The Rock From Mars by Kathy Sawyer

their shared preoccupation was with vast sweeps of time and space.
    Mittlefehldt believed firmly that humans should explore space, not only to enrich human understanding of nature but as a matter of sheer survival, in case the species should need a second world to live on. (Remember the dinosaurs!) He had been at work for several years on what he hoped would be a valuable contribution to the emerging picture of what was “out there” around Earth, and how it had gotten there. It was a major project to decipher the hidden record carried inside certain asteroids, odd-shaped, beat-up rocks that swarmed along an orbital track concentrated between Mars and Jupiter.
    In 1988, in pursuit of that goal, Mittlefehldt had applied to the meteorite curators down the hall for a sample of a resoundingly ordinary family of meteorites that had most likely been knocked off the asteroid 4 Vesta in a series of collisions. Vesta’s diameter of more than three hundred miles (almost five hundred kilometers) made it one of the largest known asteroids and a rich source of the space debris that rained steadily down on Earth.
    The rocks that were widely presumed to be spawn of Vesta had been subjected to such intense heat early in their existence that they had started to melt. Mittlefehldt hoped to learn what had produced this prodigious heat in the embryonic solar system. Happily, the Antarctic had coughed up a number of new specimens in this family, and Mittlefehldt intended to study as many as he could get his hands on. His goal was to produce the first systematic study of its kind.
    One of the supposedly plain-vanilla meteorite samples that Robbie Score’s lab sent Mittlefehldt was actually from the odd rock that Score had picked up in 1984. The world knows now that it did
not
come from Vesta. But to find that out, Mittlefehldt was building on a whole history of little advances by other people who were intensely fascinated by rocks.
    On Earth, rock is the cool skin that insulates life on the surface from the inferno deep inside the planet; it is the foundation upon which civilizations were built, the universal benchmark of stability. Rock distinguishes the inner planets. Except for the little oddball Pluto, the outer planets are big gas balls with no defined surface.
    In the minerals that make up rock—natural crystalline assemblies of chemical elements—geologists can read the chronicle of Earth’s history. And in the years leading up to Mittlefehldt’s epiphany that summer day, scientists had begun to see in the rocks that fell from space, as one put it, useful “keys that can unlock the vaults of cosmic memory.”
    If Mittlefehldt’s timing had been a little off, his efforts might not have triggered such a remarkable train of events. But his unmasking of the rock happened to fit nicely with changes in the portrait of nature that had only recently begun to surface. So, thanks to his aggravated—but unhurried—curiosity, the rock’s days of obscurity were numbered.
    Once launched, however, the investigation into the rock’s hidden past would be as unguided as the rock’s own journey had been. The quest would turn into a kind of sporadic human relay race with no starting gun, no master, no one who knew where the finish line was or what it would look like. You might say it took on a life of its own.
    But first, Mittlefehldt had to figure out the salient fact: somebody had misidentified this sample.
    After Robbie Score’s hunting team shipped the rock home from Antarctica, it arrived in Houston (along with the other frozen samples in the 1984–85 season’s haul) in a big shipping container. Each specimen was sealed in its own sanitized bag and wound like a mummy with tape. The specimen then joined the growing ranks of space rocks on the second floor of the Building 31 complex.
    The meteorite suite featured a Class 10,000 clean room designed to minimize contamination. It had a special air-filtration system, and the rules required that