Discovery 
A Beautiful Mind 
It Came From Outer Space
When scientists at the Johnson Space Center thought they had found signs of life in a Martian rock, it was good news for NASA, Bill Clinton, Hollywood, the tabloids–and even Dick Morris’ favorite call girl.
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What the two men saw that day was something strange—tiny orange-brown patches that, to the naked but well-trained eye, resembled bits of carbonates. On Earth, carbonates include marble, limestone, and other materials formed near water. Scientists had long suspected that Mars once had water because of its topography—dried-up riverbeds and deltas, for instance—but they never had a way to prove it. Carbonates had never been found there, nor had anyone found such traces in NASA’s other Mars rocks; they were billions of years younger, after all, and had come from the period in which the planet’s water had already disappeared. Romanek allowed himself a momentary fantasy. Maybe these carbonate globules, as he and Mittlefehldt called them, had been formed when water flowed through cracks in the rock, leaving tiny deposits behind. Maybe, with the right tests, the rock could be made to reveal its past.
Once Mittlefehldt and Romanek satisfied themselves that the brown spots were indeed bits of carbonate and that they were indeed Martian—the carbonates were dated at 3.6 billion years, which meant they had been formed long before the rock left Mars—the scientists wanted to determine the temperature at which they had been formed. They teamed up with Romanek’s mentor, another NASA scientist by the name of Everett Gibson, an expert in meteorites. Gibson, 53, was paunchy and mustachioed, a man who seemed constantly amused by the humor of whatever situation he found himself in. This project, however, was no joke. The researchers wanted to investigate the chemical, or isotopic, attributes that would reveal the temperature at which these carbonates had been formed. With the help of some British scientists, they ran the numbers, and the results left them astonished: The carbonate globules had been formed at somewhere between 0 and 100 degrees Celsius, temperatures similar to those found on the surface of Earth—temperatures, though no one would say it out loud, capable of sustaining life.
In 1992 Romanek had attended a lecture by a University of Texas sedimentologist named Robert Folk, who had discovered tiny fossils in pieces of limestone, fossils far smaller than had been seen before—some as small as one one-thousandth of the width of a human hair. Other researchers had discovered not only that life could exist at a much smaller size than had been previously imagined but also that it is far more tenacious, thriving, for example, in boiling-hot vents at the bottom of the ocean. These were the discoveries that were galvanizing the scientific community. Now Romanek wondered: Since the temperatures on Earth and Mars had once been similar, could the same kind of tiny fossils found in limestone—that is, evidence of life—be hiding in the orange-brown patches dotting the interior of the Martian rock?
WORKING ON HIS OWN, DAVID MCKAY had been thinking along similar lines. He estimated that he had looked at more than 50,000 rocks in his life, and all he would allow himself to say about this one was that it was “suspicious” or “interesting.” In between his inspections of lunar dust, he would drag out his Mars slides, losing himself for hours in the caves and canyons of the rock as revealed by a microscope. Like a sixteenth-century explorer, McKay had encountered a new world, as vast as it was infinitesimal. But instead of a wooden ship, he navigated a scanning electron microscope (SEM), which magnifies up to 30,000 times. What intrigued McKay in particular were tubular shapes—masses of them, sometimes—that he had never seen before. They might have once been bits of clay, but they might also have once been bits of organic matter. For the moment, he had no way of knowing.
In the summer of 1994, Chris Romanek and Everett Gibson appeared in McKay’s office. McKay knew Gibson well, of course; they were contemporaries and had worked on the moon rocks together. Where McKay was taciturn and cautious, Gibson, who sometimes spoke of himself in the third person, was loquacious and adventurous. What he and Romanek proposed was consistent with his character.
They wanted to start searching for fossils in the Martian meteorite’s carbonate globules. Romanek explained that he had already made sections of the rock and was viewing them on the SEM. But he had worked on the SEM for only a year, and Gibson admitted that he too lacked expertise in interpreting the images the machine produced. They had come to McKay, Gibson said, because he had the experience in microscopy they needed. McKay looked at their pictures slowly, and then he looked at them again. What he saw were the same tubes he had seen before, structures that seemed frustratingly beyond the scope of recognition. Yes, McKay agreed, these were worthy of additional work. That day, the three men made two decisions: They would work together as a team—and they wouldn’t tell anyone else what they were doing. People would think they were nuts. Or worse, they might try to steal their idea.
BUT THEY NEEDED SOMEONE ELSE. Kathie Thomas-Keprta, McKay’s colleague of twelve years, had expertise with a different kind of microscope: the transmission electron microscope, or TEM. While the SEM could explore only surfaces, the recently developed TEM could pass an electron beam through the carbonates and reveal their mineral composition, in turn possibly unlocking more of the rock’s secrets. (By way of analogy, a scientist trying to identify a loaf of bread would use the SEM to examine the crust and the TEM to reveal sugar and salt crystals.)
The only problem was Thomas-Keprta herself. The blond, willowy scientist was 37 and an authority in the esoteric arena of cosmic dust, which is a by-product of comets and asteroids. Once, a person of her talents would have been working for NASA full time, but she was classified as contract help—a glorified temp—on loan from Lockheed-Martin. Weary of having to justify the significance of her research, Thomas-Keprta was ready for a change. But that didn’t mean she wanted to embarrass herself before the entire scientific community. “We have a project that needs your talents,” McKay began after escorting her to his office. With Gibson present, he asked whether Thomas-Keprta would be interested in taking a closer look at the carbonates in the Martian meteorite. They showed her their strange SEM pictures. They suggested, gently, that she would be looking for, well, fossils. Thomas-Keprta looked from McKay to Gibson and back again. Were they serious? “Oh, no,” she told them. She was much too busy. That night she went home and told her husband, “These guys are nuts.” But McKay was her boss, and along with Gibson, he was feeding her samples to examine. She began to find that more and more of her time was taken up in the darkened room with the enormous microscope, exploring the grains on the edges of the rock’s tiny orange-brown carbonates without knowing where she was headed or what, exactly, she was looking for.
THOUGH NO ONE WOULD SAY SO, they thought they might be getting close to finding signs of life by the winter of 1994. They had water, they had hospitable temperatures, and they had microscopic pictures they thought were intriguing if not conclusive. But as planetary scientists and NASA survivors, they knew they couldn’t go public without getting the blessing of a real expert in the field they had now entered, the world of microfossils. They chose an acquaintance and colleague of Gibson’s, paleobiologist William Schopf at the University of California at Los Angeles, a writer of textbooks, winner of prizes, and the current authority on microfossils. Schopf had to be coaxed into taking the trip to Clear Lake. Gibson told him only that they had found some unusual structures in a meteorite; he was careful, in fact, to avoid the phrase “life on Mars.” Schopf came, looked at a few pictures, and shrugged his shoulders. He didn’t see anything that suggested signs of life. What did he need? they asked. Schopf was polite but firm: The scientific community had standards for proving such a hypothesis. McKay’s team knew where the rock was from, and they knew that the carbonates were about a billion years younger than the rock. But now, Schopf told them, they had to produce evidence of cells and their by-products. Without such proof, they would never get their work published. “It was,” said McKay with typical reserve, “a setback.”
It wasn’t enough to have found carbonates within the rock; now they had to examine the molecules within the carbonates. Carbon, as every schoolchild learns, is the building block of living things. But it is also found in countless inorganic substances. If their rock was composed solely of inorganic substances, the game was over. Worse, the JSC team lacked the technology to analyze molecular structures themselves—NASA’s days as a technical giant were long gone. There was only one place in the country with the expertise to handle this problem, and that was the laboratory of Stanford chemistry professor Richard Zare, who in 1985 had developed a “laser shooting gallery” that could analyze single molecules. Fortunately, Thomas-Keprta had a friend who worked for Zare. She chipped off a few more pieces of the rock and sent them to Stanford. Once they arrived, the chips were bombarded with two kinds of lasers; the scientists then captured the gas emissions and analyzed the results. As if to order, the Stanford scientists—who quickly joined the team—found just what McKay’s group had hoped for: polycyclic aromatic hydrocarbons, or PAHs. For a few minutes, the JSC team allowed themselves to be jubilant. PAHs often arise from the decomposition of living matter. Then they admitted the truth to themselves: PAHs can also arise from inorganic substances like truck exhaust or air pollution. They had to be sure that the sample had not been contaminated at the JSC lab and that the PAHs had not come from snowmobile exhaust in Antarctica. More tests were run, and once again the results were exhilarating. PAHs that arise from pollution tend to cluster on or near the surface; the Mars rock’s PAHs were 500 microns below the surface—far enough inside the rock to have predated snowmobiles by billions of years. These PAHs had to be indigenous to the planet Mars.
The team was so excited that they drafted a paper for presentation at the next Lunar and Planetary Science Conference, in March 1995. They didn’t say they had found life on Mars; they said they had found PAHs on Mars. A Houston Chronicle reporter, however, understood the significance of the discovery and cornered Thomas-Keprta after she presented the paper in Clear Lake. Are you saying, the reporter asked, that there is life on Mars? “No,” Thomas-Keprta replied. “Absolutely not.”
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