The Rock From Mars (8 page)

In a way, that was how he had gotten his nickname—by putting something off. As an undergraduate at the State University of New York at Fredonia, he’d waited until the last possible moment to do a laboratory assignment due the next morning. A substitute professor had assigned a huge batch of rock samples he’d (wrongly) assumed the students could analyze easily in four hours. Mittlefehldt and several others started after supper that night. Four hours passed, and they were still there. Things started to get crazy toward the shank of the night, and Mittlefehldt admitted to his fellow sufferers that he was “cracking up.” Someone turned that into “quacking up.” And then they started calling him Duck. (“You really had to be there,” he would say later, shaking his head.) But he finished the work and was one of the first to leave, at around three
A
.
M
. No problem. Lab class wasn’t until eight
A
.
M
. He had not only completed the assignment, he had acquired a lifelong monicker.

It followed him to UCLA, where he earned his Ph.D. in geochemistry, to the University of Arizona, and through a sojourn in Israel’s Negev, on the faculty of Ben-Gurion University. He was still Duck when he arrived in Houston, in September 1985.

In July 1993, he was forced to end his laissez-faire approach to the mystery of the rock’s lineage because of what happened when he finally wrote his paper on the origins of the common meteorites, the paper he had been working on for five years. One of the anonymous experts assigned to evaluate Mittlefehldt’s paper before publication, as part of the routine process, criticized the work, chastising Mittlefehldt for his handling, or nonhandling, of the questions about the weird signature in that particular sample.

Mittlefehldt realized he had to crack the case. He went back to the electron microprobe with his little glass-mounted bits and set the magnification as high as he could. He checked and rechecked, and rechecked again, all through that summer. He compared this sample with other meteorite samples he had analyzed on the same day, in the same way, as this rebellious one; the others all had the “correct” signature and this one (still) did not. He finally convinced himself that his analysis had
not
been in error. The signature in the specimen was truly different. Now he had to confront the implications.

Mittlefehldt thought over the whole sequence of experiments—and tried to liberate his mind from those ditches of conventional thinking, to sort through his wider mental inventory.

About three years earlier, Mittlefehldt had read up on Martian meteorites just to make sure he was current. He knew NASA was gearing up to send a new generation of robotic geologists to Mars with the ultimate goal of bringing back pieces of Martian rock and soil, and he wanted to be in a position to do some of the analysis on the Mars samples. He had kept up with the subject. You never knew when something important, something you could use, was going to turn up.

Now it struck Mittlefehldt that there was one family of rocks where this frustrating, weird one would fit in nicely, geochemically speaking. The SNCs. Of course. SNCs (pronounced “snicks”) were a tiny family of stones that shared characteristics with one another but contrasted dramatically with the dominant meteorite population. The SNCs were Martian.

The acronym SNC refers to the lyrical names of the sites where three of these stones had been collected over the span of almost a century: the French village of Chassigny (1815), where people heard loud sonic booms and saw a stone weighing about nine pounds (four kilograms) fall from the sky; the town of Shergotty, in India (1865), where people heard similar booms and saw an eleven-pound (five kilogram) object fall; and the village of El-Nakhla, in Egypt (1911), where witnesses reported the impacts of multiple fragments that fell in a shower from the explosion of a single meteorite higher up. People reported that one of the objects killed a dog. In that case, scientists recovered some forty stones with a collective weight of about twenty-two pounds (ten kilograms).

Shergotty, Nakhla, and Chassigny . . .

Scientists had not arrived easily at the recognition that the SNCs came from Mars. Many found it preposterous to imagine that a chunk of that planet might reach Earth’s surface on its own—a gift of nature—in a relatively unaltered state. Surely any impact violent enough to knock a rock off a planet would alter the specimen beyond recognition, or vaporize it completely. In the early 1980s, the experts had to stop scoffing when geochemist Donald Bogard and his coworkers finally found convincing evidence to the contrary.

Bogard, working at the Houston complex, wondered why this group of meteorites stood out from the crowd. In a landmark study of one such specimen, he and a colleague heated black glass (formed inside the rock by a violent impact or shock) and analyzed the trapped gases that bubbled up. Clever detective work led them to discover that the chemical composition matched perfectly that of the Martian atmosphere—which was unlike that of any other known body. And how had Bogard known what the Martian atmosphere was like? The robotic U.S. Viking spacecraft that landed on Mars in 1976 had sent a direct analysis of it back to Earth.

Through “guilt by association,” as one scientist put it, the other oddball meteorites with similar compositions to this one (and to Mars) were deemed to have made the trip from Mars as well.

This amazing pilgrimage of stones was part of a portrait then emerging of the solar system as a vast pinball gallery, a tarantella of spheres and rough chunks sweeping around the sun on random tracks that sometimes brought them to the same point in space and time. Humanity had finally begun to grasp the profound importance of cataclysmic impacts in shaping the history of the solar system, of Earth, and of all life, including human evolution. The killer rock that wiped out the dinosaurs—an extinction scenario that just recently had won scientific acceptance after years of controversy—was the most celebrated instance.

Human awareness of the glittering firmament as a threatening presence would take another great leap in 1994, with the unprecedented “live” spectacle of shattered comet fragments ripping into Jupiter’s gaseous surface, kicking up towering plumes and leaving dark bruises in its swirling pastels. The event would be recorded by most of the world’s telescopes, heralded by the media, and followed intensely on the emerging Internet. Afterward, visions of lethal celestial “incoming” would proliferate in books, movies, magazine articles, television documentaries, and the public imagination.

Fortunately for civilization, most of the cosmic rubble that peppered Earth was small. In this context, respectable scientists had long speculated about whether the planets and other cosmic bodies might have “swapped spit” and seeded one another with living organisms. Recent and ongoing spaceflight experiments indicated that at least some hardy microbes could survive a journey across the vacuum of space—if they were somehow shielded from deadly, DNA-wrecking radiation.

As Mittlefehldt fretted through the waning summer of 1993, of all the thousands of meteorites studied, only nine—the SNCs—had been identified as Martian. Sitting there in the hush of Building 31, he strongly suspected that he was looking at the tenth known piece of Mars.

Mittlefehldt was still wary. His insight resolved only part of the mystery. This rock was weird; its composition made it some kind of strange outlier
—
even among the SNCs. He wanted to do a bit more sorting out. Meanwhile, he worked on his main project—and a funny thing happened.

He had accumulated a good many samples of asteroid-spawned meteorites. As he studied them, he saw one with a familiar label. It was another presumed piece of old friend Vesta, picked up in Antarctica. To his astonishment, this sample showed some weird signatures, including one that matched up with what he saw in the Allan Hills rock. The readings now were also quite different from his readings the last time he had studied a sample with this same label.

Then he saw the whole picture. He was in the lab, looking at columns of atomic ratios, and seeing far too much sulfur for any run-of-the-mill meteorite. But the reading was typical . . . in
Martian
meteorites. (He checked the calibration of the microprobe, just to be sure the reading was no mistake. It was fine.) He backed up and took another look at the sample, imagining it as a whole individual, personality and all. Now he noticed that the texture was “wrong” for an ordinary Vesta-type meteorite. In fact, the texture was just like that of the meteorite from Allan Hills, which he had seen intact in pictures. It hit him: this
was
an Allan Hills chip, had to be. He had a
second
mislabeled sample.

That fluky reading was the clincher he had been looking for. “Everything clicked,” he would say later. He all but screamed “Eureka!”

He knew he not only had a Martian meteorite but a special one at that. He would recall later with a grin, “It was the most satisfying experience of my life . . . knowing that other people had studied [the rock] and hadn’t tumbled to it.”

Mittlefehldt, like many others, had been boning up on Martian meteorites for practical reasons. After a hiatus that began in the mid-1970s, U.S. robotic missions to Mars were about to resume. Whatever else it might or might not have, Mars had funding.

The last rocky planet out from the sun before the asteroid belt and the succession of giant gas worlds, Mars was a miserable, dry, dust-blown, cold, and barren desert world. And yet, for some, it sang like the Sirens. It was the most Earth-like body known to exist anywhere. That plus its nearness made it seem most likely to end the cosmic aloneness of Earthlings. (The surface of Venus was hot enough to melt lead and shrouded in a poisonous atmosphere with one hundred times the atmospheric pressure on Earth; Mercury, closest to the sun, was as airless as Earth’s moon, its surface cooked by solar radiation with ten times the intensity of that on the moon; at least one satellite of Jupiter might conceivably harbor life, but the Jovian system generated belts of powerful, deadly radiation; and the intriguing moons of Saturn were a daunting billion miles from Earth, with just 1 percent of the sunlight.)

Mars was our sister world, the familiar red beacon in the night sky. Although it appeared at best only one-hundredth the size of the full moon, it was the only planet whose actual surface could be seen with the naked human eye. (The surface of Venus was obscured by that atmospheric shroud; that of Mercury, by its proximity to the sun. The other planets were too distant to see unaided, and most had no defined surfaces.)

Mars and Earth lived in the Goldilocks zone, where the sun’s heat was neither too strong nor too weak to sustain life (as we know it). The Martian day was only slightly longer than Earth’s (although its year was almost twice as long). The Martian night could be worse than the Antarctic, at minus 125 degrees Fahrenheit.

The low temperatures and pressures on Mars meant that any liquid water reaching its surface would rapidly boil off, freeze, or poof into vapor. But the daytime sunlight—about half as strong as that on Earth—would sometimes heat rocks and soils above freezing. And the north and south polar frost caps, showing water ice exposed at the surface, might someday be converted to provide an abundance of the most basic of human needs. Scientists theorized that water must also be locked up in permafrost not far beneath the Martian surface, within reach of drills, and that the soil might contain water bound up in mineral grains.

Its similarities to Earth and its neighborly nearness made Mars the most rational next destination for human space explorers and, Duck Mittlefehldt thought, “one of the more plausible future habitats for humanity.” Beyond its practical appeal, Mars was the object of a yearning—for the promise of kinship with other living beings in the vast and empty blackness, for a mirror to be held up against the infinite wilderness to show us who we are. Or are not. And what our future might hold.

The human romance with Mars had flickered and shifted over the centuries. Early telescopes showed linear tracings on the reddish surface that prompted speculation about artificial construction by unknown engineers; seasonal changes suggested the blossoming and retreat of vegetation. Even then, water was the overarching enigma, the thread wound throughout the Martian mystery. In the speculations of Percival Lowell, canals carried water from the poles to nourish an advanced civilization concentrated in the equatorial deserts, where the climate was no harsher than, say, that of “the South of England.” Life-giving waters flowed through the Mars novels of Edgar Rice Burroughs, and H. G. Wells conjured a Martian race of “intellects vast and cool and unsympathetic.” Poet of the possible Ray Bradbury, writing in the 1940s, described doomed yellow-eyed Martians keeping house beside an empty fossil sea on that “dead, dreaming world.”

Duck Mittlefehldt was about to drop a catalyst into the drama of the search for life on Mars, which had been a driving force of the U.S. space program since almost the beginning. A landmark report by independent scientists in 1962 chose “the search for extraterrestrial life as the prime goal of space biology.” Not since Darwin, and before him Copernicus, they wrote, has science had “the opportunity for so great an impact on man’s understanding of man.”

With the dawn of the space age had come the disillusionment of icy fact—the day in 1965 that Mariner 4 swept over a frosty slice of ancient cratered terrain to provide Earth’s first fleeting close-up of its neighbor, a snapshot of a world bleak and dead. Mariner 9, the first Earth ship to slip into orbit around Mars, brightened the outlook a bit with evidence of a more interesting and changeable world. Water had once flowed there, the polar caps had ice in them, they expanded and retreated as the seasons changed, and there was water in clouds that drifted in the Martian skies.

Encouraged, scientists pressed more aggressively on the big question: Was there any hint of life? To the young scientist and soon-to-be-celebrity Carl Sagan, the Mars of today strongly evoked an Earth he had seen in Colorado and Arizona and Nevada. And he noted that, for much of history, “those regions of Earth not covered by water looked rather like Mars today—with an atmosphere rich in carbon dioxide, with ultraviolet light shining fiercely down on the surface through an atmosphere devoid of ozone.” Though large plants and animals had come along in the last 10 percent of Earth’s history, “for three billion years, there were microorganisms everywhere on Earth. To look for life on Mars, we must look for microbes.”