The Rock From Mars by Kathy Sawyer Page A

anyone entering take off all metal jewelry, don a surgical-type cap, gown, and shoe covers, and pass through an air shower.
    The complex had a culinary air about it, with its bright lights, pristine tables, cabinets like industrial refrigerators, and ovens. Some of the samples in their plastic wrap rested in metal containers that resembled lasagna pans. But then there were the arms. Disembodied black-rubber arms, with hands, waved and swayed organically in the moving air currents as if beckoning—or cautioning. The lab technicians would put their own arms inside, reversing the gloves to the inside of the chambers, in order to work on the rocks without breaching the sterile environment.
    Here, the curators weighed the rock from Allan Hills and recorded a deliberately superficial description. A technician equipped with a small silver hammer and a rock saw, operating inside the rubber arms, attacked the rock from the angular, “hackly” end (as opposed to the smooth, blocky end) and split off one-half gram for dispatch to the Smithsonian Institution in Washington, where it was to be analyzed and classified in more detail. The mother rock stayed in Houston, in the archives, usually put away in a nitrogen cabinet and sealed in a nylon bag.
    In late spring of 1985, the chip from the Allan Hills rock—resting in a tiny box like an engagement ring—arrived at the Smithsonian’s National Museum of Natural History. Upstairs from the exhibitions and down some long pastel-drab corridors that resembled those of Building 31 in Houston was an office and laboratory complex off-limits to tourists.
    There, the task of classifying the Allan Hills rock fell to a young meteorite curator named Glenn MacPherson, a relative newcomer to the job whose boss was away on a sabbatical. With Robbie Score’s rock, which was not designated as a high priority, he did the same thing he would do with some six hundred such samples flowing through his lab that season. In due course, a techician sliced, ground, and polished the sample into sections so thin they were transparent (thinner than a piece of paper). These sections could be used over and over by different researchers, like a library book.
    After the usual prep work, MacPherson examined the shard through an electron microprobe that showed its chemical composition. After about half an hour, he decided the rock was a piece of an ordinary asteroid. His finding appeared in the August 1985
Antarctic Meteorite Newsletter,
a description of the season’s haul circulated to those who might be interested in requesting samples for research.
    The newsletter first presented Roberta Score’s eyeball assessment: “Eighty percent of this rectangular-shaped [meteorite] is covered with dull black fusion crust. . . . Areas not covered by fusion crust have a greenish-gray color and a blocky texture. Cleavage planes are obvious on some large crystal faces and the stone has a shocked appearance.” She had noted small areas of oxidation and abundant small black grains scattered throughout, adding, “Small fractures are numerous.” She had judged it to be an achondrite, a rare kind of stony meteorite.
    Following that paragraph was MacPherson’s microscopic analysis, classifying the rock as a “diogenite” (i.e., a common igneous rock from an asteroid, most likely 4 Vesta). He got the basics right: “The meteorite consists of orthopyroxene . . . that forms a polygonal-granular mosaic. . . . Veins of intensely granulated pyroxene cross cut the section. . . . Other phases include minor chromite and irregular patches of a featureless and isotropic maskelynite. The section . . . does contain patches of brown, Fe-rich [iron-rich] carbonate.” He attributed this odd rusty character—odd for this type of meteorite—to weathering that had occurred on Earth.
    The rock had fooled him, true. But this was in part because MacPherson felt honor-bound under the ground rules laid down by meteorite investigators
not
to learn