National Geographic

03.2021 We can’t get enough of the red planet





FURTHER MARCH 2021 CONTENTS On the Cover We’ve been fascinated for millennia by Mars, seen here in images taken by (from top) the European Space Agency’s Mars Express, and the Viking Orbiter 1. EUROPEAN SPACE AGENCY—ESA; NASA/USGS PROOF EXPLORE 15 THE BIG IDEA 6 27 Natural Disasters? Maybe climate change DISCOVERY harms should be called what they are: man- From Lethal Trap made natural disasters. to Artful Treasure Snares that once killed BY ELIZABETH KOLBERT Uganda’s wildlife now support communities. DECODER BY JANI HALL Life After Fire Ecosystem engineers, PHOTOGRAPHS BY black-backed wood- peckers are built for ESTHER RUTH MBABAZI life amid partially burned trees. BY TAY LO R M AG G I AC OMO The ‘Train Ladies’ ALSO AT L A S of Ukraine A tradition as old as rail Ancient Amphibian Setting Rivers Free travel in Ukraine, these Plants in Disguise Human influences have safety signal officers Moonlit Line Walk negatively affected the work in tiny houses at flows of most of Earth’s rail crossings, and help 10 longest rivers. keep things on track. BY HEATHER GABRIEL SMITH PHOTOGRAPHS BY AND CHRISTINA SHINTANI SASHA MASLOV ALSO Interpreting History

FEATURE S Our Obsession Imprisoned A Line in the With Mars Missions While Innocent Mountains Since sky-watchers in Thanks to scrutiny of The story behind boun- the third millennium the actions of prose- daries on the world’s B.C. described it as a cutors, public defend- highest battlefield. “wandering star,” Mars ers, and police, as well has fascinated people as advances in DNA BY FREDDIE WILKINSON on Earth. It so intrigues analysis and other sorts us that by this month, of forensic testing, PHOTOGRAPHS BY CORY 11 spacecraft and rovers 182 people have been are expected to be on found innocent and R I C H A R D S . . . . . . . . . . . . . . . . . . . P. 94 or near the red planet. exonerated from death row since 1972. Greyhound Racing BY NADIA DRAKE Critics of the dogs’ BY PHILLIP MORRIS treatment spur the end PHOTOGRAPHS BY of tracks, race betting. PHOTOGRAPHS BY CRAIG CUTLER AND BY CRAIG PITTMAN MARTIN SCHOELLER SPENCER LOWELL PHOTOGRAPHS BY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. 66 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. 38 ERIKA LARSEN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. 122

M A R C H | FROM THE EDITOR DEATH-ROW The Costs of Wrongful EXONERATIONS Convictions BY SUSAN GOLDBERG PHOTOGRAPH BY MARTIN SCHOELLER SINCE 1972, 180 MEN AND TWO WOMEN lives with varying degrees of success. Derrick Jamison (above) Schoeller has a unique perspective spent 20 years on death row in the United States have been freed before his wrongful conviction from death row after being found inno- on how they do it. For another recent was overturned. He’s now a cent of the crimes for which they were project, he has been taking portraits of member of Witness to Inno- sentenced to die. Martin Schoeller, a now elderly survivors of the Holocaust. cence, the anti–death penalty longtime National Geographic contrib- He’s found that the two groups have group co-founded by Sister utor known for his haunting, close-up something important in common, he Helen Prejean and death-row portraits, has photographed, filmed, told me: “They are able to forgive. There exoneree Ray Krone. Martin and interviewed 17 of them. are so many reasons that you can be Schoeller (below) raised hateful and mad at people, but you have funds for the group as part Schoeller brought these photos to us to have the ability to forgive. Otherwise of his project to photograph and our colleagues at ABC News (both it just eats you up,” he said. “The people men and women who’ve organizations are owned by The Walt who can’t get to that conclusion emo- been freed from death row. Disney Company). His goal: He wants tionally, they don’t make it.” Schoeller’s project will be people to reconsider their support for the subject of an ABC News the death penalty, which today in Amer- For most of National Geographic’s prime-time special this spring. ica can be imposed by 28 states, the 133 years, photography has been cen- federal government, and the military. tral to our mission. Martin Schoeller’s Schoeller hopes that people who see his portraits remind us why: Because even photos “feel like ‘This could have been in a streaming-media age, still photos me—and they were sentenced to death can reveal indelibly powerful stories. for something they didn’t do.’ That’s the reason I did this: To create work that will Thank you for reading National change some people’s hearts.” Geographic. j Whether you support or oppose the death penalty, there’s no question that Schoeller’s portraits and stories of exonerated former prisoners are pow- erful. These people were caught up in a Kafkaesque nightmare, often caused by police or prosecutorial misconduct, or witnesses who lied or were mistaken. Most of the wrongly convicted had poor legal representation; dispropor- tionate numbers of them were peo- ple of color, from low-education and low-income backgrounds. They sat on death row, typically in solitary confine- ment, sometimes for decades. They missed their own parents’ funerals. Their children grew up without them. Ultimately, they were freed by DNA evidence, better lawyers, or events that caused the truth of their innocence to come out. After all that, most are managing to go on, reclaiming their SCHOELLER PORTRAIT: KATHY RYAN

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PROOF NATIONAL GEOGRAPHIC PHOTO GRAPHS BY SASHA MASLOV LOOKING AT THE EARTH FROM EVERY P OS SIBLE ANGLE 6 NATIONAL GEOGRAPHIC

UKRAINE’S ‘TRAIN LADIES’ Along the country’s railroad system, tiny houses shelter signal attendants who help keep travel safe. VOL. 239 NO. 3 Railway attendant Inna Oleksandrivna Manoylenko, at work on the outskirts of Kyiv, is one of thousands of Ukrainian railway employees who signal to passing trains and keep impatient people off the tracks. MARCH 2021 7

PROOF Nataliia Yuriivna Pylypenko passes time between trains by tending the garden at this trackside house, which is owned by the Ukrainian railway. 8 NATIONAL GEOGRAPHIC

Signal jobs like these have long been held by women, a holdover from the Soviet era when the govern- ment influenced workplace gender roles. As the women retire, some men are taking their place. MARCH 2021 9

PROOF Kononivka Station, 113 km, is one of many stations known by their name and distance from a main city. That usually means Kyiv, but some retain their Soviet-era distance measure from Moscow. 10 N AT I O N A L G E O G R A P H I C

No two railway houses look the same, but common traits are their small size—a single-story may be about 225 square feet—and their location near rail crossings. The workers’ lives revolve around train schedules. M A R C H 2 0 2 1 11

PROOF THE BACKSTORY FROM TINY TRACKSIDE HOUSES, UKRAINIAN SIGNAL OFFICERS KEEP TRAINS RUNNING SMOOTHLY AND MOTORISTS SA F E . MANY OF SASHA MASLOV’S best changing. The officers are no longer childhood memories are connected all women, and the Ukraine Railways to trains. Every vacation, every trip to agency, Ukrzaliznytsia, has expanded another city, he’d stare out the window its hiring to try to bring more young to see the texture of his country in the workers into the unglamorous but apartment buildings and shops and stable work. cars waiting for the train to pass. And every so often, he’d see a tiny house In a world of high-speed trains and with a woman standing by it, holding automated crossings, rail attendants a yellow flag. today may spend less time signaling to trains than policing and warning “Ukrainian railroad ladies,” as motorists. “Ukrainians are notori- Maslov calls them in his portrait series, ously not law-abiding,” Maslov com- are a cultural tradition that feels as old ments. “If there is no watcher, people as rail travel in Ukraine. The workers will go around the barriers to beat a are tasked with sending flag-based moving train.” signals to conductors of approaching trains. A folded yellow flag means all The life can be monastic. In between clear ahead. An unfolded flag means trains, the workers tend gardens, com- reduce speed and proceed with cau- plete chores, and fill out paperwork. In tion. A red flag—or a flare shot into the one house, Maslov saw a notebook in air—means to stop moving entirely, as which an attendant had taken down a hazard is ahead. the license plate numbers of cars that ran through barriers. She sent the list Some aspects of rail officer life are to the police. — DA N I E L STO N E Ukraine’s colorful crossing houses provide a public service and are a cultural touchstone.

EXPLORE IN THIS SECTION Woodpeckers and Fire Moonlit Rope Walk Artworks From Snares History in Their Words ILLUMINATING THE MYSTERIES—AND WONDERS—ALL AROUND US EVERY DAY NATIONAL GEOGRAPHIC VOL. 239 NO. 3 When ‘Natural’ Disasters Aren’t PERHAPS FIRES, STORMS, AND VIRUSES FED BY CLIMATE CHANGE SHOULD BE CALLED WHAT THEY ARE: MAN-MADE NATURAL DISASTERS. BY ELIZABETH KOLBERT A AT A N E W S C O N F E R E N C E in mid-August of last year, California’s governor, Gavin Newsom, announced that there were 367 “known” wildfires burning in the state. “I say ‘known’ fires,” Newsom said, “but the prospect of that number going up is very real.” A couple of days later the number did, in fact, increase, to 560. A few weeks after that, many of the blazes were still burning, and one—the Doe fire, north of Santa Rosa—had grown into the largest conflagration in California history. The smoke from the state was so bad that it veiled the sun in New England. By the time most of California’s flames had been put out in late November, at least 31 people had been killed and tens of thousands evacuated. Even as more than 15,000 firefighters were battling the California wildfires, Hurricane Laura was bear- ing down on Louisiana. As it passed over the Gulf of Mexico, it strengthened at a near-record rate. In just 24 hours it zoomed from a Category 1 to a Category 4 M A R C H 2 0 2 1 15

E X P L O R E | THE BIG IDEA storm. By the time it hit Cameron Parish, early in the morning of August 27, it was the fifth fiercest hurricane to make landfall in U.S. history. The storm caused at least 16 U.S. deaths and up to $12 billion in damages. Twenty years ago, crises like the Doe fire and Hur- ricane Laura could have been described as “natural disasters.” Thanks to climate change, this is no longer the case. Right around the time of Newsom’s press conference, the mercury in Death Valley hit 130°F, the highest temperature ever reliably recorded on Earth. A hotter, drier California is much more likely to burst into flames. The Gulf too is heating up, with dangerous consequences. Hurricanes draw their energy from the warmth of the surface waters and so are becoming stronger and more apt to intensify. I’ve been reporting on climate change for almost two decades, and I’ve come to think that we need a new term to describe these events. Perhaps we should call them “man-made natural disasters.” People now play such a dominant role on the planet, it’s said we live in a new geological epoch: the Anthropocene. By cutting down forests and digging mines and building cities, we’ve transformed half of the ice-free land on Earth. (Indirectly, we’ve altered half of what remains.) With our fertilizer plants, we fix more nitrogen than all terrestrial eco- systems combined; with our plows and bulldozers, we move around more earth than all the world’s rivers and streams. In terms of biomass, the numbers are staggering. People now outweigh wild mammals by a ratio of more than 8 to 1. Add in our domes- ticated animals (mostly cows and pigs), and the ratio’s almost 23 to 1. In the Anthropocene, all sorts of catastrophes straddle the line between man and nature. Many earthquakes, for example, are now triggered by human activity, in particular fracking. An unusually strong human-induced quake that shook Pawnee, Oklahoma, a few years ago was felt all the way to Des Moines, Iowa. And then there’s COVID-19. The virus that causes COVID seems to have origi- nated in horseshoe bats. It appears to have made the leap to people near the city of Wuhan, China, either directly or through an intermediate species that has yet to be identified. Pathogens have, presumably, been jumping between animals and humans for as long as both have been around. But for most of human history, such “spillover events” were limited in their impact. Infected populations didn’t move very far or very fast. With jet travel, a virus can now make it halfway around the world between evening newscasts. Within a month of the first confirmed cases in central China, COVID had reached at least 26 other countries. Soon it was just about everywhere, even such remote places as the Falkland Islands and the Kamchatka Peninsula. Just as with their predecessors, it’s hard to pre- dict when or where man-made natural disasters will strike. Still, the trend lines are clear. As people increasingly destroy other animals’ habitats and move species around the world, outbreaks of novel 16 N AT I O N A L G E O G R A P H I C

ILLUSTRATION: LEONARDO SANTAMARIA M A R C H 2 0 2 1 17

E X P L O R E | THE BIG IDEA diseases will become more common. Author (and TEN OR 20 YEARS FROM frequent National Geographic contributor) David NOW, L A ST YEAR’S RECORD - Quammen has put it this way: “We disrupt ecosys- BREAKING FIRES AND FLOODS tems, and we shake viruses loose from their natural WILL ALMOST CERTAINLY hosts. When that happens, they need a new host.” HAVE BEEN OVERTAKEN BY Often, that new host is going to be us. NEW RECORD BREAKERS. Meanwhile, as the climate continues to warm, engineering systems are ever deployed.” conflagrations will grow even larger and storms more Another school of thought argues that the new damaging. A recent study showed that in California, the frequency of dangerous “fire weather” days has world-altering technologies are likely to have much more than doubled over the past four decades. By the the same impact as the old world-altering technolo- end of the century, it could double again. Ten or 20 gies, only with higher stakes. Consider the example years from now, last year’s record-breaking fires and of chlorofluorocarbons. These compounds were first floods will almost certainly have been overtaken by synthesized in the late 1920s in the hope of solving new record breakers. As Andrew Dessler, a professor the problems caused by early refrigerants, such as of atmospheric sciences at Texas A&M University, ammonia, which were toxic. Billions of pounds of observed last fall, “If you don’t like all of the climate chlorofluorocarbons were produced before it was disasters happening in 2020, I have some bad news discovered, in the 1980s, that the chemicals were for you about the rest of your life.” destroying the ozone layer, which shields the Earth from ultraviolet radiation. What’s to be done? According to one school of thought, the best way to deal with human interven- Despite a global ban on chlorofluorocarbons, the tion in the natural world is to intervene better. Old chemicals still are being produced illegally, and technologies got us into this situation; new ones will every year a “hole” in the ozone opens up over the get us out. Advocates of this view note the extraor- Southern Hemisphere. Shooting reflective parti- dinary advances that are being made all the time, in cles into the stratosphere could further damage the fields ranging from computing to genetics to material ozone layer. It also could cause other problems that science. To make it easier to find treatments for have not been—and perhaps never can be—fully COVID-19, Chinese researchers genetically altered anticipated. Critics have described the very idea of mice to possess the same virus receptors as humans. solar geoengineering as “utterly mad,” “dangerous The scientists used a technique known as CRISPR, beyond belief,” and “a broad highway to hell.” which over the past few years has revolutionized gene editing. To combat climate change, engineers As for me, I feel tugged in both directions. The have built machines that suck carbon dioxide out of choice we face is not whether to change the world; the air. Today the numbers are limited, but perhaps that decision unfortunately has been made. The one day they’ll be as common as iPhones. decision going forward is how are we going to change it? Over the years I’ve interviewed scores of scientists, Alternatively, it’s been proposed that climate inventors, and entrepreneurs, and I’m continually change could be counteracted by blocking some of impressed by how ingenious humans are as a spe- the sun’s incoming rays. Researchers are working on cies. But then the wind blows in smoke from 3,000 technologies to brighten clouds, which would bounce miles away, and I’m reminded of how dangerous we more sunlight out to space. Another technique, are as well. j known as “solar geoengineering,” would spread reflective particles in the stratosphere, providing Elizabeth Kolbert is a staff writer for the New Yorker, a regular the entire planet with a kind of sunshade. contributor to National Geographic, and a two-time National Magazine Award winner. This essay is adapted from her new “Ironically, such engineering efforts may be the book, Under a White Sky. Her previous book The Sixth Extinction best chance for survival for most of the Earth’s nat- received the 2015 Pulitzer Prize for General Nonfiction. ural ecosystems,” Daniel Schrag, director of the Harvard University Center for the Environment, has written. However, he noted, perhaps the eco- systems “should no longer be called natural if such Making Sept. 9: The Doe fire became the largest in grim history California’s history. In 2020 “man-made natural Oct. 14: The Cameron Peak fire became the disasters” broke records. largest in Colorado’s history. Oct. 5-6: Hurricane Delta set a new record for the fastest intensification from a tropical depression to a Category 4 hurricane in the Atlantic Basin. Nov. 1: Super Typhoon Goni became the strongest tropical cyclone to make landfall, hitting the Philippines with winds of 195 mph.

DISPATCHE S BREAKTHROUGHS | E X P L O R E FROM THE FRONT LINES Sniffing out the deadly virus OF SCIENCE A N D I N N OVAT I O N Scientists are training working dogs to detect COVID-19–related compounds in human sweat. Sniffers such as Floki (right), an English springer spaniel at Australia’s University of Ade- laide, could be deployed to airports, hospitals, and other facilities worldwide to help screen for the virus. — H W * A DA P TAT I O N FOSSIL FIND Evolving to Evade ANCIENT BUG ZAPPER Harvest A N A LYS I S R E V E A L S F O S S I L I S T H E O L D E ST K N OW N For centuries in EXAMPLE OF A SLINGSHOT-TONGUED AMPHIBIAN. China’s Hengduan Mountains, herbal- A N A M B E R- E N T O M B E D F O S S I L with an ists have collected exquisitely preserved skull (left)—even Fritillaria delavayi some muscles intact—is the oldest known plant bulbs for example of a slingshot tongue, found in use in traditional amphibians called albanerpetontids. medicine. A recent Details about “albies” have been elusive; study found some another albie fossil previously was mis- F. delavayi have identified as its distant cousin the chameleon. But new analysis changed color by Sam Houston State University researcher Juan Daza and his from light green to colleagues identified this fossil, above,* from Myanmar, as a new gray or brown albie species that lived 99 million years ago. Writing in Science, Daza’s to match their team added to albies’ profile: Lizardlike, with scales and claws, likely rocky habitat—a living in or around trees, these sit-and-wait predators used their long, camouflaging more powerful tongues to nab small invertebrates. — D I N A F I N E M A RO N common in heav- ily picked areas. It PHOTOS: DAVID GRIMALDI (AMBER); KELLY BARNES, GETTY IMAGES (DOG); YANG NIU (PLANT, BOTH); seems this clever EDWARD STANLEY, FLORIDA MUSEUM OF NATURAL HISTORY (CT SCAN: SKULL) plant is evolving to be less visible to its primary predator: humans. —HICKS WOGAN

E X P L O R E | DECODER LIFE Black-backed woodpeckers are known as ecosystem AFTER engineers—and they prefer their forests burned. Each year FIRE these birds drill nesting cavities in fire-damaged forests, where they blend in well. They also dine on wood-boring Black fire beetles that thrive amid the ashes. Marvels of anatomy, beetle larva they can peck into some of the hardest trees thousands of times a day without sustaining concussions or other Three toes physical harm. B Y T A Y L O R M A G G I A C O M O They can lean back farther, and thus strike harder, Powerful beak Resilient bone than four-toed species. Chisel-like beaks The front of the skull is are covered in thick, spongy bone that tough keratin. acts as a shock absorber. Head protection A small, smooth, and dense brain rarely collides with the skull as the bird pecks. Extra eyelids Specialized third eyelids (nictitating membranes) keep out flying debris. Versatile tongue A long tongue and tongue bone can dislodge insects and decrease vibrations. Pecking muscles Exceptionally fast neck muscle contractions help with powerful pecking. Black fire beetle Black-backed Melanophila acuminata woodpecker (male) ACTUAL SIZE Infrared heat sensors 1 2 BEETLES SENSE HEAT Supporting tail feathers FEASTING Hours after fire Sturdy, stiff tail feathers Months after fire brace the bird as it perches Wood-boring fire beetles use against a tree. Woodpeckers hunt for wood-boring heat sensors to find burned beetle larvae, their main food source. trees miles away, where they The birds have usually colonized an lay their eggs. area by the first spring after a fire. 22 N AT I O N A L G E O G R A P H I C

ALASKA These woodpeckers thrive in forests that are “pyrodiverse,” a (U.S.) mosaic of areas burned at differing severities and juxtaposed with Black-backed CANADA unburned areas. As fires become woodpecker range UNITED STATES larger and more severe, these mosaics may be lost, diminishing (Picoides arcticus) habitat quality even for such a fire-loving species. Mountain Shared parenting bluebird Both sexes of the black-backed woodpecker incubate eggs insect consumer and tend their young. Northern flicker Myotis bat insect consumer insect consumer Flying squirrel Black-backed woodpecker seed and fungus (female) dispersal Squirrel seed dispersal Chickadee insect consumer Bumblebee Afterlife of the forest Once the birds leave, it can pollinator take decades or more to know if the forest will fully recover. Second homes Other habitat-restoring species live in former woodpecker nests. Chipmunk 4 seed dispersal MOVING AWAY 4-8 years 3 Black-backed woodpeckers leave HOMESTEADING for newly burned forests when Annually fire-killed trees deteriorate and They excavate cavities to make beetle populations diminish. new nests every year; chicks hatch in spring. Old nests shelter many small mammals and other birds. SOURCES: RODNEY B. SIEGEL, INSTITUTE FOR BIRD POPULATIONS; VICTORIA A. SAAB, FOREST SERVICE; DANIEL YOUNG 23 AND JACKI WHISENANT, UNIVERSITY OF WISCONSIN-MADISON; CORNELL LAB OF ORNITHOLOGY; EBIRD

E X P L O R E | BEING THERE ROCK STEADY Moab, Utah, draws ‘moon walkers,’ stargazers, and adventurers. GETTING THE SHOT NIGHT VISIONS DAYTIME MOVES This image of Andy Lewis With three designated Surrounded by public silhouetted against a full International Dark Sky lands featuring Jurassic- moon took four months Parks less than an hour’s era sand dunes weathered to make. “Even with every drive from Moab, those into titian-tinted cliffs piece of technology we who can’t see the Milky and spires, Moab lures could get our hands on, it Way from their homes adventurers and nature came down to going there, (a majority of Americans) lovers who want to scouting, and seeing what can get their star fix there. interact with the elements. lined up,” says photogra- At Arches and Canyon- Activities range from pher Renan Ozturk, who lands National Parks, and the mainstream (rafting, aimed his camera from at Dead Horse Point State biking, hiking) to the more than a mile away to Park, visitors can gaze extreme (slacklining, BASE frame the shot of Lewis up at thousands of stars jumping with parachutes on a slackline (a length of visible to the naked eye— or wingsuits). Parks in the woven fabric that’s sus- compared with the few area have also taken steps pended in the air). When dozen, at most, visible to make the outdoors the weather, people, from a big city. To help more accessible for people and moon did eventually maintain these stellar with disabilities. align, “we only had about views, Moab has strength- a 30-second window to ened its ordinances capture the moment.” against light pollution. 24 N AT I O N A L G E O G R A P H I C

‘THE MORE TIME YOU SPEND IN THESE DESERT CANYONS, THE MORE YOU FEEL THE PRESENCE OF THE ANCIENT PUEBLOANS.’ —Renan Ozturk BY THE NUMBERS 100 A P P ROX I M AT E L E N GT H , I N F E E T, OF THE SLACKLINE SHOWN HERE 300+ AGE OF OLDEST ROCK LAYERS, IN MILLIONS OF YEARS, IN CANYONLANDS NATIONAL PARK 2,000+ NUMBER OF ARCHES IN ARCHES NATIONAL PARK NORTH AMER. The moon sets behind the rim Moab, of a canyon in Utah Moab, Utah. PACIFIC M A R C H 2 0 2 1 25 OCEAN BY NORIE QUINTOS PHOTOGRAPH BY RENAN OZTURK NGM MAPS

E X P L O R E | DISCOVERY ADVENTURE AWAITS FROM LETHAL TR TO ARTFUL TREAS I AVA I L A B L E W H E R E V E R B O O K S A R E S O L D PHOTOGRAPHS BY ESTHER R T W I C E A M O N T H , conservation biologis several of his colleagues, along with sta Wildlife Authority, pile into four-wheel mission? To find and remove snares—w wildlife—in northwestern Uganda’s Mu Park. Recent research suggests poacher per square mile in this park than anywh Most poachers here target antelope, b meat, but elephants, giraffes, and other a into the traps. Villages north of the park Uganda, and many of the snares are set b seeking protein-rich sustenance. Since 2015 Mudumba, a National Geo has taken part in snare-removal operati co-founder of Snares to Wares. The non nity members to transform recovered sn sculptures of African wildlife. In additio artisans, the employees earn an income afford other types of food, as well as bas cine. “It’s about alternative food source [locals],” says Mudumba. The program e sans and typically sells more than 800 s mainly through gift shops in the United NatGeoBooks @NatGeoBooks © 2020 National Geographic Partners, LLC

E X P L O R E | ATLAS THREE GORGES DAM SNAGGING SNARES SETTING During one five-hour search, RIVERS FREE a team can collect about 200 traps, which local artisans B Y H E AT H E R GA BR IE L SM IT H A N D C H RI ST I N A S H I NTANI craft into sculptures of giraffes, hippos, and other wildlife L O N G, F R E E - F L OW I N G R I V E R S are over a thousand kilometers long (621 that populate the park. increasingly rare. These serpentine miles) still run free. Human impacts giants should support entire ecosystems include dams trapping sediment so RAP and allow the unobstructed movement that it can no longer naturally shape SURE of energy, materials, and wildlife in their the river and deltas, and regulation of waters and in the surrounding land- reservoir water levels to reduce flow to RUTH MBABAZI scape. But humans have been harness- a trickle in some areas. Just how much ing their immense power for centuries, these obstructions disrupt connectivity st Tutilo Mudumba and building so many dams and reservoirs, can vary throughout a river, but under- affers from the Uganda and so much other infrastructure, that standing their many consequences is -drive vehicles. Their now only 37 percent of the world’s rivers crucial to restoring these ecosystems. wire traps intended to kill urchison Falls National Yen rs set more illegal snares Ob here else in the world. Leeyna buffalo, or warthogs for is animals also stumble NORTH NileASIA A mu r AMERICA low are among the poorest in C by impoverished locals Mississippi Yel Yangtze THREE GORGES ographic explorer, Amazon DAM ions in the park as the nprofit engages commu- SOUTH AFRICA nares into intricate AMERICA on to learning skills as ongo e that allows them to ic needs such as medi- Free-flowing es but also empowering Human impacted employs some 600 arti- culptures each month, d States. —JA N I H A L L 28 N AT I O N A L G E O G R A P H I C

the water withdrawn. Bordered by small IRKUTSK XIANGJIABA uprooted more than N farming towns without a million people. large dams, the Amur— Lake Y E N I SSAYAN MOUNTAINS NILE Khabarovsk the least obstructed of Baikal SICHUAN these 10 rivers—is an Chongqing BASIN example of the effects of minimal human Yangtz influence. e BRATSK E White Nile Y Blue Nile UST-ILIMSK N Yenisey - THREE GORGES Yichang Angara A GEZHOU OCKY MOUNTAINS BOGUCHANY N MROBYRLAOANCK EAGLE Sea of The four dams G Okhotsk obstructing the JABAL R IrtyshNY Yenisey-Angara Wuhan AWLYA created one of Earth’s Khartoum CLARK SER B-IRTYSHri largest water-storage A CANYON O FORT PECK systems. Reservoir LIMA A construction has had R MEROWE Misso u KEKETUOHAI KALASUKE negative upstream A Nanjing effects on Lake Baikal. HAU PROJECT 635 Yenisey Wuhu LTAY MOUNTAINS Zhenjiang Lake Shanghai Zaysan Sea East China Nile BUQTYRMA uri OSKEMEN YELLO Lake GARRISON Qinghai Nasser SHULBINSK Lake isso ASWAN HIGH M Yellow ASWAN LOW OAHE Red NAJ HAMMADI BIG BEND NINA LAXIWA WN Sea ASYUT GREAT PLAINS GONGBOXIA LIUJIAXIA GAVINS POINT BAPANXIA Lanzhou TENGGER Nile Missouri Omsk The Yellow gets its DESERT name from its yellow- QINGTONGXIA Cairo Kara Sea brown color, caused by silt that leaves behind HAIBOWAN Mediterranean Sea Kansas City a yellow residue after The Mississippi has i flooding. The river is SANSHENGGONG M ississipp crucial for agriculture ORDOS long been an artery DESERT for trade, with major in this arid climate. engineering projects St. Louis - tysh controlling its flow for 300 years. Now I N Ir Flowing through a obstructions impair Ob series of hydropower connectivity on most stretches of the river. dams, these waters grew so polluted and New sediment-filled that the Orleans Ob-Irtysh in western and west-central Asia of Mexico is no longer a source of clean drinking water. TLIWAOANNNQGJIKIAAOOZUHsippiPSANMENXIA Gulf Missis P XIAOLANGDI AI I XIXIAYUAN SMeSmpIhiIsSSSSOI Zhengzhou N R Kaifeng I U Yellow Jinan Binzhou M M f Ob Ob Gulf o Bo Hai NOTE: DAMS ON THE UPPER YANGTZE WERE NOT INCLUDED IN THE ASSESSMENT. TED SICKLEY AND RYAN MORRIS, NGM STAFF. SOURCES: GÜNTHER GRILL AND BERNHARD LEHNER, NATURE, MAY 2019; WALTER IMMERZEEL

S PACIFIC OCEAN ANDES Chambeshi im Vit MOUNTAINS antaro Luapula TANOVOY Le M Lake LENA Ucayali Marañón Luvua Mweru L ualaba na AM Lake A Tanganyika FREE OR MANAGED ZON N CONGO JIN N The 10 longest rivers on Earth range from N CENTRAL free-flowing to having Kisangani YAKUTSK good connectivity to being Yakutsk LOWLANDS severely affected by dams Flowing through nine or other human influences. countries, the Congo Lena RANGE The landscape through has some of the deepest which a river flows is stretches of any river. another factor that can frag- Remoteness and ment or stress the waterway. conflict discouraged VERKHOYANSK Her zon development, leaving the Ama river still mostly wild. N A long, free- Imp RI V E R SYSTE M The Amazon flows flowing river, the a cted Good conne from the Andes to the Lena discharges Atlantic Ocean. The Congo Kinshasa world’s longest free- into the Arctic DAM v ity A mazonree-flowing flowing river also Brazzaville Ocean. Its delta Citycti releases the most water, F about 20 percent of supports an total global discharge. ecologically vital Manaus wetland system ARCTIC OCEAN OATCLEAANNTIC that’s a refuge for Siberian wildlife. len igaliK AM U Lake Kager a Z E Victoria Lake Argun Edward N GT OWEN Lake R ATLANTIC OCEAN Y A Jinsha FALLS Albert N Selenga Lake RKUTSK Kyoga LONGKAIKOU LIYUAN The Yangtze flows through sprawling cities The world’s longest LUDILA ANAQHIAAIO and diverse habitats river, the Nile, is the GUANYINYAN where snow leopards most affected by water and giant pandas live. use among these giant Heihe The construction of rivers. Irrigation and the Three Gorges Dam other human use Amur XILUODU threatened wildlife and account for the bulk of

E X P L O R E | CLOSER LOOK Hidden Narratives B Y J E N N I F E R B A R G E R A N D H E AT H E R G R E E N WO O D DAV I S O O N H E R DAYS O F F, New Yorker Cheyney McKnight might pull on leggings and a T-shirt or an AT LIVING HISTORY SITES, African-print dress. But it takes a bit longer for her PEOPLE OF COLOR PORTRAY to get ready for her day job, when she dresses in a chemise, a corset, and three layers of petticoats FIGURES FROM THE PAST, topped by a cotton gown and a fabric head wrap. REVISITING PAINFUL ISSUES AND SHARING THEIR SIDES McKnight is a 21st-century Black American, but the historical interpreter and founder of Not Your OF THE AMERICAN STORY. Momma’s History specializes in portraying enslaved and free people during the 18th and 19th centuries 32 N AT I O N A L G E O G R A P H I C in the United States. Drawing on almost a decade of work at living history sites including Virginia’s Colo- nial Williamsburg, she might dress as an enslaved person to demonstrate hearth cooking at a Virginia plantation or depict a free Creole woman during a New Orleans history festival. McKnight, like many interpreters, works in the third person, mimicking the garb of the past but not pretending to be a character from another time. She thinks this perspective allows her to speak more plainly and to put difficult issues like enslavement, racism, and torture into context. “It can be difficult interacting with guests, but I want to meet the challenge,” says McKnight. “My goal is to increase accurate portrayals of Black Americans at historic sites and museums.” In the U.S. most historical interpreters work at one of the nearly 200 living history museums across the country, from immersive places like Colonial Williamsburg to smaller sites, such as Civil War forts or grand Victorian-era estates. Some historical interpreters are full-time employees, others part-timers or volunteers at spe- cial events. They do everything from conjuring well- heeled 1930s party guests on tours of California’s

PHOTO: JARED SOARES Adam Canaday, a journeyman coach driver at Colonial Williamsburg, stands next to his horse, Commodore. Canaday is one of the dozens of historical interpreters of color who work at the living history site in Virginia. M A R C H 2 0 2 1 33

E X P L O R E | CLOSER LOOK Hearst Castle to marching as 1880s soldiers at Mich- American Revolution spy James Armistead Lafayette. igan’s Fort Mackinac. Historian and actress Mary Carter began portray- These time-traveling guides and sites share a mis- ing Aggy, a real-life 18th-century enslaved Black sion to educate visitors about history by immersing woman, at Colonial Williamsburg in 2011, drawn by them in people, places, and activities. But institutions her unexpectedly nuanced biography. Like many that employ—and try to honestly depict—Black, enslaved women, Aggy was impregnated by the Indigenous, and other people of color still have a plantation owner, Ryland Randolph, and bore him long way to go. two children. More unusual: When Randolph died, his will stipulated that Aggy and her children be In the early 20th century, many historical sites freed. It would take a battle in courts to enforce his glossed over people of color or simply left them out wishes. “I wanted people to know her name and to of their programming. Plantations might have had a know her story,” says Carter. costumed guide, but it was probably a white woman decked out as a Gone With the Wind–style lady of the In tours and talks, Carter veers into disturbing manor. If the enslavement of people was alluded to, topics like consent, violence, and human rights. staffers might genteelly mention “servants.” As Aggy, Carter is wary and speaks with hesi- tation, conveying the cornered nervousness of In the late 18th century, about half of the popula- someone whose time, words, and movements are tion of the city of Williamsburg was Black, burdened not her own. The questions visitors pepper her with the firewood chopping, bedpan emptying, and with—“Did Randolph love her? Was he good to farming that kept the capital of the colony of Virginia her?”—demand hard-to-hear answers. “I under- humming. Colonial Williamsburg, a 301-acre open- stand what they’re asking: They want to know if air museum of early American life, was built in 1932 there was hope or a silver lining,” says Carter. on the remnants of the old city. But in its early days, “I think enslaved people did find moments of joy, but only a few costumed employees represented Black it’s wrong to look for them in the actions of people citizens, most of them dressed as coachmen. who held them in bondage.” When first-person interpretation started at Colonial Like most interpreters, Carter continues her Williamsburg in the late 1970s, three Black actors were research—through letters, court documents, and among the troupe of nine people. They portrayed a diaries. Her portrayal of Aggy is ever evolving. “There range of enslaved characters, including the Reverend have been times in my own life I was made to feel Gowan Pamphlet, a minister who was eventually freed. ashamed because I was a descendant of enslaved Today 36 first-person actor-interpreters are on staff; people,” she says. “But they forgot to tell me to be 15 are Black, though the total number of costumed proud of what they endured, what they survived, interpreters of color on site is just 14 percent. what their strength caused them to push through.” j “We still haven’t found the sweet spot to make sure Jennifer Barger is a senior editor and Heather Greenwood that the full story is told, but we’re further than we’ve Davis a contributing editor at National Geographic. ever been,” says Stephen Seals, who plays enslaved Tourists walk down Duke of Gloucester Street, the main road at Colonial Williamsburg, which closed briefly last year because of the pandemic. More than 600 original and reproduced structures evoke the onetime capital of the Virginia colony. PHOTO: JARED SOARES

Now Streaming © 2021 Disney and its related entities.

I UNLOCK THE SECRETS OF THE COSMOS NEIL DEGRASSE TYSON, a renowned physicist and science popularizer, is taking on the big questions that humanity has been posing for millennia— How did life begin? What is our place in the universe? Are we alone?— with wit, wisdom, and cutting-edge science. This relatable and entertaining book will engage and inspire readers of all ages, bring sophisticated concepts within reach, and offer a window into the complexities of the cosmos. COMING SPRING 2021. © 2021 National Geographic Partners, LLC P R E - O R D E R YO U R C O P Y TO DAY.

NATIONAL GEOGRAPHIC MARCH 2021 F EAT U R E S Fascinating Mars ......... P. 38 Off Death Row . . . . . . . . . . . . P. 66 The Battles for the Siachen Glacier . . . . . . . . . . . P. 94 Dog Racing Decline ... P. 122 94 ‘FOR DECADES, INDIA AND PAKISTAN HAVE SENT YOUNG SOLDIERS TO THIS HARSH ENVIRONMENT, WHERE THEY REMAIN FOR MONTHS AT A TIME, GUARDING A REMOTE, UNINHABITED WILDERNESS.’ PHOTO: CORY RICHARDS

BY NADIA DRAKE PHOTOGRAPHS BY CRAIG CUTLER AND SPENCER LOWELL Our Obsession With MARS THE DUSTY RED PLANET HAS FASCINATED US FOR CENTURIES. EVEN AS WE LEARN MORE, ITS MYSTERIES KEEP US IN SUSPENSE. Then and Now civilizations never flourished there, rovers Early, blurry views of such as Curiosity (right) Mars inspired stories now drive the search of canal-building for microbial Martians. aliens. While intelligent 38 PERCIVAL LOWELL, LOWELL OBSERVATORY ARCHIVES (ABOVE); MOSAIC OF 57 IMAGES BY NASA/JPL/MICHAEL RAVINE, MALIN SPACE SCIENCE SYSTEMS



Assembling Mastcam-Z Flight assembly tech- nician Olawale Oluwo of Malin Space Science Systems in San Diego, California, holds part of Mastcam-Z, a pair of cameras with zoom capabilities installed on NASA’s Perseverance rover. A Mastcam-Z camera is tested in a chamber (right) that simulates the planet’s wide swings in surface temperature. CRAIG CUTLER (BOTH)



Eight spacecraft are operating in orbit around Mars or exploring its dusty surface. In February 2021, as of press time, three more robotic emissaries are scheduled to rendezvous with the red planet, including the flagship NASA rover, Perseverance. A Clean Start Engineers at NASA’s Jet Propulsion Laboratory in Pasadena, California, work in a sterile room to calibrate the Perseverance rover’s 23 cameras before launch. Given the rover’s goal of looking for signs of life on Mars, technicians took many precautions to avoid contaminating the machine with Earth-based microbes. SPENCER LOWELL



I It’s a warm night in mid-October, and I’m winding my way up to the University of Virginia’s McCormick Observatory on a quest to solve an abiding mystery: Why are Earthlings so dang obsessed with Mars? The observatory’s hilltop dome is open, etching a glowing amber crescent into the autumn darkness. Inside stands a telescope that will help me see Mars as it appeared to observers more than a century ago, when eager astronomers used this instrument in 1877 to confirm the dis- covery of the two tiny Martian moons, Phobos and Deimos. Tonight UVA astronomer Ed Murphy has made a special trip up to the observatory, which is closed to the public because of the ongoing coronavirus pandemic. The whirling dance of orbital dynamics has put Mars at its biggest and brightest in the sky right now, and Murphy cal- culated that this would be the best time to see it from central Virginia, where the turbulent air can sometimes complicate nighttime sky-gazing. He climbs up a ladder and settles onto the view- ing platform, a wooden perch constructed in 1885, 44 N AT I O N A L G E O G R A P H I C SPENCER LOWELL (RIGHT)

Visionary Technology The twin boxes seen above on Persever- ance’s mast are its main cameras, which stand six and a half feet off the ground and are positioned to enable stereo vision. The views of Mars they send back will “make us feel like we’re standing there,” says planetary scientist Jim Bell of Arizona State Univer- sity. Unlike the human eye, these instruments can “see” in multiple wavelengths.

Rolling in interest in Mars is ageless. For millennia we’ve the Deep made sense of Mars by attaching our deities to Getting a spacecraft it, charting its motion, and mapping its face. to Mars is not easy, We’ve worked Mars into our art, our songs, our and many early missions literature, our cinema. Since the beginning of failed. But in 1997 NASA’s the space age, we’ve also hurled more than 50 Pathfinder mission pieces of hardware—engineering marvels that successfully landed collectively cost billions of dollars—at Mars. and released Sojourner, Many, especially early on, have failed. And still the first wheeled rover our Mars mania marches on. on the planet. This pioneering robot has As I meet with Murphy in October, eight a supporting role in the spacecraft are operating in orbit around Mars 2015 film The Martian. or exploring its dusty surface. In February 2021, as of press time, three more robotic emissaries NASA/JPL are scheduled to rendezvous with the red planet, including a flagship life-seeking NASA rover and nudges the giant telescope toward the con- called Perseverance and two potentially history- spicuous orange dot of light. He fiddles with a making missions from China and the United knob, bringing the planet into focus. “Wait for Arab Emirates. those few moments when the atmosphere settles down, and you’ll actually see Mars looking crisp But, why? Among the worlds we know, Mars is and clear … and then it will all get blurry again,” not superlative in any way. It’s not the brightest, he says through his space-themed face mask. the closest, the smallest, or even the easiest to get to. It’s not as mysterious as Venus; not as spectac- We swap places. Through the telescope, Mars is ularly adorned as jewel-toned Jupiter or ringed an upside-down, peach-pink sphere that swims Saturn. It’s arguably not even the most likely in and out of resolution. I hesitantly sketch its place to find extraterrestrial life—that would be shadowy features during fleeting moments the icy ocean moons of the outer solar system. of clarity, doing my best to channel the 19th- century scholars who once charted its landscapes, “A bunch of red dirt on Mars is not as inter- some fervently believing that its alien face bore esting as some of these other worlds,” says Paul the markings of an advanced civilization. Byrne, a planetary scientist at North Carolina State University. “I don’t advocate for a second Today we know there are no immense engi- that we shouldn’t be exploring it. I do advocate, neering scars crisscrossing the planet’s vermilion loudly, that we should be considering how Mars surface. But that doesn’t really matter. Human fits into the overall space exploration strategy.” The scientific reasons why Mars is a compel- ling target are complex and evolving, propelled by a cornucopia of images and information from all those orbiters, landers, and rovers. Mars is a perpetual enigma, a place we’re always on the cusp of knowing but don’t truly understand. “This is one of the world’s longest unfolding discoveries,” says Kathryn Denning, a York Uni- versity anthropologist specializing in the human elements of space exploration. “It’s this giant exercise in suspense.” And the reason Mars remains lodged in the popular zeitgeist might be witheringly simple: Even as our picture of it has sharpened over time, we can still easily envision ourselves there, building a new home beyond the confines of Earth. “It’s just blank enough,” Denning says. With a sloppy sketch of Mars in my hand, I think of the decades we’ve spent chasing little 46 N AT I O N A L G E O G R A P H I C

green men, and microbes, and human settle- The View ments, and how Mars fervor has returned after From Above every setback. At the same time, I know plenty of Pictures from NASA’s scientists are ready to heap our dreams—and our Mars rovers not only robots—onto other inviting destinations across advance science, they the solar system. As scientists juggle limited also can endear the resources and increasing competition, I can’t robots to the public. help but wonder if we’ll ever shake ourselves In 2014 the Opportu- loose from the allure of Mars. nity rover sent back this selfie, made of multi- S I N C E C I V I L I Z AT I O N S first gazed skyward, ple combined images. humans have followed Mars and charted its It showed the rover’s capricious path through the heavens. As the solar panels coated with Sumerians tracked this “wandering star” cross- sun-blocking dust. ing the sky in the third millennium B.C.E., they noted its foreboding color and associated it with MOSAIC IMAGE BY NASA/JPL/CORNELL UNIVERSITY/ARIZONA STATE UNIVERSITY the malevolent deity Nergal, god of pestilence and war. Its movements and varying brightness detail, and instead of conforming to contempo- portended the deaths of kings and horses or the rary naming conventions, he labeled the exotic fates of crops and battles. features on his version of the planet after places in Mediterranean mythologies. Aboriginal cultures also note its color, describ- ing it as something that has been burned in “That was a really massively bold statement to flames or linking it to Kogolongo, the native make,” says Maria Lane, a historical geographer red-tailed black cockatoo. The pre-Columbian at the University of New Mexico. “It’s basically Maya carefully plotted the object’s position rela- him saying, I saw so much stuff that was so dif- tive to the stars, tying its movements to shifting ferent from what anyone else had seen, I can’t terrestrial seasons. The Greeks associated it with even use the same names.” Ares, after their god of war, whom the Romans recast as Mars. As a result, Lane says, Schiaparelli’s map was instantly authoritative. Scientific and popular “There was always only one actual planet opinion pronounced it a powerful representation Mars, but there are a lot of different cultural of truth. Three decades of unconstrained Mars Marses in play,” Denning says. mania followed, and by the end, any reasonable person would be forgiven for believing intelligent By the mid-1800s, telescopes had trans- Martians had built a planet-spanning network formed Mars from a mythological figure into of canals. Much of that Continued on page 56 a world. As it came into focus, Mars became a planet with weather, shifting terrains, and ice caps like Earth’s. “The very first time we had a way to look at Mars through the eyepiece, we started discovering things that were chang- ing,” says the SETI Institute’s Nathalie Cabrol, who has studied Mars for decades. With more advanced instruments, this dynamic place could be studied—and mapped. During the Victorian era, astronomers sketched the Martian surface and presented their drawings as fact, although the whims and biases of the mapmakers influenced their final products. In 1877 one of those maps captured international attention. As drawn by the Italian astronomer Giovanni Schiaparelli, Mars had harshly delineated topography, with islands that erupted from dozens of canals, which he colored blue. Schiaparelli stuffed his map with O U R O B S E S S I O N W I T H M A R S 47

SCIENCE PERSEVERES A CLEAR VIEW Mastcam-Z assesses Mars’s The COVID-19 pandemic hit as NASA scientists and engineers geology and atmosphere. were readying their newest Mars rover for liftoff. The aptly The Navcams allow the rover named Perseverance conquered its first challenge by to be directed from Earth. launching last July, on target for landing in February 2021. The rover’s mission was planned for at least one Martian SuperCam year—or 687 days, as humans calculate time on Earth. Navcams FAR-FLUNG LAB Mastcam-Z Sampling Big daily temperature swings and rocky arm, stowed terrain make for tough working conditions. Caching To survive, this rover’s body is based on past system vehicles but with newly designed wheels, more brainpower, and a stronger arm. MOXIE: The Oxygenator MEDA atmospheric Future human visits might be possible analyzer if this technology test can produce oxygen molecules from Mars’s carbon dioxide-rich atmosphere. Intake Separation Result CO2 by heat and O2 electricity RIMFAX MOXIE CO Exhaust RIMFAX: The Revealer 43 sample Radar waves reaching tubes 30 feet deep will reveal what’s under the surface; Storage 3D modeling will help The arm transfers the identify intriguing finds, sample tubes into the such as ice or water. rover’s body through a carousel. Once inside, the RETRIEVE 7 feet tubes are checked, sealed, AND RETURN and moved into storage. Rolling along at a top speed Collected samples will of 0.1 miles an hour, the 2,260- be deposited at a well- pound rover will collect rocky documented site on samples from Jezero crater the surface to await for eventual return to secure retrieval years later. laboratories on Earth. DEPOSIT COLLECT 2021-2023 MANUEL CANALES, NGM STAFF; PATRICIA HEALY. ART: BRUCE MORSER. SOURCES: NASA/JPL; NASA

Solar panel Carbon-fiber EARTH blades TEST FLIGHT Earth Entry Vehicle Ingenuity, a small helicopter, will test 2031 if vehicles can fly in Ingenuity Mars’s thin atmosphere. DATA LASER SAMPLE TUBE The return capsule RETURN BEAM ACTUAL SIZE will detach from the orbiter to enter Laser scan Earth’s atmosphere. SuperCam’s lasers vaporize rock and Earth reflect back information Return about its composition Orbiter and chemical makeup. SAMPLING ARM SHERLOC: The Prospector Sample Magnifying cameras return A heavy rotating turret on a and lasers detect and map capsule flexible, seven-foot-long arm minerals that might be holds instruments to analyze useful samples to collect. rocks for traces of past life and a drill to collect samples. WATSON magnifying camera PIXL Drill SHERLOC X-ray UV laser Mars beam scanner Ascent Vehicle PIXL: The Detector Rock sample The rocket settles Working in the dark into low orbit and of night, x-ray fluo- Coring drill releases the sample rescence can pick up Cylinders of solid rock container to the the chemical traces and surface material are Earth Return Orbiter of potential fossils. collected in sterile tubes. for the trip home. Sample Sample Tube Return Lander Sample Fetch Rover RETRIEVE The European Space Agen- An arm on the lander cy’s solar-powered Sample will transfer the tubes Fetch Rover will collect into a container that will the filled tubes and drive be rocketed into orbit on them to a NASA lander. the Mars Ascent Vehicle. RE-COLLECT 2028

-2100 -2200 M -2300 -2300 R-2000 ne -2100 I -1900 -2200 -1,743 m s t l i -1800 -2200 t co a -2200 -1900 -2100 -2000 c i e n -2400 C A n R -2200 -2100 AT E R R E a -2100 Z Neretv -2200 E -2300 J V a li s -2400 -2400 D e l t a fa l -2300 -2200 -2100 -2300 Belva crater -2000 -2200-2000 -2100 deposit RIM -1900 -2500 -1800 -1900 -1800 C RAT -1800 -1,650 mE -1700 R Perseverance land

LAKES OF A BYGONE ERA -2500 -2500 SIGNATURE OF FLOW Geologists are looking for tell- tale patterns that ancient bod- Ancient river deltas on Mars formed much as they do on ies of water leave on rocks and Earth. Fast-flowing water meets standing water, depositing minerals. Erosion at the edges bits of sand, minerals, and silt eroded from the surrounding of a lake leaves beach sands valley. Scientists hope sediments collected from Jezero and wave-cut terraces, while crater might hold traces of life that washed into the basin. certain clays and hydrated min- erals can form or be deposited only in the presence of water. -2500 COSMIC Crater rim COLLISION Impact crater CRATER O A meteorite formed the 28-mile-wide Jezero crater some four billion years ago. Over time, the crater filled with volcanic debris. -2500 WATER FILLS Valley Perseverance landing zone THE CRATER incision Roughly half a billion -2500 years later, during Water Mars’s wet era, two an MOVING UP THE DELTA flowing channels broke Perseverance will use its through the crater’s suite of scientific instruments rim, creating a lake to plumb the mysteries inside the basin. of how the delta formed at at Jezero crater and to see MINERALS whether fossilized microbes ACCUMULATE might be trapped in its Moving water contin- layers of sediments. ued to deposit mate- rials at the basin’s edge, forming a delta lined with sediments washed in from afar. s -2600 MARS DRIES UP Ancient coastline Liquid water and much HEADED FOR THE PLAINS of the ice disappeared Delta Landing Slated to land on the flat from the red planet 3.5 zone surface of the crater floor, billion years ago, leaving Perseverance eventually will behind a dried lake bed climb up the channels of the at Jezero. The remaining delta into the river valley— delta has shrunk over then on to the plains beyond. time from wind erosion. -2600 MATTHEW W. CHWASTYK AND MANUEL CANALES, NGM STAFF ALEXANDER STEGMAIER. CRATER TIME LINE ART: MATTHEW TWOMBLY ding zone Contour interval: 10 meters SOURCES: USGS ASTROGEOLOGY RESEARCH CENTER; NASA; TIMOTHY A. GOUDGE, 1 mi UNIVERSITY OF TEXAS AT AUSTIN; BRIONY HORGAN, PURDUE UNIVERSITY 1 km * WITH THE ABSENCE OF SEA LEVEL, HEIGHTS ON MARS ARE CALIBRATED TO THE ALTITUDE WHERE WATER COULD EXIST AS LIQUID, A SOLID, OR A GAS. Elevations are referenced to a THIS ELEVATION ON THE PLANET’S SURFACE IS DESIGNATED AS ZERO AND 3,390-kilometer-radius sphere.* PLACES THAT ARE LOWER ARE EXPRESSED AS NEGATIVE NUMBERS.

IMPRINTS OF A WATERY PAST Early visions of alien-made canals turned out to be fantasy, but Mars does boast geologic features such as river channels and deltas that hint at a wet history. Now, after more than 40 years of exploration, scientists have a deeper understanding of the planet’s surface—and how parts of the landscape were transformed by flowing water some three and a half billion years ago. Jezero Drainage 300° System LunaeEQUATOR X A N T HE Planum Ancient ocean T E R RA This map stretches Inlet ENLARGED 330° Viking 1 240° Mars’s northern and valley AT LEFT 270° southern hemispheres (U.S.) Landed at the equator to show JEZERO Outflow the whole planet and Inlet valley CRATER valley July 20, 1976 its wet and dry areas Mars in proper proportion. Ancient lake Pathfinder TEMPE 30°N (U.S.) Landed July 4, 1997 T E R R A Perseverance A ci dal ia a Possible extent landing zone P lan iti of ancient ocean 25 mi 0°ARABIA TERRA A 60° I T A S Phoenix 25 km V ST (U.S.) Landed WARM AND WET Warmer weather, closer to Earth’s average of 57 ̊ F, North Pole May 25, 2008 would have allowed for running water and even rain. Storms might have cleared the air of most dust a Olympus to create bluer skies. The wet and rocky Martian Mons landscape could not have supported vegetation. B O R E A LIS cadi COLD AND ICY itia Temperatures colder than Antarctica would have kept any surface water frozen, with ice and snow 60° Viking 2 Ar at high elevations. Volcanic lava and steam might (U.S.) Landed an have briefly warmed some regions. Ancient Mars would have appeared more gray; today oxidized l iron gives its soil a ruddy hue. P Sept. 3, 1976 Planitmiaazonis Utopia Planitia 30° ENLARGED A 210° ABOVE TERRA Beagle 2 30°N Mars Science (U.K.) Landed, contact lost Laboratory–Curiosity Syrtis Isidis Dec. 25, 2003 (U.S.) Landed Major 60° Planum Planitia Mars InSight Aug. 6, 2012 90° (U.S.) Landed E l y s i um Nov. 26, 2018 150° P l a n 180° EQUATOR 0° it ia E T Y R R H E N A Hesperia Mars Exploration S SABA Rover-A, Spirit IR A ENUM TERRA Planum (U.S.) Landed 30° 30°S Jan. 4, 2004 0° Eridania Mars Exploration NOACHIS HeMN(llUaoas.vrSPs..Sl22a.n7R,it.1)ia9C7r1ashePdROMETPHlaE6nI 0Tit°EiRaRATERRA CIMMERIA 210° Mars 3 Rover-B, Opportunity Deep Space 2 Probes A (U.S.S.R.) (U.S.) Landed (U.S.) Crashed Landed, Jan. 25, 2004 Dec. 3, 1999 R contact lost ExoMars Schiaparelli Dec. 2, 1971 R (ESA) Crashed Australe T E Planum Oct. 19, 2016 South Pole Planum Mars Polar Lander (U.S.) Crashed Dec. 3, 1999 Daedalia R AON IA 240° E T 60° R A R Argyre T E R A Planitia Mars Mars 6 surface missions (U.S.S.R.) Crashed num Successful rover Mar. 12, 1974 Solis Pla MA3R30GT°EARRRITVAIFAELRL E S 30°S Other M A R I N E R I S 270° Ancient lake EQUATOR 300° TRANSVERSE MOLLWEIDE PROJECTION

ANCIENT HORIZONS In 2003 a rover found evidence that water once flowed on Mars, but early climatic conditions on the red planet are still up for debate. Models suggest two extremes that would have allowed some liquid to exist on the surface, illustrated here; scientists suspect Mars may have cycled between both states. MANUEL CANALES AND MATTHEW W. CHWASTYK, NGM STAFF; ALEXANDER STEGMAIER. ART: ANTOINE COLLIGNON SOURCES: ASHLEY PALUMBO, BROWN UNIVERSITY; ROBIN WORDSWORTH, HARVARD UNIVERSITY; NASA

Continued from page 47 fervor can be linked directly to Percival Lowell, a quirky aristocrat with a serious Mars obsession. A W E A LT H Y B O STO N I A N and Harvard University CRAIG CUTLER alum, Lowell had more than a passing interest in astronomy, and he was an avid reader of sci- that seasonally, the Martian polar caps shrank entific and popular texts. Inspired in part by and expanded, unleashing a swath of darkness Schiaparelli’s maps, and believing that alien that crawled toward the equator. Some scientists technology had crafted the Martian canals, Low- in the 1950s thought those shadowy areas had ell raced to build a hilltop observatory before the to be vegetation that flourished and died back, autumn of 1894, when Mars would make a close theories that made it into top-tier journals. All approach to Earth and its fully sunlit face would this scientific fervor fueled a trove of speculative be prime for observing those supposed canals. fiction, from H.G. Wells’s War of the Worlds and Edgar Rice Burroughs’s Barsoom serials to Ray With the help of some friends and his family Bradbury’s Martian Chronicles. fortune, the Lowell Observatory emerged that year near Flagstaff, Arizona, on a steep bluff that “In the days before we’d really explored Mars, the locals named Mars Hill. From there, among pre-1960s, there was just a wealth of imagina- the conifers, he dutifully studied the red planet, tion,” says Andy Weir, author of The Martian. waiting night after night for the shimmering “A science fiction author could say, I don’t know world to come into focus. Based on his obser- anything about Mars, so I can say whatever I vations and sketches, Lowell not only thought he want about Mars.” could confirm Schiaparelli’s maps, he believed he spotted an additional 116 canals. “The more Then, in 1965, NASA’s Mariner 4 probe swept you look through the eyepiece, the more you’re going to start seeing straight lines,” Cabrol says. “Because this is what the human brain does.” In Lowell’s estimation, the Martian canal builders were supremely intelligent beings capable of planetary-scale engineering—an alien race intent on surviving a devastating change in climate that forced them to build mammoth irrigation canals stretching from the poles to the equator. Lowell published his observations prodigiously, and his conviction was infectious. Even Nikola Tesla, the electric pioneer who famously sparred with rival inventor Thomas Edison, got caught up in the moment and reported detecting radio signals coming from Mars in the early 1900s. But Lowell’s story began to fall apart in 1907, in part because of a project he funded. That year, astronomers took thousands of photos of Mars through a telescope and shared them with the world. Planetary photography eventually replaced cartography as “truth,” Lane says. Once people could see for themselves how the photos and maps of Mars didn’t match, they no longer bought into the authority of Lowell’s maps. Still, by the turn of the 20th century, Mars had become a familiar neighbor with changing landscapes and the lingering promise of inhab- itants. The next wave of observations revealed 56 N AT I O N A L G E O G R A P H I C