The Rock From Mars (13 page)

She focused on those little pebbles, or grains, she had noticed earlier, scattered all around but concentrated mainly in the black-and-white rims whose cross section was reminiscent of an Oreo cookie.

They were, she discovered,
magnetic
crystals. And they were quite different from the types she had seen in other space rubble.

Until this point, Thomas had been focusing on technique. She was aiming simply to describe the samples. She had put the notion of Martian biology out of her mind. That now changed.

Reading up on the subject, she learned that there were several possible explanations for the magnetic crystals. One was that they had been manufactured by bacteria. Microbiologists had known since 1975 that certain remarkable swimming bacteria on Earth grew magnetic crystals in their insides. These crystals (whose magnetic properties came from iron atoms) served the bugs as internal navigation devices—compasses. And what Thomas saw in the Mars rock looked a lot like those little compasses.

Keenly aware that they were roaming far beyond their own expertise, McKay and the other collaborators studied the writings of experts in microbiology and the prospects for life on other planets, particularly the burgeoning studies of extremophiles. And they reached for more direct help.

McKay approached Hojatollah Vali, who taught at McGill University in Montreal but happened to be spending a year or two at the Houston space center on a fellowship. The Iranian-born Vali’s specialty was the structure of cells and the minerals formed by living organisms. At McKay’s invitation, Vali examined the samples on the penetrating transmission electron microscope and conceded that the hypothesis was not completely insane: the magnetic minerals
might
have been formed by bacteria.

One night, feeling guilty because her husband was unhappy with her all-consuming work schedule, Thomas was laboring over the rock samples with Vali when they found what appeared to be a second type of magnetic crystal, also similar to those formed inside Earth bugs. They called Dave McKay in to have a look.

The discovery gave Thomas the strong sense that they had nailed the case. She would say later, with a rueful smile, “I can remember walking out to the parking lot that night—it was late, it was pitch-black, my husband was mad at me—and wondering where the bands and the parades were.”

“That’s where she took off,” Romanek would say of Thomas. “She ran with that.”

The magnetic crystals were so small a billion of them would fit on the head of a pin, but they would become arguably the most abiding and intriguing players in the drama of the rock.

One of the things that impressed itself on the collaborators, thanks to Vali, was that the coexistence of this particular menu of iron compounds (iron oxides and iron sulfides) with the carbonates seemed highly unlikely—unless living organisms had intervened to bring them together.

The array surprised Vali. Those magnetic compounds, he told the others, could certainly be found together in nonbiological systems, but then they should have been formed at extremely
high
temperatures. If the carbonates in the rock had been deposited under relatively
mild
temperatures, as Gibson and Romanek had concluded, this particular combination of minerals was difficult to explain. Also, these compounds would not ordinarily form out of the same type of solution that produced carbonates. It all seemed a little like stumbling across a ski slope in Florida in August, not knowing that some eccentric amusement park entrepreneur had gone to considerable lengths to manipulate the environment for profit.

Scientists historically have favored the elegance of simplicity. They have tried to avoid contorted reasoning, twisted and bent to fit a preconceived notion. The McKay group figured that, although there were certainly alternative possibilities, the odd confluence of the lines of evidence they were finding in the Mars rock could be explained most simply by the presence of living things. Others would interpret the same set of facts differently.

McKay and his team knew that biology flourishes along the boundaries where contrasting environments meet. Living things find ways to harness these “edge” contrasts to their benefit. The human stomach, for example, is home to billions of bacteria that would die if exposed to the outside air breathed by the stomach’s owner. Terrestrial life had shown itself to be uniquely capable of manipulating its environment, and the same could be true of some primitive, long-extinct species of Martian.

At the same time, however, the McKay group was taking care to study the alternative story lines that would explain what they saw without resorting to Martian biology. Well aware of the risks of embarrassment and ridicule they could face when or if they went public, McKay and Gibson were painstaking about this sort of double-checking.

What they did next would provide fodder later on for one of the most bitter and personal feuds that would arise out of the investigation. The McKay team turned for help to a man widely recognized as a supreme authority on ancient microfossils: Bill Schopf, of UCLA. Gibson called and invited him to come down and take a look at their evidence; they arranged for their department to pay his way.

Schopf had rewritten the textbooks on the origins of life on Earth by claiming discovery of the oldest fossils known—the remains of microbes 3.465 billion years old. His memory of his visit to Houston would differ from that of the McKay group, beginning with who issued the invitation. (Schopf would later state that the call had come from “NASA administrators.”)

Romanek was given the responsibility of putting together a presentation for the prominent visitor. He got busy arranging for the graphics and data that would enable Schopf to understand quickly all that the collaborators had seen in the rock. They wanted to leave plenty of time for Schopf to put some thin sections under a microscope and see for himself, and then for them to sit and discuss the whole matter in detail. Romanek prepared foam-backed poster boards and glued all the team’s microscope images onto them, showing the textures and fabrics they had found in the meteorite, with the sizes of the features in the carbonate indicated.

When Schopf arrived at the space center on January 24, 1995, he found the researchers “flushed with excitement.” They met in David McKay’s office. The mood was cordial, by all accounts. The group laid out the posters; then Schopf looked at thin sections and chips from the rock.

The group had sworn Schopf to secrecy, and he would be true to his word. But when they took him to the meteorite archives, Robbie Score was there. She had studied under Schopf at UCLA and “put two and two together,” as Gibson would recall. The group asked her to keep her surmise to herself.

Romanek would later remark that, as Schopf inspected a thin section under the microscope, “he pulled his eyes back and looked kind of shocked. But one second after that, like a true scientist, he was thinking, ‘How can I explain this by anything except what you’re telling me you think it is.’ ” In the end, Schopf pronounced the fossil-like features “very interesting” but the evidence far from convincing.

Schopf told them, “You’ve got some real interesting stuff there, but you’re not going to go anywhere with this until you can show me organic matter in the structures.” Schopf’s view was that they had to find organic matter to suggest any kind of fossil at all. And they must show varying shapes and sizes, presumably representing juvenile and adult phases of growth.

Schopf would write later that the Houston group had suggested that the carbonate globules, with their black-and-white rims, resembled the disk-shaped shells of a particular type of protozoan (one-celled organism) and might be a fossilized Martian version. (The McKay group would deny that they had said or thought that. Romanek could not recall ever having heard the term in that context. McKay and Gibson said that, in an effort to take full advantage of Schopf’s expertise and to overlook no possibility, they had asked if certain features in the rock could be protozoan
-like—
just to rule it out.)

Schopf told them they were wrong, that the size range did not fit biology, and that the objects lacked telltale features—“pores, tubules, wall layers, spines, chambers and internal structures—that earmark tiny protozoan shells.”

Gibson and his wife drove Schopf back to the airport at the end of his two-day stay. As they dropped him off, they were struck by a comment he made: “Today I saw enough interesting structure and other things indicating possible biology in those thin sections that, if it was early in my career, I would choose to spend more time on this rock.”

That same day, Gibson asked his wife, a biologist, to sit down and write an account of what Schopf had said. Gibson and McKay also wrote a memo summarizing their discussions with Schopf—part of an ongoing record of dates and developments in the project that Gibson, as the group’s unofficial recording secretary and historian, was keeping.

Schopf’s most disheartening point, Romanek thought, was that the McKay group would never convince anybody that these mineral structures were of biological origin unless they could find complex organic material associated with them—something like a remnant of bug slime, products of cell decay, or other recognizable biological signature. “I’m thinking, well, I could argue with Bill that there was organic matter there and it was oxidized,” Romanek would say later. “But that was a very big letdown . . . because we ‘knew’ there was no organic matter on Mars.” Many people “knew” this, based on those Viking experiments that had helped exile E.T. and paved the way for the rise of the dreaded giggle factor.

Even if their instincts were right, the McKay team realized that their punch line lacked a proper buildup. For a claim to be at least provocative, if not persuasive, it had to include a chronological narrative that provided context into which individual clues fit and made sense. There had to be a plausible
story.

Romanek feared that the project was at a dead end.

But Kathie Thomas, for one, was not about to give up so easily. In the coming days, she would summon up a troop of California cavalry to ride in and save the day—laser cowboys from the wild west of Silicon Valley.

CHAPTER SIX

MICKEY, MINNIE, AND GOOFY

I
N LATE
1994 and early 1995, as David McKay and his collaborators puzzled over the Mars rock, Richard Zare, fifty-six, reigned as master of the eponymous Zarelab. The complex, with twenty-five researchers, was housed in a corner of the palmy, well-trimmed campus of Stanford University, in the heart of Silicon Valley.

A world-renowned laser chemist—a “towering figure in the field of chemical physics,” in the words of a Harvard Nobel laureate—Zare was known for devising ways to watch how molecules “dance,” break apart, and recombine in chemical reactions. He had developed various practical tools and acquired almost fifty patents. He seemed on track to receive his own Nobel.

Zare had never been a Trekkie, a space cowboy, or a stargazer. Growing up in Cleveland, he’d thought that just finding the Big Dipper was enough of an accomplishment. So he was naturally amused when a close brush with a chunk of Mars turned out to be the thing that brought him his first Warhol moment. As he would write later, that tiny piece of Mars “fell into my life, and changed it forever.”

Zare looked Mephistophelian, with his heavy, dark eyebrows and salt-and-pepper mustache and goatee. And he was driven—an overachiever, haunted by a painful childhood and a memory from when he was four years old of his grandmother telling him he was “going to be judged.” He thought it somehow had to do with being Jewish, and representing his people well.

But a wicked grin softened the edges of his intensity. As a professor of chemistry, Zare carried to class his boyish sense of mischief. He had enlightened generations with his glowing-kosher-pickle routine—a demonstration that sodium could be used to generate light.
Physics Today
had devoted a cover story to his learned thoughts on beer foam.

Zare was also what he laughingly called a “big shot.” Gifted at navigating the treacherous political waters of Washington, he was the head of the National Science Board, which set policy for the National Science Foundation. (The foundation is a primary dispenser of funding for American scientific research, including the meteorite hunt and other Antarctic programs.)

A few years earlier, a fateful late-night encounter had changed Zare’s attitude toward the cosmos and put him on course for his liaison with the McKay team and the secret project. He had worked so late that, as he walked home from his lab, he saw not a single car moving on the usually busy campus streets. Overhead, he watched the eucalyptus leaves tremble in a breath of wind and smelled a trace of their dusky scent. The air was so clear that the stars shone as if they’d been scrubbed and polished for some special occasion. He heard footsteps, and another solitary walker crossed to his side of the road. They fell in step and started chatting, telling each other about their work. The other man, it turned out, was a meteorite specialist named Peter Buseck, visiting from Arizona, who began describing to Zare the chemical messages contained in the rocks that fall from space.

Zare told Buseck he was intrigued. In his lab was an instrument that he was certain could help decipher those messages. He felt a powerful inclination to tackle the problem, even though he knew nothing about meteorites. (It had always been his tendency to ignore the arbitrary boundaries and labels that separated one scientific specialty from the next. They blocked creativity.) As usually happened when his mind was seduced by such a dare, the sensation on this occasion was almost physical, like a buzz in his head.

Early in his career, Zare had invented a laser device that could coax out the identity of a chemical substance even when only a few molecules of it were present. After his epiphany under the stars, he and his graduate students and postdocs started using the technique to poke around in meteorites.

One of his grad students, an industrious Englishman named Simon Clemett, grew particularly enthusiastic about the work. The experiments he developed worked so well that soon far-flung researchers were sending the Zarelab samples of meteorites, interplanetary dust, and other “cosmic schmutz.”

Among those who had been shipping space droppings to Zarelab was Kathie Thomas, initially as part of her work on McKay’s cosmic dust project. The Houston lab sent Zare samples not only of dust but also, for purposes of comparison, of meteorites from asteroids and in some cases from Mars. The people at Zarelab learned that only ten or so of the thousands of meteorites collected to date—the SNCs—bore the unique characteristics of Mars.

Thomas enjoyed her liaison with Zarelab. She and Clemett became friends. In the gloomy wake of Schopf’s visit in January 1995, Thomas told her collaborators in Building 31 that she intended to call up her buddy Simon in California. “Let’s just see if there are organics associated with this meteorite.”

Romanek and Thomas had already sent Zarelab samples of the rock a couple of months earlier by Federal Express. The package carried sealed containers with two tiny chips of the rock (one about .08 inch, or 2 millimeters across, the other about .04 inch, or 1 millimeter).

But in keeping with their vow of secrecy, and in order to avoid any chance of prejudicing the results, Thomas and Romanek had not told Zarelab that the material was Martian. They referred to the chips instead by the code names Mickey and Minnie.

Accompanying the samples was a letter addressed to Clemett. It included crude, hand-drawn maps of Mickie and Minnie with instructions. “Minnie has a smooth face without any blemishes except for one prominent orange structure on the surface which is almost round. . . . If you can target the orange bleb . . . separately, that would be great.” It went on, “When you have finished with Minnie move on to Mickey. He is much more complex but also more interesting.” The letter concluded: “Good hunting!”

Clemett found the whole thing a little weird. In fact, the lab’s interest in the chips, at first, “hovered between zero and negative some number.” Mickey and Minnie sat on a shelf for months.

Now Kathie Thomas’s pleas grew pointed and urgent. “We want you to look at these real bad. Real bad, okay?”

Clemett finally went ahead and did the analysis. Like Kathie Thomas before him, he considered these samples, tiny as they were, to be giant boulders compared to the incredibly minute specks he was accustomed to studying.

The Zarelab technique was revolutionary and dramatic—a combination shooting gallery and Pachinko machine. Clemett called it “chemistry without the chemicals.” Chemists traditionally had to grind their samples to powder, or assault them with chemicals. Zarelab’s technique harnessed laser beams to replace liquid solvents. This enabled Clemett and his coworkers to examine certain features in their native setting, detect much smaller traces, and eliminate much of the danger of contamination.

In simple terms, the device—a laser mass spectrometer, the most sensitive instrument of its type in the world—shot a laser beam at a precisely chosen target the size of a pencil dot on the rock sample, which sat in a vacuum chamber containing an electric field. The first beam heated the target at a rate of about 100 million degrees per second, but for only ten-millionths of a second—so rapidly that the molecules poofed, undamaged, into a cloud of vapor.

When Clemett pushed a button, the second beam—an ultraviolet laser that could punch a hole in human skin—stabbed across the cluttered lab unshielded (as he sat very still, careful not to expose an arm or other body part) and through the rising gas plume. This beam was sixty times brighter than the first but fired for only one-billionth of a second, giving selected types of molecules a positive charge by ripping off an electron. In a split second, the positively charged molecules accelerated into a negatively charged plate five feet away, the smaller ones outsprinting the fatter ones. By measuring the time of flight, the team could identify the molecules by their mass.

The laser technique could reveal details at much smaller scales than any system yet brought to bear on the rock—features so small they could be as hard for the human mind to grasp as the diameter of the entire universe. The team was analyzing down to billionths of a part per billion. (The McKay group in Houston referred to the Zarelab equipment as “the best gun in the west.”)

The Houston team asked Zarelab to zap, and map, the mystery rock, moving from the outer skin (with the blackened fusion crust) down into the interior, including an area where one of these orangey globs was embedded.

Zarelab sent the results to Houston.

Kathie Thomas phoned Zare back, sounding very excited. “Richard, please drop everything else you’re doing,” she said. “We just FedExed you another sample from the same rock, this one code-named Goofy. I know it’s asking a lot, but we need your analysis ASAP.”

Zare balked. “You can call your rocks anything you want, but we’re not analyzing any more of them until you tell me what the fuss is all about. What’s going on?”

Thomas hesitated. If the new results hold up, she told him, “You have found the first known organics from Mars.”

Then she said, “The fragments are from ALH-eight-four-zero-zero-one, a meteorite found in Antarctica a decade ago. We are confident the meteorite originated on Mars.” Of the other known meteorites from Mars—by now there were twelve—this one was by far the oldest and contained a record from a time when the red planet was relatively wet and warm.

Another pause. She took a breath, and said, “We think the meteorite may contain evidence of life.”

Zare froze momentarily, wondering if he might not be dealing with a nutcase here. But he was not completely shocked. Based on the nature of the evidence they were finding, he and Clemett had begun to suspect that this interstate dialogue might be pointing toward a biological signature—one from inside what they presumed to be some kind of space rock. Still, when Zare heard Kathie yoke together the words “Mars” and “life,” he felt a chill run all the way down to his ankles. He listened as Thomas went on to tell him that her group had already identified some features in the rock that they suspected might be fossilized traces of ancient bacteria.

Now the Zarelab results had supplied a whole new line of evidence that greatly bolstered the case. No wonder the folks in Houston were excited, Zare thought. So was he! He ran up the stairs to the lab to tell Simon the news, but as he ran, he sensed little red flags sprouting up around the edges of his enthusiasm. This instinct kept him from getting completely swept away.

Zare knew that most people regard scientists as resolute skeptics. That was only half right, in his view. To be really good, you had to have a split psyche, had to believe in your work at every step while at the same time never believing in it at all. A complete skeptic would be terrified of taking a chance on anything short of a sure thing while, on the other hand, belief unfettered by doubt would leave you in dire peril of fooling
yourself—
a cardinal failing. Zare believed it wouldn’t do for him to arm himself with just a small shot of skepticism, or a smidgen of belief. You needed both going full blast all the time.

As a boy, Zare would read under the covers with a flashlight—about chemistry. By age nine, he was catching buses to the library, alone, to read and play chess. In junior high, he challenged an inexperienced teacher who claimed to know “facts” that Zare understood were actually still matters for debate. The principal, desperate for relief from this upstart, arranged a scholarship to a nearby private school, where Zare blossomed.

By the age of twenty-four, the precocious student had a Ph.D. from Harvard. While there, he gravitated toward bold thinkers, joining a laboratory that was known at the time as “the lunatic fringe.” (Zare’s mentor there later won the Nobel Prize.) Zare worked at MIT, the University of Colorado, and Columbia before the West Coast lured him in 1977.

Now (in keeping with his rule of split-psyche zeal), having found possible evidence of the first sign of life beyond Earth, Zare put his team to work trying to prove that they had found nothing of the kind.

They had to check for the familiar villain, contamination. Mickey, Minnie, and Goofy had been transported around Building 31 from the upstairs curatorial lab, and had sat in little vials before they went to Zarelab. Because organic molecules are everywhere on Earth, it was possible the samples had gotten contaminated along the way—despite all precautions.

Back in Houston, the McKay group was humming with adrenaline, a blend of tension and excitement. When they had sent the samples off to the Zarelab, they’d expected that if there was any significant organic stuff to be found, it would be most abundant close to the rock’s surface, because the organics would have penetrated inward from Earth’s atmosphere or oozed in from the Antarctic ice melt as terrestrial contamination. They felt pretty sure that any such readings would decrease going in toward the heart of the rock.

They were stunned by the Zarelab results. Not only were organic compounds (molecules with a crucial carbon-hydrogen bond) present in the rock, but their distribution was the reverse of what the team expected. Simon Clemett and other Zarelab workers found the organics to be sparse on the rock’s surface, but as they penetrated its interior, they found an increase in the abundance of organic molecules whenever they came across a carbonate moon. As they pushed past the carbonate, the abundance would go down again.

Zarelab produced a map of the rock’s geography, showing that the organic molecules were concentrated in “hot spots” around the carbonate moons, in the regions where the magnetic crystals and other suggestive features were also thickest. This was consistent with the notion that the organics were by-products of a fossilization process, whispers of long-dead Martians.

It was this spatial relationship between the organics and the carbonate moons that gave the Houston team goose bumps.

What were these organic molecules? The team members knew they were greasy hydrocarbons of a type found on Earth wherever life has existed. Called PAHs (polycyclic aromatic hydrocarbons), they could be formed by a variety of biological processes, like the ones that form petroleum and coals. They were part of the yummy black residue on a burnt steak. Most typically, they were the product of cellular decay.