Copyright © 2020 by Sarah Stewart Johnson
All rights reserved.
Published in the United States by Crown, an imprint of Random House, a division of Penguin Random House LLC, New York.
CROWN and the Crown colophon are registered trademarks of Penguin Random House LLC.
Title-page image: NASA/JPL-Caltech/Arizona State University
Part-title image: Illustration from Scientific American, August 20, 1892, “Professor Pickering’s Observation of Mars”
Chapter-opening image: Morphart Creation/Shutterstock
LIBRARY OF CONGRESS CATALOGING-IN-PUBLICATION DATA
Names: Johnson, Sarah Stewart, author.
Title: The sirens of Mars / Sarah Stewart Johnson.
Description: New York : Crown [2020] | Includes bibliographical references and index.
Identifiers: LCCN 2020007280 (print) | LCCN 2020007281 (ebook) | ISBN 9781101904817 (hardcover) | ISBN 9781101904824 (ebook)
Subjects: LCSH: Life on other planets. | Mars (Planet)
Classification: LCC QB641 .J64 2020 (print) | LCC QB641 (ebook) | DDC 576.8/39099923—dc23
LC record available at https://lccn.loc.gov/2020007280
LC ebook record available at https://lccn.loc.gov/2020007281
Ebook ISBN 9781101904824
randomhousebooks.com
Cover design: Elena Giavaldi
Cover images: Sand dunes lie next to a hill within an unnamed crater in eastern Arabia on Mars. This false-color mosaic, in which bluish tints indicate fine sand and reddish tints indicate outcrops of rock, was made from images taken at visible and infrared wavelengths by the Thermal Emission Imaging System on NASA’s 2001 Mars Odyssey mission. (NASA/JPL-Caltech/ASU); Fol 36-37 “Astronomia nova Aitiologetos,” by Johannes Kepler (engraving), Bridgeman Images (top right); August 20, 1982, “Professor Pickering’s Observation of Mars,” Scientific American (center left); Morphart Creation/Shutterstock (bottom right)
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Contents
Cover
Title Page
Copyright
Prologue
Part 1: A Point Is That Which Has No Part.
Chapter 1: Into the Silent Sea
Chapter 2: The Light That Shifts
Chapter 3: Red Smoke
Part 2: A Line Is Breadthless Length.
Chapter 4: The Gates of the Wonder World
Chapter 5: Stone from the Sky
Chapter 6: Traversing
Chapter 7: Periapsis
Chapter 8: The Acid Flats
Part 3: A Boundary Is That Which Is an Extremity of Anything.
Chapter 9: In Aeternum
Chapter 10: Sweet Water
Chapter 11: Form from a Formless Thing
Dedication
Acknowledgments
Notes
About the Author
Reading Group Guide
EVEN WITH THE miracle of modern travel, it takes days for me to reach the edge of the Nullarbor Plain: three or four flights, a quick shower in Perth, then a night or two backtracking east in a rented truck. The two-lane carriageway stretches endlessly through the ghost towns of Australia’s old goldfields. Eventually I turn onto dirt roads, onto red rock. When I stop the truck and climb down from the cab, everything is still. Finally, I’ve arrived at the place where the desert cracks open.
I come here every couple of years, to the ancient terrain of the Yilgarn Craton, some of our world’s oldest rocks. Dotted throughout the dark ochre expanse are oval ponds that are as corrosive as battery acid. Yet in these sulfuric waters, against all odds, is the most astonishing array of life. I come to investigate how primitive microbes survive the harsh conditions, how they harvest energy, and what traces they leave behind in the minerals. I come because I’m a planetary scientist and because this is one of the most similar places on Earth to the ancient surface of Mars. I come to the Yilgarn and other wild wastelands—like the McMurdo Dry Valleys in Antarctica, like the Atacama in Chile—to hone my skills at finding life.
Out in the desert, I rise with the dawn. I pull on my tattered field clothes and slather sunscreen across my face. My boots crack with salt as I slip my feet into them. I throw on my hat, with wine corks hung from string around its brim, ready to drive away the flies. I weigh my pack down with equipment and water and head straight onto the flats. I spend my days wading into the sucking mud. In some places the ground parts easily. In others, the enveloping salts are as hard as ice. I note the GPS coordinates, map the terrain, measure the water chemistry, and assess the minerals. Later, back in my laboratory, I will examine each tiny piece of the acid-encrusted world I place into a vial. The sun beats down. The wind whips around me. But I rarely notice. I’m focused, consumed.
At the end of my workdays, after I load up my instruments, I climb up on top of the dusty cab, exhausted. As the sun begins to set, and the sky turns salmon pink, and red dust hangs in the air, it’s not hard to imagine that I’m on another planet altogether. Staring off into the silence, I think of all my predecessors, some sitting in deserts just like this, some hoping to signal Mars with giant trenches of fire, others building enormous telescopes in the stock-still air. A boy curled up in the shadow of a Benedictine abbey, longing for his own corner of the unknown to map. A shutterbug from Indiana who developed tens of thousands of blurry images of Mars, hoping one might show something. A French aeronaut who piloted a helium balloon high into the stratosphere, so high that he might asphyxiate, just to get his measurements.
It’s a peculiar band I’ve joined, this pack of Mars scientists, fiercely bound across the generations by the enigma of a neighboring world. One might fairly wonder why we have pinned our hopes for finding life to this red planet. For the last couple of billion years, there has been no rain there. There are no rivers, no lakes, no oceans. Without the driving force of fluid erosion, scars left over millions of years by meteorites are strewn across the surface. Mars has no plate tectonics, no magnetic field, and little protective atmosphere. The terrain is quiet, exposed, and bewilderingly empty.
Yet long ago, before it rusted over, Mars was much more like Earth: smaller, but similar in size and elemental composition. In its early days, Mars was black with igneous rock. Untold piles of lava built the planet’s massive volcanic provinces, which bulged with enough basalt to flex the crust. The planet’s swollen side cracked opened as Mars cooled, with a fissure so deep that the Grand Canyon could disappear into a side channel. One of the largest mountains in the solar system was formed, towering over an escarpment that itself is nearly as tall as Everest.
Those volcanoes lifted greenhouse gases into the air, wrapping the surface with a blanket of atmosphere. We know from the geologic record that the terrain was warm and wet, at least periodically. Around the time life may have been getting started here—conceivably in volcanic pools, in Darwin’s “warm little ponds”—water was present on Mars, pregnant with possibility. In fact, there may have been enough water to fill a northern ocean, still and deep, with a seafloor as smooth and flat as the abyssal plains of the great Pacific.
Then, between three and a half and four billion years ago, our planetary paths diverged, and Mars was laid bare. Almost all of the atmosphere disappeared, and so did the water. The planet slipped into a deep freeze, colder than the cold of Antarctica, leaving Mars the hyper-arid, frozen desert we know today, bathed in high-energy solar and cosmic radiation. Now a dust the consistency of red flour coats the surf
ace, lofted by dust devils into the impossibly thin air.
Yet life, we have learned, is stunningly resilient. It can adapt, it can wedge into a crevasse, it can hang on against all odds, and it can reveal itself in unlikely ways. Traces of biology hide in the most unexpected locations. It’s why I roam the terrain at the edge of the world, hunting for the subtlest fingerprints of life, learning how to look.
In the far reaches of Australia, there’s one particular lake that stands apart from the others, amid the rocks and dunes, past the Rabbit Proof Fence and Jilbadji Nature Reserve, past the derelict aerodrome. The surface is stippled with halite, a form of table salt that looks like freshly fallen snow. In the right place, with a good grip, you can pull out a crystal of gypsum, severed like a shark’s tooth from the jaw of the earth. The spear-tipped blades are as large as your hand. When you rinse away the red mud and hold it to the light, it flashes in the sun like a gemstone. Under a microscope, you can see the tiniest of pockets within it: glinting drops of lake water, sheathed in mineral hideaways. Life caught in a crystalline dagger.
* * *
—
THESE PRISMATIC INCLUSIONS are just one of the many features we want to look for on Mars. We are seeking places where secrets are held, where traces of life might be preserved and protected. For over fifty years, we’ve been exploring Mars with telescopes, flyby missions, orbiters, landers, and rovers. We’ve scoured the surface for current life as well as indications of past life, for possibilities and actualities. The wild strangeness of the planet, with its tawny air and relentless red deserts, calls to us: With each mission, we grapple to understand a world that’s at once recognizable yet at the same time indescribably foreign. We return again and again, and the mysteries deepen.
In the process, we’ve built an entire field of science around something we can barely see in the night. Four hundred years ago, Mars was still a blaze of light, no more than an idea. The earliest telescopes showed it about as large as a pea held at arm’s length, and even more-modern telescopes gave us little to go on. We had no idea what the surface looked like or what it was made of, if there were mountains or valleys. We had only the crudest of maps. We didn’t know if there were clouds or what color the sky was. We started from almost nothing. We’ve gone careening down blind alleys and taken countless wrong turns, yet somehow, miraculously, the passion, ingenuity, and persistence we have brought to the enterprise have moved us toward a truer understanding of another world.
In this way, the story of Mars is also a story about Earth: how we’ve sought another stirring of life in the universe, and what that search has come to mean. Mars has been our mirror, our foil, a telltale reflection of what has been deepest in our hearts. We have seen in Mars a utopia. A wilderness. A sanctuary. An oracle. With so few landmarks, guideposts, or constraints, all is possible; without data that could be used to cabin our inquiry or limit our imagination, Mars has been a blank canvas. And tenderly, our human seeking has rushed to fill it.
As a result, Mars has a human history inscribed upon its surface, even though no human has ever touched it. This book offers an account of our exploration of Mars since the dawn of the Space Age, a relatively recent human effort that has revealed the planet’s extraordinary natural history. Most of the explorers in these pages—the modern scientists and the people from centuries past who inspired them—came to Mars seeking connection to something larger than themselves, some piece of evidence, some breakthrough observation that would show life could exist there. And they didn’t just seek it, they longed for it—I long for it—knowing that even the smallest glimpse of some greater, deeper, other realm might change everything. This is what sets Mars exploration apart: The quest to bring this distant world into focus, pursued over generations and on the frontiers of technological innovation, has always been about more than scientific knowledge. It has been an almost existential endeavor to confront our own limitations, to learn what life really is, and ultimately to defy our own isolation in the universe.
IN JULY OF 1965, as a tiny octagonal spacecraft swooped across the Martian surface, my father, who had just turned eighteen, was standing tall on a humid, hardwood-forested hill in Appalachia. There on the edge of Viper, Kentucky—below a hundred kilometers of nitrogen and oxygen, under the Kármán line, the exosphere, and the Van Allen belt, beneath the great, vast vacuum of space—a small natural-gas company had sent a bulldozer up a holler and had set about carving out a flat spot for drilling. On the days my father managed to drive the old jeep through the creek bed without flooding the engine, he joined an overalls-clad, illiterate crew in digging ditches and laying pipe, occasionally carrying the casing for the drill head. He’d hoped to spend the summer as a fledgling assistant to the company geologist, but within two weeks, every available worker had been sent to the hillside.
The news about the world’s first Mars mission, Mariner 4, came by way of The Courier-Journal, the newspaper out of Louisville. It arrived on a truck that twisted along the deeply gouged mountain roads, passed the coal camps, passed Hazard High School, and made its way into the small downtown, which was bound like a bobby pin by the North Fork of the Kentucky River.
That morning, my grandfather had picked up the newspaper from Fouts Drug. He’d tucked it under his arm on his way to work at the health department. As a medical technician, he inspected the Cold War–era bomb shelters that dotted the mountain ridges to make sure the food stocks were safe and drew blood to test for syphilis before young couples got married. He took pride in the fact that everyone in town called him “Doc.” He wasn’t a doctor, but he did give penicillin shots throughout the hills of eastern Kentucky: down in Gilly, up in Typo, in Slemp and Scuddy, in Happy, Yeaddiss, and Busy. When my grandmother wasn’t giving perms, she would help out. She liked running the X-ray machine.
It was still muggy later that evening as my grandfather meandered up Broadway—a street that was anything but broad, a single paved lane that fell steeply into backyards teeming with kudzu. He walked into a house that hung like a bat to the side of the ravine, leaving The Courier-Journal in the attic bedroom, which was spacious now that four of the six kids had left home. His lanky, wide-eared child, his youngest son, would also leave at the end of the summer, heading two hours west across the steep forested slopes to attend Berea College. My grandfather put the paper on the quilt where my father was sure to find it, next to his Popular Science magazine, right beneath a poster of the pockmarked moon.
My father had been spellbound by the idea of the mission, NASA’s chance to photograph the planet most similar to Earth. As the mountain town rotated into darkness that Wednesday, my father climbed the steps, aching and exhausted, and he saw the headline. Above the fold, between a picture of Willie Mays and an article on Vietnam, was what he’d been waiting for: MANKIND, THROUGH MARINER, REACHING FOR MARS TODAY. He smiled and fell into bed as he read. “Today the fingertip of mankind reaches out 134 million miles to Mars, almost touching the only other body in the solar system widely suspected of harboring life…”
On the other side of the country, in a canyon north of Pasadena, an eager crowd had gathered on the campus of NASA’s Jet Propulsion Laboratory. Inside JPL’s von Kármán auditorium, intertwined cables, thick and vaguely subterranean, unfurled from a cluster of television cameras and snaked across the floor to the vans outside. Radio from all over the world was hooked in by relay, and the Brits were poised to broadcast a live television feed, having leased a full two minutes of time from the “Early Bird” satellite. There were thirty-seven phones in varying states of use: thirty-six within the press bank, and one sitting atop a desk as part of a small fake office where the TV broadcasters could be filmed.
From floor to ceiling, dominating one side of the great room, was a full-scale spacecraft, one of the flight-ready spares that had been used for temperature-control testing. It had the same octagonal magnesium frame as Mariner 4, the same 260 kilograms of hardware and
instrumentation. There were 138,000 parts in all: aluminum tubes, attitude-control jets, pyro end cabling. The solar panels, including flaps at the end, stretched seven meters. Coated with sapphire glass, glistening in the beams of the television lights, they looked like the wings of a jeweled pterodactyl.
Much depended on this craft. In a scene that played out repeatedly over the course of the twentieth century, a Soviet spacecraft was approaching Mars at the same time. It had launched from the Baikonur Cosmodrome just two days after Mariner 4. It had reached Mars, but, much to NASA’s delight, it wouldn’t be returning any data. Halfway there, irregular updates had started coming from its communications systems, and then the transmitter died. It was now no more than “the voiceless ‘Russian spy,’ ” “The ‘Dead’ Soviet Mars missile.” At long last, the United States had a chance to pull ahead in the Space Race.
There was only one hurdle standing in the way of American triumph: Mariner 4 had to aim and actuate the camera and successfully transmit its images back to Earth. This was no easy feat. Mars was so far from the sun that the mission had only 310 watts of usable power, the equivalent of a couple of lightbulbs. The power available to send the data stream would be a mere ten watts to start, which would dissipate to a tenth of a billionth of a billionth of a watt by the time it was captured in the great dishes of the Deep Space Network, the newly built antennas on the outskirts of Johannesburg and Canberra, and deep in the Mojave Desert. And even if the data arrived, there were worries. What if the pictures snapped a bit too early, or a bit too late? What if the spacecraft inadvertently twisted away from the planet at just the wrong moment? What if the camera failed to shut off, recording over the photographs of Mars with pointless photographs of empty space?
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