The Rock From Mars (46 page)

CHAPTER FIVE:
the convert

She was at work
• Accounts in this chapter rely primarily on the author’s interviews with McKay, Gibson, Romanek, and Thomas, and an e-mail exchange with Dennis Bazylinski, a specialist in magnet-making bacteria.

Her analysis held up
• See K. L. Thomas, B. E. Blanford, C. S. Clemett, G. J. Flynn, L. P. Keller, W. Klock, C. R. Maechling, D. S. McKay, S. Messenger, A. O. Nier, D. J. Schlutter, S. R. Sutton, J. L. Warren, and R. N. Zare, “An Asteroidal Breccia: The Anatomy of a Cluster IDP,”
Geochimica et Cosmochimica Acta,
vol. 59 (1995), pp. 2797–2815.

She would run into
• E-mail from Thomas-Keprta to author, April 21, 2005.

Microbiologists had known
• The magnetic crystals Thomas detected in the rock had about the right size (40 to 50 nanometers), the right shapes (roughly cubical or teardrop), and the right chemistry, in the McKay group’s view, to have been made by living organisms.

On Earth,
magnetotactic bacteria
churn out a line of nearly identical little magnets—virtually flawless compass needles. The microbes use them to navigate up and down through the water column to find food. These biomagnets derive their power from their iron atoms. (Such minerals typically are compounds of iron and something else, usually oxygen or sulfur.) These bacteria manufacture either magnetite (iron and oxygen) or greigite (iron and sulfur). What Thomas and the others found in the Mars rock were both kinds—iron oxides and iron sulfides.

For early descriptions of magnetite-producing bacteria, see S. Mann et al., “Structure, Morphology and Crystal Growth of Bacterial Magnetite,”
Nature,
vol. 310 (1984), pp. 405–7. For a review on the magnetotactic bacteria see D. A. Bazylinski and R. B. Frankel, “Magnetosome Formation in Prokaryotes,”
Nature Reviews in Microbiology
, vol. 2 (2004), pp. 217–30.

Keenly aware that
• Author interviews with McKay and colleagues. See also Michael Ray Taylor,
Dark Life
(New York: Scribner, 1999), pp. 94–95. Among the experts whose published writings the team consulted were Chris McKay, Jack Farmer, and Michael Carr, on exobiology (a field soon to be expanded under the term
astrobiology
); Imre Friedmann on microbial communities in Antarctic rocks and the Sinai Desert; Henry Chafetz on bacteria in carbonates; Carl Woese and Norm Pace on genetic studies of ancient microbes; Thomas Gold’s
The Deep Hot Biosphere
(New York: Copernicus, 1998); James McKinley and Todd Stevens, on microorganisms extracted from deep drill holes in Washington State’s Columbia River basalt; and E. Olavi Kajander, on (claimed but controversial) nanobacteria in blood.

McKay approached Hojatollah Vali
• Author interview with Vali. The National Research Council funded his fellowship.

One night, feeling guilty
• The first type was magnetite—iron combined with oxygen. This kind appeared to be iron with sulfur—greigite.

The array surprised
• Aside from the temperature questions, the presence of
carbonates
implied that the native solution from which the magnetic crystals formed was one of low acidity (alkaline). The presence of the minerals found
inside
the carbonates, by contrast, implied an acidic solution. Ordinarily, the iron oxide crystals (magnetite) would require an oxidizing environment, while the iron sulfide (greigite) would need the opposite, a reducing environment. Vali told the author that seeing these two types of crystal together raised the suspicion that biology might have been involved as a mediator.

McKay and his team
• Author interviews with the team. See also Donald Goldsmith,
The Hunt for Life on Mars
(New York: Dutton/Penguin, 1997), p. 81.

At the same time
• The McKay group studied papers published by others who argued that the key features in the rock had formed at temperatures too high for life. The McKay group reinvestigated and concluded the high-temperature arguments could not be right. The numbers didn’t fit the profile, so to speak. They compared the data to high-temperature “phase diagrams” worked out earlier by Eric Essene at the University of Minnesota. The McKay group stuck by its low-temperature scenario.

Gibson called and invited
• Author interviews with Gibson.

(Schopf would later
• J. William Schopf,
Cradle of Life
(Princeton, N.J.: Princeton University Press, 1999), p. 304. In an e-mail to the author, May 6, 2005, Schopf clarified, saying that NASA’s chief exobiologist Michael Meyer had called him first. “Only after he asked me to go to JSC did folks from there call me,” Schopf said.

When Schopf arrived
• Ibid., p. 304.

The group had sworn
• Author interview with Gibson; e-mail to author from Schopf.

Romanek would later remark
• Author interview with Romanek.

Schopf told them
• E-mail from Schopf to author. Author interview with Gibson.

Schopf would write
• Schopf,
Cradle of Life,
p. 304.

Schopf’s most disheartening
• Author interview with Romanek.

CHAPTER SIX:
mickey, minnie, and goofy

In late 1994 and
• Author interviews with Zare were a primary source of material for this chapter (except for assurances of his influence and achievements, which came from his colleagues, officials at the National Science Foundation, NASA, and others). In addition, Zare supplied in writing his impressions of events related to the Mars rock. Some descriptions came from a magazine feature on Zare (James Shreeve, “The Light on Life,”
Discover
[May 1997]: pp. 50–55), as well as from material supplied by Stanford, and from author interviews with associates of Zare’s, including David Salisbury and Simon Clemett.

A world-renowned laser
• The “towering figure” quote is from Nobel laureate Dudley Herschbach, of Harvard, under whom Zare studied for his graduate degree. (See Janet Basu, “Fourth Rock from the Sun,”
Stanford Today,
Nov.–Dec. 1996.)

Zare had never
• Zare’s unpublished written account.

He had enlightened
•
Stanford Today,
Nov.–Dec. 1996.

A few years earlier
• Zare’s written account; see also James Shreeve, “The Light on Life,” pp. 50–55.

One of his grad
• Author interviews with Zare and Clemett; Zare’s written account.

Among those who
• Author interviews with McKay, Thomas, and Romanek.

Thomas enjoyed her
• Interviews with Thomas and Romanek.

Romanek and Thomas had
• Letter, with hand-drawn sketches of the samples, sent by Romanek and Thomas to Simon Clemett at Zarelab, November 18, 1994. The letter accompanied the sample shipment.

Clemett found the whole
• Author interviews with Zare and Clemett.

The Zarelab technique
• Zare worked on the technique initially with colleagues Yan Kuhn Hahn and Renato Zenobi.

Clemett called it “chemistry
• Author interview with Clemett; quote also cited in Donald Goldsmith,
The Hunt for Life on Mars
(New York: Dutton/Penguin, 1997), p. 84.

In simple terms
• Author interviews with Zare and Clemett, and written descriptions from them and from David Salisbury (then at Stanford News Service). The device adapted for the meteorite samples was the Microprobe Two-Step Laser Mass Spectrometer, sometimes called by the even knottier monicker Two-Step Laser Desorption Ionization Time-of-Flight Mass Spectrometer. The effect of the instrument’s heat flash was to remove the whole target molecule intact, before the chemical bonds could break, and convert the molecule directly into gaseous form. (Nobody understood why this worked so well, Zare said.)

Then the second beam fired. The beam knocked electrons off a designated class of molecules, giving them an electrical charge. By creating an electric field within the vacuum chamber, the researchers could accelerate the selected molecules to velocities approaching a hundred miles per second—into a wall. A detector measured the travel times, enabling the researchers to then “weigh” the mass of each molecule. (The shorter the flight time, the lighter the molecular mass.) They would end up with a kind of census of the molecule types by weight. The ultraviolet laser could be tuned to pick out selected families of organic molecules: amino acids, DNA bases, or PAHs. Combining this selectivity with the mass measurements, the researchers could very accurately determine the relative abundance of various organic compounds.

The technique’s unprecedented sensitivity posed a problem. At first, it tended to “sample itself,” as Clemett put it. It measured minute amounts of pump oil, fingerprints, and other organic contaminants in the instrument itself. After much effort, the team developed ways of eliminating potential sources of contamination.

When Clemett pushed
• Clemett demonstrated the device for the author. Clemett worked on the Mars meteorite with postdoctoral fellows Xavier Chillier and Claude Maechling.

Kathie Thomas phoned
• Author interviews with Thomas, Romanek, Zare, and Clemett.

Zare froze momentarily
• Zare’s written account; author interview with Zare.

As a boy, Zare
• Author interviews with Zare, Zare’s written account; see also Shreeve, “The Light on Life,” pp. 50–55.

By the age of twenty-four
•
Stanford Today,
Nov.–Dec. 1996; Zare earned his graduate degree in the lab of Dudley Herschbach, who with two others won the Nobel Prize for chemistry.

It was this spatial
• Author interviews with McKay and other team members.

The investigators also
• Author interview with Clemett; see also Goldsmith,
The Hunt for Life on Mars,
pp. 88–90. Chemically, PAHs (polycyclic aromatic hydrocarbons) are made up of hydrogen and carbon atoms, arranged in structures called benzene rings. They have the distinctive odor associated with the colorless and highly flammable liquid called benzene (which is derived from coal and used as a solvent). Benzene rings are a popular favorite among all known forms of life. In fact, the field of organic chemistry is essentially the study of such ring-shaped carbon compounds. Living things exploit carbon’s friendly chemical handshake—its unique ability to form large, complex molecules in which other elements are bonded to its atoms.

They caught up with
• Michael Meyer interview with Steven J. Dick, NASA archives. Regarding exobiology and NASA, see Steven J. Dick,
The Biological Universe
(Cambridge: Cambridge University Press, 1996), pp. 356, 477–78. In the 1960s, NASA had started funneling modest funds to exobiology studies because of the agency’s decision to search for life on Mars. The work, concentrated at its Ames Research Center in California, was heavily oriented toward research on the origins of life.

In their presentation
• Author interviews and e-mail exchanges with Kathie Thomas. She said, “I regret that Simon [Clemett] is not the first author” on the paper reporting the first significant Martian organics: K. L. Thomas, C. S. Romanek, S. J. Clemett, E. K. Gibson, D. S. McKay, C. R. Maechling and R. N. Zare, “Preliminary Analysis of Polycyclic Aromatic Hydrocarbons in the Martian Meteorite (SNC) ALH84001,” (abstract),
Lunar and Planetary Science Conference,
vol. 26 (1995), pp. 1409–1410.

The reaction was
• Vincent Kiernan, “The Mars Meteorite: A Case Study in Controls on Dissemination of Science News,”
Public Understanding of Science
9 (2000): pp. 21–22; Kiernan cites R. Cowen, “Mars Meteorite Poses Puzzling Questions,”
Science News
(March 25, 1995): p. 180; “A Chip Off the Old Mars,”
Sky and Telescope
(July 1995): p. 12; C. Byars, “Mars Meteorite Contains Carbon Compounds,”
Houston Chronicle,
March 18, 1995, p. A34; and K. Davidson, “Meteorite May Hold Secret That There Was Life on Mars,”
San Francisco Examiner,
March 16, 1995, p. A4. Everett Gibson, in an interview with the author, credited the
Chronicle
’s Byars with being the first reporter to hint that the group might be thinking in terms of possible Martian biology, based on his coverage of this meeting.

They seemed to be
• Author interviews with McKay and Zare. See also Goldsmith,
Hunt for Life on Mars,
p. 114. The composition of the PAHs in the meteorite was consistent with what the scientists would expect from the fossilization of very primitive microorganisms. On Earth, PAHs were known to occur in thousands of forms, but in the Martian meteorite they were dominated by only about a half dozen different compounds. The simplicity of this mix, plus the lack of lightweight PAHs (such as naphthalene), made them substantially different from the PAHs measured in non-Martian meteorites.

Zarelab had found
• In 1989, the British group led by Ian P. Wright and including Gibson’s friend Colin Pillinger had reported the detection of “nonspecific carbonaceous material” in another Martian meteorite, EETA79001. (This was the SNC in which trapped gases had first been found to match the composition of Mars’s atmosphere.) The findings represented the first tentative detection of Martian organic material, and they generated a column by Isaac Asimov (Los Angeles Times Syndicate, Aug. 28, 1989). However, many researchers dismissed the results on grounds that the material was not Martian but terrestrial contamination. Later, when the McKay team published the Zarelab results, they would be criticized for not noting the British group’s earlier work. Subsequently some of the same scientists who had dismissed the earlier findings would attack the new ones on similar grounds. See Steven J. Dick and James E. Strick,
The Living Universe
(New Brunswick, N.J.: Rutgers University Press, 2004), pp. 195–96.