The Rock From Mars (29 page)

Modern Mars, scientists had shown, has no magnetic field.

Within four years, the Kirschvink finding would get a boost from NASA’s Mars Global Surveyor, a robotic orbiter that in this spring of 1997 was well along on a three-hundred-day cruise to the red planet, where it would arrive in September. Once in operation, Surveyor would send back evidence of “remnant anomalies” in the Martian crust indicating that, in its early youth, Mars indeed had a global magnetic field.

“One thing is clear,” Gibson asserted at the time of the meeting. “Any model for a high temperature origin for the carbonate globules is clearly incorrect and invalid.”

Science
magazine would report the data evenly divided between the high- and low-temp camps.

Those Dear Old PAHs

The tongue-twisting hydrocarbons represented a significant find as long as they came from Mars, whether or not they were by-products of living Martians. That was because they suggested an environment that
could have
developed and nourished life on the red planet. But were they from Mars? Jeffrey Bada of Scripps Institution of Oceanography and his coworkers argued that the organic molecules were not from Mars at all but represented contamination from Antarctic meltwater that had flushed through the rock during its 13,000-year entombment. As for the unexpected distribution of the PAHs—denser toward the center of the rock, and concentrated around the carbonate globules—Bada said chemistry, not biology, likely had done that too.

Simon Clemett, of Zarelab, countered that the Scripps experiments were flawed. The challengers, in his view, had failed to distinguish between soluble and insoluble types of the molecules. No other meteorites recovered from the Antarctic ice had the level of PAHs found in the celebrated rock from Allan Hills, and analysis of melted ice from Allan Hills showed no PAHs.

Nanobes We Never Knew

As the McKay team expected, the heaviest counterfire was aimed against those ovoid and tubular, sometimes undulant shapes they had presented as possible nanofossils—remnants of microbial Martians. One prominent microbiologist referred to the shapes as “nanothings.” There were jokes about “no-no-fossils.”

Steele reported that his Portsmouth group had ruled out the argument that the nanoforms had been created in the laboratory when the meteorite sample was coated in preparation for electron microscope viewing. (The shapes were still present when viewed with other techniques.) Others argued that the addition of the coating could enhance an illusion of segmented wormlike shapes that were actually nothing more than angled views of crystal layers and protruding ledges along fracture faces in the rock. (The McKay team would argue in rebuttal that layered minerals are much more orderly and widespread than the possible microfossils, and that they could tell the difference.)

Here, size
was
important. Bill Schopf had argued earlier that the wormy shapes were so small that they had no room for even the barest genetic essentials of a living cell. Romanek calculated that, in terms of relative size, if you could balloon one of the orange carbonate globules (the largest of them barely visible to the human eye) up to the size of a football stadium, the fossil-like shapes would be no bigger than hot dogs.

The McKay team pointed (again) to the work of Robert Folk, at the University of Texas, who had recently published images of what he claimed were fossils of previously unknown Earth bacteria approximately as small as those in the rock. “You can’t tell which are my pictures and the pictures from Mars—they’re absolutely identical in size, textures and shape,” Folk commented in late 1996. He argued that they could be an intermediate form of life somewhere between viruses and bacteria that did not need the same amount of genetic equipment as typical Earth bacteria in order to function. Folk’s interpretations, however, were well nigh as controversial as the work of the McKay team, while the conventional wisdom was all on Bill Schopf’s side.

At least one avid critic concluded that it was the very unprecedented precision and power of their instruments that had led the McKay group astray. In this view, they were like Percival Lowell seeing artificial “canals” on Mars, and like other aggressive, possibly overreaching explorers on any frontier. As if they had suddenly been transformed into insects in their own backyards, they (like everybody else) were seeing this realm for the first time at a scale—millionths of a meter of resolution—so radically small that they could—anyone could—easily misinterpret its unfamiliar warps and rills.

The Mystery Crystals

The magnetic crystals that Kathie Thomas-Keprta had found constituted the strongest—or at least the most intriguing—evidence offered by the McKay team.

Biologists had come to accept perfect, well-organized little formations of grains, or crystals, as persuasive evidence of biological activity on Earth, where certain bacteria were known to produce chains of them. The McKay group had described defect-free, elongated crystals in the Martian specimens that, as far as anyone had yet shown, could be produced only in biological processes.

But variants of the crystals could form without biological activity and were common in ordinary rocks. The peripatetic Ralph Harvey, with colleagues, reported seeing the small, defect-free grains, all right, but also “a zoo of other forms” rampant with defects. These included elongated “whiskers,” which, on Earth, were known to form only around volcanic vents in settings with lethal temperatures of around 650 degrees Celsius. And they included crystals with defects that weighed against their having formed inside the safe haven of an organism, including something called a “screw” dislocation (in which atoms in one row of the crystal matrix were offset), a defect known to occur in crystals grown from vapor but not in those grown inside living cells.

Of all the challenges, McKay was most perplexed by the isotope studies. Because living things on Earth showed a marked preference for the lighter carbon isotope, carbon 12, as they built their cells, the carbon isotopes in the rock, in theory, should have provided a powerful test. But scientists were finding that the carbon signature was muddied and difficult to read. Even more dramatically, the sulfur isotopes seemed to show the clear opposite of the signature expected if Martian microbes had made the selection.

None of these disagreements, per se, troubled the young Dr. Steele. He had flown all the way from England in anticipation of a rational, earnest, dogma-free discussion aimed toward advancing knowledge. Instead, he felt that those on both sides went beyond the scope of the available data to states of unjustified certitude and unnecessary rancor.

As the meeting wore on, he grew increasingly dismayed as he watched seemingly intelligent grown-ups with rhetorical knives and daggers drawn, trying to shout each other down over isotopic ratios and crystal structure.

At one point he finally took the microphone. He rebuked the crowd for “acting like children brawling in a school yard.” He expressed his disappointment. He wanted a consensus, and if there was not yet enough data, he wanted everybody to put their heads together and plan out some experiments that would provide it. He didn’t want to see any more of this chorus of “my ball is bigger than your ball.”

Mary Fae McKay was in the audience. At just about every such meeting she attended, she would pick out someone especially interesting, with whom she’d like to spend time in conversation. About this particular conference, she would say later, “Andy was my ‘find.’ I wasn’t the only person who noticed him, but he stood up several times and made some cogent comments [including] this sort of Rodney King talk at the panel discussion, basically saying, you know, can’t we just all get along?”

Some considered the debate just another useful demonstration of the tug and pull of high-stakes science at its most fervent. Douglas Blanchard, head of the solar system exploration division at Johnson Space Center and straw boss of the McKay regulars, thought it was natural that the process became adversarial. Individual passions about the work helped drive the scientific process. He was one of several in and outside of NASA who believed that the claims about possible signs of life in the Mars rock were generating an “explosion” of learning and new data that would be valuable whether or not the assertion turned out to be correct.

For better or worse, because of the importance of the question and the intensity of modern communications, it was inevitable that these skirmishes would be on display. And one of the few things people on all sides seemed to agree on was this, repeated frequently: “Well, it proves that scientists are human.” It was never the saintly perfection of individual scientists that kept the process honest but the “community” working through the process—the checks and balances of hundreds, sometimes thousands of scientists—operating like some vast organism slumping toward the cheese at the end of the maze.

Still, that process could be painful for those within its coils. Some weeks after this meeting, Zare would issue a statement echoing Steele’s sentiments, decrying the ongoing debate as “emotional and highly disruptive,” as opposed to the skeptical but highly reasoned and dispassionate discourse he had anticipated. The quality of the commentary “has not been terribly impressive,” he said. There seemed to be “a strong element of the blind men and the elephant at work here,” in which “different researchers are looking at different parts of the meteorite and coming up with wildly different reports.”

Like other members of the McKay team, Zare would be dismayed that the constant need to respond to the criticism disrupted his lab research. Zare’s assistant Simon Clemett found himself reacting, working to combat the charges that the organics were mere Earth contamination, when he would rather have moved on to probe the rock for amino acids and other higher-order organic compounds. He got to the point where he was sleepless and depressed.

But here at the March melee in Houston, an astounding thing happened after Steele delivered his sermonette. A man named Gerald Soffen walked up and greeted the bold Brit. Soffen was something approaching a legend in the space program, the man who had led the Viking science team that had carried out the first remote experiments on the surface of Mars. More recently, he had helped Dan Goldin shape NASA’s plan to search for life in the universe.

“I want you to come to work for NASA,” Soffen said. “Come meet Mike Meyer, come meet . . .” And he began to introduce Steele around to NASA officials attending the meeting and to Gibson and others working with the ailing and absent McKay. Steele was stunned—but not too stunned to accept. No matter what bullshit went along with it, he thought, it would be an honor and privilege to be able to do this work.

He soon found himself ensconced in the sanctum sanctorum of the “life on Mars” debate: Building 31. The University of Portsmouth arranged funding for a Ph.D. student to assist Steele. He hired his future brother-in-law, Jan Toporski, an environmental geologist with a sideline in paleontology. They started working under NASA’s auspices in October 1997 and moved shop to Johnson Space Center in November on a two-year postdoctoral grant.

Then a second thing happened to Steele during this already heady period, causing him to develop a serious emotional conflict. Katja Toporski was a captivating anesthesiologist he had met years earlier while working at a hospital in Ireland. Now they were expecting.

Steele moved to Houston alone, leaving Katja at the house they had bought in Portsmouth. He wouldn’t be able to stand it for long. He would end up moving back home in December and staying put until February—feeling guilty but wanting badly to be with his blossoming family.

In December 1997, as he prepared to desert his post for a while and return to England to be with Katja, McKay gave him his second sample of the Allan Hills meteorite and asked him for a reaction. “What do you think that is?” McKay said, pointing to images from the rock samples and forms that to Steele’s practiced eye looked exactly like filamentous bacteria.

This launched Steele, with Toporski, on what would be a pathway that no one before them had followed. Much of what Steele found would be both enlightening and painful for the McKay team.

The Brits would soon determine, unequivocally, that the Allan Hills rock was infested—“teeming like a pig’s ass,” in Steele’s tongue-in-cheek phrase—not with little Martians but
with Earth life.
When he saw the emerging evidence, Steele took a mental stroll through all the published research papers that, by this time, had proclaimed there was “no life” in the rock. Organic contamination, yes, Earth contamination, yes, but “no life.”

Everybody had missed it—until now. Once confirmed, this discovery would be the first documented account of terrestrial microbial activity inside any meteorite recovered from the blue ice fields of the Antarctic.

Steele delivered the news about the infestation to McKay in early 1998. As always, he thought, McKay took the news just the way a scientist should. He was disappointed—but the evidence was what it was.

Everybody on the team agreed that the discovery didn’t eliminate the possibility of Martian biology. The monster challenge would be distinguishing among whatever “pools” of life did exist.

Steele and his coworkers looked at the surfaces of forty chips from the Allan Hills rock, as well as a variety of other Antarctic rock samples. They found that “their” Allan Hills bugs—highly branched, filamentous, with club-shaped endings to some of the branches—resembled the terrestrial actinomycetes bacteria, which had been found previously in Siberian permafrost and in the Antarctic.

The organisms had taken up residence in the outermost portions of the meteorite, near the fusion-crust surface. Steele concluded from this that they were “almost certainly terrestrial in origin” and most likely introduced in the Antarctic rather than in later handling. The bugs were feeding on organics in the rock. It was known that on Earth, the hydrocarbons (PAHs), which could be formed by bacterial decomposition, could also be an energy source for live bacteria. Also, another group had recently shown that the meteorite contained amino acids (organic compounds important to living things).