The Sirens of Mars

by Sarah Stewart Johnson

  Eventually it started to look like Maria and Steve would have another shot. NASA was developing a new program for exploring Mars, based on smaller, less pricey spacecraft. A new mission called Mars Global Surveyor was selected for the 1996 launch window. Like Pathfinder, which would also launch in 1996, Mars Global Surveyor was part of NASA’s new “faster, better, cheaper” program. It was lighter than Mars Observer, only half the mass and size, but it would carry five of the same instruments, including MOLA. Maria would be the second-in-command of the instrument.

  Just before launch, a reporter called Maria and asked how it felt to be the only woman among the eighty-seven investigators on the mission’s science team. The question took her aback. How could that be true? But as she quickly scrolled through the names on the team roster, it became clear that the reporter was right. She realized that she must have stopped noticing things like that a long time ago. She had trained her thoughts entirely on bigger problems, like how to map Mars with breathtaking resolution—how to transform planetary cartography.

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  WHEN MARS GLOBAL Surveyor lifted into the sky in November 1996, Maria was in Florida. Her two children couldn’t have been happier because, to them, a launch meant a trip to Disney World. Everything seemed to be going according to plan. About an hour after blastoff, however—up in the silence, in the great vacuum of space—a tiny lever sheared off one of the spacecraft’s winged solar arrays as it tried to open. There was no sound as it slowly clinked along. It was no larger than a carabiner, but by some coincidence of physics, the trajectory sent it right into the five-centimeter hinge between the shoulder joint and the edge of the solar panel. With a tiny lever stuck in its hinge, the solar panel protruded away from the sun at an awkward angle, a good twenty degrees short of its fully open position.

  There was still enough solar power to reach Mars; the complications would come after arrival. The spacecraft had been designed to enter orbit using a radical new technique called “aerobraking.” The idea was to use the drag of Mars’s thin atmosphere against the solar panels to slow it down naturally, rather than drawing on precious fuel. This had shrunk the cost of the rocket by a factor of five, but it left little margin for error. And with a contorted solar panel, it wasn’t clear whether the aerobraking would work.

  Several times during the 309-day cruise, the engineers tried to wiggle the panel back and forth to free the stray piece of metal, but they had no luck. When the spacecraft finally reached Mars, the team decided to gently “walk in” to the atmosphere to see what would happen. By this time Maria had moved to Massachusetts. She’d been offered a senior tenured-professor position at MIT—something she couldn’t refuse. The university was putting an enormous amount of faith in her. The chair told her, “After Mars Observer failed, you should have disappeared. But you didn’t, and we think that’s for a reason.” She had barely moved into her new office when she got a phone call from mission control. The voice on speakerphone sounded concerned. “Well, the solar panel may have broken off. We’ll have to wait for the telemetry.” After Maria hung up, her secretary blanched and walked out of the room, avoiding eye contact. Maria took a deep breath.

  The panel hadn’t in fact snapped, but it easily could have. It had started to jolt, first stopping at twenty degrees, then flapping beyond its fully extended position, like a hyperextended knee. Terrified by the weakness in the joint, the team immediately lifted the spacecraft back above the atmosphere to figure out what to do. Tests soon showed that the springs holding the panel open wouldn’t withstand the atmospheric forces for long. It left the team with a big problem: Mars Global Surveyor needed to slow down dramatically, trimming its huge egg-shaped ellipse into a tight circular track. The only way to get into a mapping orbit was to aerobrake, but they couldn’t aerobrake without risking the solar panel.

  The engineers knew that fully closing the solar array wasn’t an option, as it would generate too much heat right up against the spacecraft, so they decided to tilt the panel so that it was in line with the atmospheric drag, thereby reducing the air resistance by two-thirds. As they sent the command to perform the tilt, they were aware that it would come with an enormous cost: It would mean looping an extra few hundred times around the planet before reaching a circular orbit, gently grazing the atmosphere each time the spacecraft swooped in close to the surface. The primary mission couldn’t begin until aerobraking was complete and Mars drifted back into the correct alignment with the sun. This would mean waiting another year and a half.

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  MARIA HADN’T SET out to be a mapper, but she’d always admired maps of Mars, including those that were drawn long before she was born. Their resolution was coarse by her standards, unable to capture the kind of details that would bring the planet to life, but the names of the features were full of meaning. Isidis, Arcadia, and Elysium—they all evoked a mythic, ethereal place.

  Most of the nomenclature of Mars had been developed more than a hundred years earlier, by the same nineteenth-century Italian astronomer who had identified the swarm of crisscrossing lines on the planet’s surface. Giovanni Schiaparelli also saw scores of other features that no one had seen before, features in need of names. Like Maria, he had been peering into space since he was a small child. He’d also grown up in a large family in a quiet corner of the world—the first of eight children born to a furnace operator in the Kingdom of Piedmont-Sardinia. Forging bricks and tiles out of the earth made for a hard life, but as a boy, there was lots of time to wonder and explore. Most Sundays and many winter days, young Schiaparelli would curl up with a book; one of his favorites was Geography for the Use of Princes. In the evenings, he would catch glimpses of the rings of Saturn from a telescope in the bell tower of the church.

  A few weeks after Schiaparelli turned thirteen, however, the king declared war on the Austrian Empire, only to be driven back to the foot of the Piedmont. He abdicated, and his son began his reign by suppressing insurrections, revolts, and rebellions as they arose. Sardinia teetered, and Schiaparelli departed for Turin, entering university at the age of fifteen. Given all the uncertainty—for his nation, for his family—he resigned himself to becoming an engineer: a solid, useful, profitable profession. He did well on the difficult exams, which culled his class from fifty-five pupils to fifteen, and at nineteen he took a degree in civil architecture and hydraulic engineering.

  There was no money left, and no scholarships, so he briefly took a position teaching elementary mathematics at a nearby school. He cut his budget to the bone. He lacked towels, he wrote to his parents in 1856 from his new post at the Gymnasium Porta Nuova, and he’d torn his best shoes walking through the meadows. He requested three or four buttons to replace his that had broken. In his shabby room, he spent his evenings engrossed in books, mostly about modern languages and astronomy, and he kept notes in a series of diaries. He wrote in both prose and poetry, in elegant cursive, alternating between Italian and his growing mastery of Latin, French, Greek, and Hebrew. He was often hungry, and that slowed him down. He found himself frustrated by how little he would accomplish by day’s end and, “what is worse, in things I can’t imagine ever being useful.”

  But then in 1857, with the help of one of his former professors, an unexpected opportunity to study astronomy came his way. He packed his meager things straightaway, overjoyed by the chance to go to Berlin to work with an expert in comets. His parents were startled and anxious, but he offered to write to them every step of the way—from Chambéry, from Paris, from Brussels, from Cologne, and finally from Berlin. “I am not going into barbarian country,” he promised, assuring them that France and Germany were “civilized nations.”

  Upon his arrival, he plunged into the work at hand while also exploring philosophy, geography, meteorology, physics, and terrestrial magnetism. He devoured the canon of Friedrich Schiller’s dramatic works, dabbled in Indology, and began learning
Arabic and Sanskrit. Two years later, he traveled to Potsdam, then sailed to St. Petersburg for additional studies at the Pulkovo Observatory, where he worked under a pair of father-and-son astronomers. Soon word came of a job offer. He would begin as the secondo astronomo—the “second astronomer”—at the Royal Observatory in Milan. He promptly spotted a new asteroid—he called it Hesperia, “hope”—then shortly thereafter discovered that shooting stars were in fact the tails of comets.

  A few years later Schiaparelli turned his attention to Mars. In the summer of 1877, from an observatory situated on the rooftop of the Brera Palace, he began jotting down notes about the peculiar features he saw. First, he cleaved the globe with a giant diaframma, a north-south dividing line between the darker and lighter areas. He split the bright areas into a drove of islands and gave them names like Zephyria, the home of the west wind; Argyre, a mythical island; and Elysium, the land of dead heroes. To the west, inside the Columns of Hercules, he mapped the dark seas: Mare Tyrrhenum, the sea of the Etruscans; Mare Cimmerium, the sea of the Thracians; and Mare Sirenum, the sea of sirens. To the north were the stomping grounds of Arcadia, and to the east was Solis Lacus, the lake of the sun.

  Schiaparelli drew from Herodotus, the Odyssey, and bands of heroes in Greek mythology. Some of his names reprised moments of magnificence, like the journey of the Titan god Helios, who drove the chariot of the sun across the sky. He traced its path across Mars as he labeled the landscape, from the Orient with Chryse and Argyre—Thailand and Burma—to Margaritifer Sinus—the Pearl Coast of India. He drew from religion, borrowing names from the Bible: Alongside Arabia was Eden, large and bright. There were touches of sadness too, perhaps a holdover from the “black melancholy” he felt in his youth, or a sense of unease in the world. There were chains of smoky lands and blackish lakes. There was Memnonia, a leaden patch that sometimes whitened, but only in winter. There were also features named for places on Earth that had never been found by modern explorers, like Phison and Gehon, the lost rivers of Mesopotamia. And the whole map was upside down. His telescope inverted the image, and he found it easiest to draw and think about Mars with the same view.

  It was, by his own admission, “a curious and disordered arrangement.” But taken together, it evoked a human cultural history, a place intertwined with our own existence and filled with the promise that our grandest ambitions might be resurrected. He had covered Mars with beautiful names, names that would filter down through the generations.

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  BY THE TIME Maria reached MIT, she too was becoming a mapper. Slowly, surely. She had initially thought about a career as an astronaut, going so far as to submit an application before quickly withdrawing it. She’d wanted to have children and couldn’t quite fathom leaving them behind, particularly in the wake of the Challenger accident. But she soon discovered that there were many ways to explore and that probes built by human hands could take her farther than a space station in low Earth orbit ever could. Spacecraft could open up possibilities far beyond human reach, throwing light onto far-distant worlds.

  At the same time, she knew that the field was one of high risk and high reward—that no one sets off for the frontier with any reasonable feeling of certainty, and that space exploration lives and dies on the knife-edge of technology. She had felt the sting of that herself with Mars Observer. Yet, collecting data, any data, directly from Mars was a rare opportunity. And so, while the aerobraking delay had been a frustrating setback for everyone, Maria was determined to make the best of it. As luck would have it, even though the orbit was far from ideal, there were a few months when getting some mapping data was possible. Those periods fell outside the phases of aerobraking, when the spacecraft was not passing through the atmosphere, allowing the instruments to safely deploy. When they did, the spacecraft’s periapsis, the point of the orbit nearest to the planet, was over the North Pole. Maria was thrilled to have the chance to test her instrument, and soon things were starting to look good for MOLA: Using the preliminary data, Maria was able to render a beautiful three-dimensional model of Mars’s North Pole. She rushed the findings to press in Science, just in time for Christmas. It was a wonderful taste of what was to come.

  But as she waited for another bite at the apple, she couldn’t escape reminders of the risks. Though her polar article dominated the Mars news cycle when it came out in December 1998, NASA had launched a new mission to Mars on the same day, to study the planet’s climate. Like Pathfinder and Mars Global Surveyor, Mars Climate Orbiter was a low-cost affair, the third mission designed under NASA’s mantra of “faster, better, cheaper.” Throughout the journey, the trajectory had required minor corrections, far more than usual, but it hadn’t raised many eyebrows. It was only when the spacecraft reached Mars that mission control knew something was wrong. The signal dropped as the spacecraft arced behind Mars for the first time. But it dropped forty-nine seconds earlier than expected, and it never returned. Within half an hour, it was clear that it had hit the top of the atmosphere and disintegrated, the result of a mix-up between English and metric units in the navigational commands.

  Within a couple of months, another “faster, better, cheaper” Mars mission failed. It was the same mission I’d made a tiny contribution to, with all those experiments in the Mars Surface Wind Tunnel to assess the dust loadings on solar panels. Mars Polar Lander nearly touched down at Ultimi Scopuli, in the south polar terrain, among canyons carved by katabatic winds and dark dunes that bloomed like flowers. But the onboard computer misinterpreted a jolt from the lander legs. Sensing touchdown, it sent a signal to shut down the descent engines. The spacecraft fell forty meters, impacting the surface at high speed.

  When Maria entered the field, she knew it would be the ultimate in high-stakes science. Half the missions to Mars have failed: Some, like Mars Observer, sailed silently by the planet; others crashed hard, littering their wreckage across the surface. Strewn about the sands of Samara are hunks of metal and tangles of wires. West of Alpheus Colles, there’s a pennant with the state emblem of the Soviet Union. The lifeless solar panels of a British astrobiology mission, one still folded like a lawn chair, gather dust on the plains of Isidis. And somewhere in Ultimi, there’s an American CD-ROM, likely shattered, that once contained the names of a million schoolchildren.

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  AFTER MARS OBSERVER, Maria felt like she’d utterly failed—an above-the-fold, front page of The New York Times kind of failure. It was not a good feeling, but eventually she learned to draw strength from the experience: Anytime something went wrong, she would think, “How bad could this be? Worse than losing your spacecraft three days before reaching Mars? Probably not.”

  Mars Global Surveyor had been imperiled, with its wing dragging in the Martian night. But much to Maria’s relief, the mission didn’t end up as another character-building experience. Far from it. It would become one of the most successful in NASA’s history. In just the first two years of mapping, it collected more data than any previous Mars mission, with MOLA leading the charge. Each day, 900,000 laser bursts were shot at the planet, and the topographical measurements they returned were superior to those we had for vast regions of the Earth. The data gave us everything: heaps of phenomena that affect the Martian surface, from volcanism and cratering and deformation to the erosional and depositional action of water and ice.

  Maria and her team used the data to fill in their Technicolor map. From the sunken lowlands—a deep cerulean blue—the crust heaved forward in a riot of reds and purples, as if lava were still bursting from the planet’s distended side. There were maze-like valleys and jagged fractures and mountains on pedestals. The polychromatic gash of Valles Marineris reached impossibly deep—nearly five times as deep as Africa’s Great Rift Valley—before giving way to the crenulated ramparts of Noctis Labyrinthus.

  Yet nowhere among the splayed lowlands or heavily cratered highlands were obvious ea
rthquake faults or mountain belts, which would have been expected if the planet had plate tectonics. The southern hemisphere had been punched by a massive asteroid at some point in the deep past, as evidenced by an enormous depression. Hellas basin had been studied before, but no one had realized it was deep enough to swallow Kilimanjaro. On the map, it was a piercing purple-blue, like a giant round eye. It had a kilometer-and-a-half-high rampart, so it must have thrown out enough material to cover the continental United States in a three-kilometer blanket of rock. The impact might have whacked Mars hard enough to irrevocably disrupt heat flow across the core-mantle boundary, turning off its magnetic field forever, allowing the planet’s atmosphere to float away.

  The precision of the map allowed Maria to read the planet’s history like a type of braille. As hinted by the initial data, the northern hemisphere proved to be the smoothest surface that had ever been observed in the solar system. Most of the terrain seemed to tilt slightly to the north, suggesting that a planetwide drainage system may have once emptied there, into a great northern ocean. Inscribed onto the surface was even a possible shoreline, Deuteronilus, which could be traced for thousands of kilometers. The coast ran along nearly the same elevation, with variations that could be explained by the ground rebounding, exhaling as the weight of a sea of long-gone water evaporated. With each new detail Maria plotted, another aspect of Mars’s history came to life.

  Mars Global Surveyor changed what it meant to see a planet. If the old map of Mars was a simple picture, the new map was a portrait. It went beyond what our eyes could take in, capturing data on contours, on composition, on forces we could not see—not just topography but things like magnetic signals and mineral compositions measured out beyond the visible wavelengths. There were subtleties to be seen—we just had to get there, and when we got there, we had to know how to look.