The Rock From Mars (10 page)

“Yeah, right” had been Romanek’s unspoken reaction. “How do you know there
are
any meteorites from Mars? How could you ever figure that out, anyway?” It was only after he’d arrived at the space center and started talking to folks like Don Bogard, who had actually done it, that he changed his mind.

In fact, he was hooked. When Duck Mittlefehldt first summoned him to see the intriguing images of the Mars rock that November evening, Romanek was busy shooting his laser at a piece of a well-known meteorite that had fallen in Murchison, Australia, in 1969. The Murchison meteorite was a piece of the primeval rubble that coalesced at the birth of the solar system, just over 4.5 billion years ago, and had remained relatively unaltered since then. Other scientists had revealed that it was packed with amino acids—more than seventy different kinds, most of them not from Earth—and other molecules important for the development of living things. But the evidence also indicated that these basic building blocks of life had
not
been left in the meteorite by any living thing. The material lacked the specific signature that goes hand in glove with all known life—a distinctive chemical “handshake,” a form of molecular right- or left-handedness.

Now Romanek interrupted his assault on the celebrated Murchison meteorite in favor of Duck Mittlefehldt’s alluring newcomer. With his laser blaster, he would try to figure out what had been going on in the Martian environment when those carbonates formed, to unspool the history recorded in the rock’s little “tapes” just as he had once done with those clam shells.

Romanek, in this case, would be studying the ratio of light carbon to heavy carbon found in the rock, and the same for its oxygen. The proportions amounted to messages recorded by nature. These isotopes were not the unstable type that decayed radioactively—the kind used to determine the age of the rock. These were stable sorts, and they told a different kind of story. By studying how nature had divvied up these variations in the atomic properties of a chemical element, a specialist could tell something about the temperatures present at the divvying, and possibly about how fast it had happened and in what sort of event, and whether the process had involved biology or not. (As is the case with most records, these signs could be ambiguous, open to differing interpretations.)

The isotope business, as it happened, was booming. Scientists were using isotopes to determine the frequency of certain volcanic eruptions and landslides; they were studying isotope ratios in molted bird feathers and butterfly wings to determine the points of origin of these migratory creatures; they were using isotopic measurements to trace the spread of contaminants in natural food systems; they were studying isotopes in grizzly bear food sources and bear hair to monitor changes in the grizzly diet; and the like.

If carbonates were typically formed from solutions, Romanek thought, then in the case of the Mars rock maybe waters flowing on that planet, saturated in carbon dioxide, had deposited the minerals. Enticed by Mittlefehldt and with Gibson’s blessing, he followed his impulse—to go into the rock with the nicely focused, modest aim of “just understanding the chemistry of the carbonates.”

In the course of the isotope work, Chris Romanek remembered having heard about another technique, one used recently to study carbonates found in hot springs on Earth. Simply put, you used acid to etch away surface material so that what was buried farther down—the internal structure—could be studied. He realized that the carbonates in this rock were plentiful enough, and large enough, that he could use the same technique.

He used water to make a dilute acid, etched the first sample, and popped it into the scanning electron microscope. What he saw there stopped him cold. He stared at the magnified spectacle for maybe half an hour, not believing his eyes. Could it be?

He was seeing “these bacterial forms all over the place,” he would recall later. “I was wondering, you know, am I going to get sick from touching this?” A thought about the fictional Andromeda strain might have flashed through his mind. He headed toward Gibson’s office.

He felt a little bit frightened, he had to confess, because these things—they looked exactly like living organisms.

CHAPTER FOUR

E.T.’S HANDSHAKE

C
ONTAMINATION.

Everett Gibson, the senior isotope specialist working across the hall from Duck Mittlefehldt’s lab, stared at Romanek’s buggy little shapes. Gibson spent a moment scratching his head before he realized what had happened. He had been seeing it for a quarter century.

Gibson, fifty-three, was an affable man with a sprawling West Texas accent, a mustache, and a sculpted wave of hair peaking atop his face. His ready grin was sometimes undercut by a tension around the eyes.

Gibson had joined NASA’s geochemistry team in Houston in 1966, about a year behind David McKay. In contrast to McKay, Gibson was bold, feisty, eager to “push the envelope,” and he loved to talk about his work. Gibson was known as something of a free spirit, prone to enthusiasms that would sometimes color his judgment.

When Gibson had arrived at NASA, he’d planned to study water in lunar rocks. It turned out there wasn’t any. So instead, he’d taken an interest in more general studies of the moon’s geochemistry. For sport, Gibson served as flight engineer in a B-17 Flying Fortress that he and others had rebuilt.

Like many others in this summer of 1994, Gibson was intrigued by the hot new Mars meteorite ALH84001, Robbie Score’s rock from Allan Hills. In the months since its unveiling, researchers had quickly shown it to be the
oldest
rock known from any planet, three times the age of any other sample from Mars and the first Martian fragment to come from
beneath
the planet’s surface. It was the only one laced with a high concentration of carbon compounds and therefore possibly an unprecedented indication of primordial carbon stored on Mars.

These attributes made the rock an object of intense desire, a rock star. In the months since Mittlefehldt had revealed its true identity, labs in Germany, Switzerland, India, Denmark, Austria, Japan, England, and all across the United States had requested samples of it. In fact, of the 150 samples of the rock distributed in the nine years since Score had retrieved it from Antarctica, curators had distributed well over half within about the last six months—not even counting the allocations to Mittlefehldt himself.

David McKay, too, had begun to take a hard look at the rock. In the years since Apollo, he had “done” moon dust and moved on to tackle cosmic dust—the itinerant particles that drift through “empty” space. He had been analyzing that material for carbon—searching not for signs and portents of
actual
biology but for carbon itself, because of that element’s importance as a building block for living things, as a precursor or enabler of life.

And that had led him to meteorites, including some from Mars. Now he had access to this complicated, fractured-up newcomer. His initial intention was to study this one in search of . . . more dust!

Under Gibson’s guidance, however, Romanek’s creative scrutiny of the carbonates was turning their particular investigation onto a radically different path from all the others. Soon McKay would make the same turn.

Gibson and his young assistant stared at the infestation in Romanek’s microscope pictures, and even before Gibson could react, Romanek realized his mistake. He had used laboratory water to dilute the acid he’d used to etch the rock sample. He realized that he had not filtered the water, and it was swimming with bacteria
—Earth
bacteria.

There may have been some sighing, some rolling of the eyes. In any case, Romanek wheeled around and went back to his bench for a do-over. This time, he filtered the water (and when he examined the filters, he could see that, as expected, they had trapped a mess of bacteria). When he looked at the microscopic landscape again under the scanning electron microscope, he no longer saw teeming bacteria. But . . . the shapes that remained still seemed eerily familiar.

He went back to Gibson with the cleaned-up images. When Gibson saw them, he thought to himself, “This is just bizarre.” If this were any terrestrial rock, you’d look at these features and say, oh, yeah, of course, that’s the influence of biology.

Romanek, the new kid, and Gibson, the seasoned veteran, were flirting with a wild notion.
They might, just might, be staring at evidence of once-living Martians.
It was enough to trigger butterflies. Romanek’s momentary diversion by the errant lab bugs might have been a symptom of this edgy mind-set.

In the preceding months, Romanek and Gibson had been getting a second line of encouragement for this outlandish idea. When Romanek was not etching the rock with acid, he was blasting it with his laser. He would train the beam on a fractured surface of rock sample where there was a concentration of the carbonate globules. His target area was about half the diameter of a human hair (20 to 40 microns). The laser would hit the spot and melt the mineral, releasing its carbon dioxide gas. The lab team would capture the gas and analyze its isotopes against accepted international standards.

Gibson considered the results nothing less than shocking.

The carbon signature, it had turned out, was so unearthly that it confirmed for Romanek and Gibson that the carbonates had indeed formed on Mars and not on Earth during the rock’s long sojourn in the Antarctic ice. It also seemed to rule out an association with biology.

As for the oxygen part of the story, Gibson and Romanek found that the carbonates had formed at temperatures in the biological Goldilocks zone—not too hot, not too cold, and, conceivably, just right for life to exist.

These results were so unexpected that Gibson sought independent confirmation. He knew that a group of geochemists and meteorite specialists in Britain had a sample of the same rock. One was a longtime colleague named Colin Pillinger who specialized in isotopic analysis. Gibson made the transatlantic call to his friend:

“Colin, have you analyzed eight-four-double-oh-one for its carbonates?”

“No we have not, it’s in our queue.”

“I suggest you move it up in the queue.”

“Why?”

“I’d rather not tell you our numbers, but I’d like for you to, if you would, move it forward.”

Ten days later, Gibson got the call back from England. Neither party wanted to divulge first. Gibson thought the Alphonse-and-Gaston routine was kind of funny. “What did you get?” “Well, what did
you
get?” Eventually they told each other their numbers.

The numbers were identical.

When those carbonate globs, about five times the diameter of a human hair, had been deposited in the rock, fizzy, carbonated liquid water was flowing on Mars at temperatures moderate enough for life to exist. That was the scenario the British numbers seemed to confirm.

The journal
Nature
would publish a paper by the Gibson and Pillinger groups in its December 1994 issue. It drew only minor attention, even though it was the first significant analysis ever done on carbonates in Martian material. The news reports focused mainly on the similarities between water from Mars and the fizz in soda drinks. And the insider reaction to the joint paper was: Wow, that is unusual carbon—probably a signature of the Martian atmosphere.

Everett Gibson had grown up in West Texas. When his family moved to the town of Hamlin, north of Abilene, he had camped and hiked in the mesquite river bottoms and worked the oil fields, too, for four summers. He saw what was beneath the surface. He saw cores come up from oil wells. He saw people get hurt, and he saw what a rough life it could be. He worked the oil fields in order to pay his way through Texas Tech, where he earned bachelor’s and master’s degrees in chemistry, but he didn’t want to make it a way of life.

Having developed an interest in the space program, and in meteorites and other extraterrestrial materials, Gibson went to Arizona State University for a doctorate and then joined NASA.

Gibson was proud to be one of the few lunar sample investigators in the most competitive science program in the history of the world. The NASA scientists had to compete for the same research dollars with counterparts at MIT, Harvard, Princeton, Caltech, and other major universities. The proposals were all thrown into the same pot, and reviewed by outside experts—peers. It was cutthroat, and he survived.

During Apollo, Gibson and the other rock detectives were working in such virgin territory they were obliged to develop new tools. A traditional Earth geologist could drive out into the field, bring back a truckload of rocks, and break them up with a hammer for inspection. Nobody knew how much the Apollo astronauts would bring back, or how much material any researcher would get his hands on. But it was clear that the allotments would be measured in mere milligrams. A fraction of an ounce of sample would be considered elephantine. The space-age investigators had to learn how to play Sherlock Holmes with the most minuscule of crime scenes.

Accordingly, Apollo spun off a fountain of money to address the need for a radical new approach. It was a source of great satisfaction to Gibson that he contributed to the creation of new techniques and tools (specific element detectors, gas chromatographic techniques, mass spectrometers, and lasers) that were high-tech equivalents of a precision hammer and chisel. These techniques were applied, among others, to the new Antarctic meteorite collection that began to accumulate upstairs in the mid-1970s. “If I have a strength,” Gibson would say, “it is the development of unique analytical capabilities.”

The Apollo program also taught Gibson a hard early lesson about the difficulties of coping with contamination in laboratory research, and the special effort it took to isolate a specimen entirely from the teeming, crawling, infested, blooming workaday Earth. The kind of contamination in question here was not simple befoulment; it was a kind of lie. This contamination could fool you, distort your reading of the evidence.

In the laboratory, a research specimen might pick up contaminants from water pipes and commercial fluids (as Romanek’s
Andromeda Strain
moment would remind him). And, depending on the techniques, contamination could come from cigarette ashes, human hair, dandruff, nose drips, dust and spores in the laboratory air, lint fibers from cleaning rags, fragments scraped off tools, or dead insect parts. Biological or otherwise, contamination was a constant concern; precautions against it, and efforts to identify it when it occurred, were part of the research routine.

One of Gibson’s first civil servant jobs was to help clean up the cabinets where the first Apollo samples were stored in the new Lunar Receiving Laboratory across the parking lot from Building 31. Not many people knew it, but in those early days, there were serious problems in NASA’s handling of the precious specimens. Gibson would recall that experience often in the months and years to come, when contamination would become an issue in his life again, when in fact he’d find himself under attack because of this rock and he’d want to impress on a listener his hard-bought understanding of the pitfalls.

No matter what sample you were analyzing, and no matter how precise and accurate your analysis, he knew you always had to consider how the sample might be trying to fool you.

In the mid-1980s, Gibson decided to learn more about this business of stable isotopes and went for a year of study with Pillinger at Britain’s Open University. Pillinger’s strength was in isotopic analysis, which Gibson aimed to couple with laser techniques in meteorite studies. When he got back to Houston, he started putting together a stable-isotope lab.

Johnson Space Center, however, was still geared to human spaceflight as its primary function. Meteorites and isotopes were a ways down the list. Accordingly, Gibson did not limit his focus too much. For a time, he partnered with a nutritional expert to figure out how much energy an astronaut uses in the weightlessness of space so that the space shuttle flight planners could set the proper exercise regimens and food requirements for orbiting crews. The project was a success and, most important, enabled Gibson to buy the equipment he needed to do what he really wanted to: study meteorites.

A natural storyteller, Gibson was known to twirl the dial on a combination safe in his lab complex, reach in, and pull out a piece of fallen sky for a visitor to hold—for instance, a heavy chunk of black rock that fell in February 1969 in Mexico. That meteorite had dumped about five thousand pounds of material on a village, he would explain.

“The local priest called all the people together in the church,” he’d say, “and asked them to pray for forgiveness. Then outsiders started showing up and acquiring the material, giving them rewards. So the priest called the people back together in the church”—here he would smile—“and they prayed for another one to fall.”

It was only when Gibson took up the study of
Martian
meteorites that he finally struck water—the commodity that had eluded him on the moon. His team heated samples from six of the SNCs—the Martian meteorites—in a series of steps, in a small vacuum system, to extract trace amounts of water. They then hand-carried the water samples to the University of Chicago, where researchers analyzed the oxygen isotopes.

Gibson and the others announced their discovery in a 1992 paper, which created a ripple among planetary scientists. He kept in his office a photograph of an actual drop of the “Martian water” just one-sixty-fourth of an inch in diameter. He showed it off proudly: an image showing a glass tube with a drop of water inside, and an arrow pointing to it.

Spacecraft investigations suggested that Mars might once have had a water-rich atmosphere and flowing waters on its surface, but that water had mysteriously disappeared. On the chill and arid planet Mars had become, the consensus remained that any flowing water that reached the surface could not stay liquid.

Gibson’s isotopic studies of the meteorite water droplets indicated that there were two separate and distinct populations, or reservoirs, of oxygen on Mars. By contrast, on Earth the oxygen is all essentially the same, whether in the atmosphere, oceans, or rocks. It has been homogenized by the mixing and churning of plate tectonics (the stately grinding of pieces of planetary crust, into and over one another, a process that unifies and explains much of Earth’s geological evolution). On Mars, the water apparently had a different parent source from the oxygen found in the rock. That source could have been the Martian atmosphere, an ancient Martian ocean, or even a comet that struck the planet. There was, then, apparently no mixing system, as on Earth, to blend the two types of oxygen. This was the hypothesis that Gibson’s paper pointed to—no plate tectonics on Mars.