose regulations forbid drones being flown over people and crowds, and require a large safety perimeter around any performance. “This sometimes makes it challenging flying near densely populated areas,” says Sigmon. “We often close down waterways or roads in order to secure our safety zones.” The Civil Aviation Safety Authority (CASA) enforces the laws in Australia. Anyone flying drones for commercial purposes must hold a remote pilot licence, as well as either hold or work for an organisation that holds a remotely piloted operator’s certificate. And as drone light shows involve more than one drone, those hoping to stage one also need to obtain specific approval from CASA. “It is likely drone light shows will become more common and CASA will carefully assess applications as they are made,” CASA’s Peter Gibson told Cosmos. “Our aim is to not get in the way of innovative drone use, while of course ensuring public safety is not put at unacceptable risk.”

2. GETTING WITH THE PROGRAM If you do manage to run the regulation gauntlet and are confident the cops won’t shut down your party before it starts, the performance must then be storyboarded. It’s during this step that the displayed shapes, music and synchronisation are worked out, whether it’s a movie logo, marriage proposal, or giant internet meme. A computer animation is then created from this storyboard to provide a preview of the show, allowing the designers to visualise and tweak it before the drones ever take flight. This also lets them sort out any problems, potential collisions and even potential viewing angles. “Our animation previews are verbatim to what will be seen in the night sky,” says Sigmon. In fact, many of the basic steps involved in creating a drone light show are cosmosmagazine.com 109

strikingly similar to those in making an animated film. 3D animation software is frequently used, with programs such as the Drone Show Software translating animations directly into commands and flight paths for the drones to follow. A lack of industry standard tools has led companies such as Firefly and Verge Aero to develop their own software, but the general principles are the same. “It’s exactly like 3D animation,” says Thorjussen. “The software does all the work!” Despite the similarities, switching from Disney to drones is no simple matter, and there is still a steep learning curve for animators who wish to make the leap between mediums. Like pinning a dress around a magazine model, 3D animators can use angles and framing to tuck messy elements out of sight, but there’s nowhere to hide in drone animation. Each show must be designed to be viewed from all angles, so animators need to be sure they don’t have a bad side. Pair this with the relative dearth of jobs in drone performance, and there isn’t much incentive to switch careers – just one more factor helping keep the industry small and scarcity high.

3. FLYING HIGH Coordinating 150 pilots to fly 150 drones at once would be a logistical nightmare. Fortunately, not every drone in a light show needs its own individual pilot. Instead they are controlled by a central computer, relying on emergent swarm technology to get the job done. As such, the ground crew looking after the performance only needs to be relatively small. Swarm technology enables multiple drones to communicate with each other like bees, working together towards a shared end goal rather than having each drone’s flight path individually prescribed. Using GPS or radio frequencies to position themselves, drones can wirelessly chat to each other to ensure they maintain their spacing and avoid collisions. They can also determine which of the drones is best suited for each job required to bring the show to life. All this automation doesn’t remove humans from the equation. Aside from the fact that CASA requires a pilot to be present, people still need to position the drones and be on hand for any last minute adjustments. 110 COSMOS MAGAZINE

“Though the show is pre-programmed, the launch and position of the show must be calculated at the location,” says Sigmon. “Various on-site tests are conducted to ensure the audience will have the best experience.”

Pie in the sky? As dazzling as drone light shows may be, there are significant barriers preventing them from being more widely employed. In addition to strict regulations and a low supply of workers with relevant training or experience, the prohibitive cost of drone performances is a powerful deterrent. Fireworks displays can come at a fraction of the price. Small drone light shows can cost around $25,000 according to Thorjussen, with average prices ranging from $65,000 to $130,000. Intel’s performances start at $130,000 for 200 drones, and that only involves 2D shapes. “The costs of a drone light show tend to vary as there are always many factors involved,” says Sigmon. “The quantity of drones flown for an event, as well as the

DRONES ZEITGEIST

ANATOMY OF A QUADCOPTER Many drones make a light show work. But one operator can rule them all – with the right pre-programming. Drone propeller

Drone motor

GPS module

Flight LED

Electronic speed controller

Forward obstacle avoidance sensor Downward Downward ultrasonic obstacle avoidance sensor sensor

Power port module Axis gimbal

Formation drone flying over Shenzhen Bay in China late last year (left and below) dazzled spectators – without the smoke and din.

Drone camera Drone flight controller

amount of custom animation, tend to be our biggest drivers.”

The future of fireworks Though many spectators see drone light shows as an alternative or competitor to fireworks, not all industry professionals consider it a matter of one or the other. Singapore may have celebrated New Year’s Eve with a giant Merlion made of drones floating above Marina Bay, but it appeared alongside the country’s more traditional fireworks display. Rather than supplanting pyrotechnics, drone light shows are viewed as a complement to their fiery predecessors – a little added spice. “Firefly never set out to replace or compete against the pyro industry,” says Sigmon. “Instead, we wanted to introduce a completely new form of entertainment to the world and allow consumers to make the decision for themselves.” “I think that, over time, budgets will shift from fireworks to drones,” says Thorjussen.

“Firework shows are already being replaced. This trend will only accelerate. But that doesn’t mean that fireworks will go away any time soon.” It will likely be at least a few more years before drone lights shows are even incorporated into Sydney’s New Year’s celebrations, much less replace the fireworks entirely. Even so, they might join the party sooner than you’d think. “In situations such as the New Year’s Eve displays where much of the activity is on the harbour, the risks may not be too complex to successfully manage,” says Gibson. There are still many hurdles for drone light shows to overcome before they’re commonplace. Tradition is difficult to break, and new technology takes time to refine. But the future always arrives more quickly than we expect.

AMANDA YEO is a Sydney-based writer and lawyer, as well as co-creator and host of tech podcast Queens of the Drone Age. This is her first story for Cosmos. cosmosmagazine.com 111

WHERE IN THE COSMOS?

MIND GAMES

Who Said?

NO.17

“Do not look at stars as bright spots only. Try to take in the vastness of the universe.” (5,8)

Send us a pic of where you’re reading Cosmos to win a prize pack!

WHAT BETTER SPOT TO WATCH OUR FABULOUS WORLD IN ACTION AND ENJOY SCIENCE? This issue we’re celebrating the next generation, enjoying the universe in our travel-limited season. As Peter Nolan says, what better time for son Lewis to read about deliciousness as a driver of evolution (Issue 89) than over breakfast? And at top right, Anne Emery sent this snap of Evelyn enjoying the last issue of Cosmos at Grandma and Grandad’s.

COMPETITION

QUESTION Whose Law?

Decode where m = m

HINT: It is an empirical law in zoology proposed in 1876.

Email your answer to: [email protected] with your name and address by 31 July 2021. Three correct entries will win a copy of Pirate Queen: The life of Grace O’Malley by Judith Cook, published by New South Books. 112 COSMOS MAGAZINE

INSTRUCTIONS Answers to each of the clues in columns 1 to 13. Row V reveals the answer.

CLUES AND COLUMNS What is anyone who suffers from chronic sleeplessness? (9) What is the loss of speech or symbolic formation due to a lesion on the central nervous system? (7) 3 Who invented the spinning jenny? (10) 4 What is the largest continuous area of tropical rainforest on the Australian mainland? (8) 5 What is the psychological condition marked by suspension of sensations, muscular rigidity and often the loss of contact with the environment? (9) 6 What are used for determining the total concentration of dissolved salts and sugars in blood or urine samples? (9) 7 In which profession were Alfred Hitchcock, Yasser Arafat and Boris Yeltsin qualified? (8) 8 What are any of the ornithischian dinosaurs that walked erect on their hind legs? (10) 9 What is the Australian plant of the genus Corymbia, Angophora and Allosyncarpia among others? (8) 10 Easter is celebrated on the first Sunday after which full moon? (7) 11 What is the wave which propagates through an electrically conducting fluid in the direction of an applied magnetic field? (6,4) 12 Which era begins with the start of farming and ends when metal tools became widespread? (9) 11 Which law, named after a Dutch mathematician, states that when a ray of light is refracted at a surface separating two media, the sine of the angle of refraction to the sine of the angle of incidence is a constant? (6,3) 1 2

ENDPOINT SOLUTIONS: COSMOS 90 CODEWORD

Cosmos Codeword 22

7

3 13

14

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2

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1

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A N A O U T S I C A L I J V A R I G O I N

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U W Q

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I C A B S E O X C R F U L A Z F E L D E D S P R R E E S S I M I L A E N E U R O T O Q G H T U R E E L A N O H T C O R N O Y E E R Y A M P G

18

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N E O C O R T E X B C U E

C E X I C I U T E E K I N O O W A O B L R E

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1

NO.17

WHO SAID? Arvind Gupta An Indian toy inventor and science author, Gupta’s TED Talk “Turning Trash into Toys for Learning” has almost two millions views.

NO.17

COMPETITION WINNERS

INSTRUCTIONS Using the clues below place the numbers 1 to 16 correctly in the grid. How many clues do you need? LEVEL 1 – CHIEF SCIENTIST 1 Every single-digit prime is adjacent or diagonal to that number of composite numbers. 2 The row ending with three primes is on opposite ends to the row beginning with three squares. 3 The upward sloping diagonal has a range equal to the square root of its first number.

4

5

Column 3 is the only column which does not contain a number three times greater than another directly below it. The sum of the first two numbers in Row A is equal to the second number in Column 2.

LEVEL 2 – SENIOR ANALYST 6 All the non-square even numbers below ten are in Column 4. 7 There are two multiples of 5 in Row B. LEVEL 3 – LAB ASSISTANT 8 The largest number ends Column 3. 9 The number beginning Row A is neither prime or composite.

Congratulations to our three lucky winners, who receive a Cosmos prize pack: Wendy Scott, Qld Colleen Madeley, WA Greg Smith, NSW

ANSWER: When a depositional environment “migrates” laterally, sediments of one depositional environment come to lie on top of another. Johannes Walther

cosmosmagazine.com 113

PROFILE GALACTIC ARCHAEOLOGIST

Ioana Ciuca GALACTIC ARCHAEOLOGIST fell in love with the universe: on the afternoon of August 11, 1999, when a total solar eclipse threw Romania into shadow. “I was with my mum and my brother in western Romania, and we didn’t have much,” Ciuca explains. They couldn’t get specially filtered solar eclipse glasses – but luckily, Ciuca says, her mother “was sort of a Tesla inventor, so she took a bucket of water and I saw the eclipse reflected in the water”. She was six years old, and that memorable day grew into an obsession with astronomy that stayed with her, leading her to the UK to study astrophysics and gain her PhD. Ciuca confesses that part of her wanted to keep this story close to her heart. “But then I think, there are so many kids out there who think, ‘Oh I couldn’t ever do astronomy because it’s so hard to get there, and maybe we don’t have the tools and skills’,” she says. “I think that people should still try – that there is a way.” She has now taken up a position at the Australian National University, where

114 COSMOS MAGAZINE

she works as an ASTRO 3D Fellow on the GALAH (Galactic Archaeology with HERMES) project – though unfortunately COVID-19 means that for now, she’s working from Romania. “My research field is galactic archaeology, which is a relatively new field that was facilitated by the Gaia mission,” Ciuca explains. By drawing on Gaia’s data on billions of stars, galactic archaeology aims to unravel the mysteries of the formation and evolution of galaxies. Ciuca’s research involves pinning down the ages of stars using machine learning algorithms, but another cosmic enigma lurks at the back of her mind. “I have a vested interest in finding dark matter,” she says. “I believe that with Gaia, we can detect the features of dark matter haloes.” While impossible to directly observe, dark matter does exert gravitational sway on other objects – so as Gaia watches and precisely maps countless stars, it may spot strange motions that will illuminate this unknown substance. Ciuca says there are three main reasons

“My mother was sort of a Tesla inventor, so she took a bucket of water and I saw the eclipse reflected in the water” driving her to continue studying astronomy. The first is a curiosity about the world and a desire to advance human knowledge, while the second is to pave the way for the next generation. But the third reason, she says, is the most important: “If you observe the galaxy from Romania, the United Kingdom and Australia, you see different parts of it – but it’s the same galaxy. I feel like studying astronomy allows us to build a community and help each other as a species, to come together and try to do something fascinating.”

READ ABOUT THE GAIA SPACE TELESCOPE ON PAGE 66

GOH KENG CHEONG / GETTY IMAGES

I

oana Ciuca remembers the moment she

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