by Barry Lopez
The dominant winds of the Antarctic interior are katabatic—driven by gravity—not cyclonic. (Cyclonic winds are generated by changes in air pressure.) One way to think of katabatic winds is to picture them as gargantuan cataracts of air moving over the ice sheets. Because the pull of gravity is a constant, the direction of the flow of air hardly varies for a katabatic wind—it flows downhill as a river would on a slope. The force behind this river of air, however, does change, with the volume of falling compressed air, the changing contours of the ice surface, and the gusting of the wind.
Wherever the deep layers of an ice sheet are forced to flow vertically, they encounter the scouring effects of a katabatic wind as they reach the surface. These winds do two things that make Antarctica a mecca for meteoriticists. They shatter the crystals of any snowflakes that fall on the bare surface of emerging ice, scattering the debris and keeping the ice surface clean; and in a process called sublimation, the winds vaporize the ice as it emerges, turning it from a solid to a gas. There is no intermediate liquid stage. Over time, as the ice sheet continues to flow vertically and as the wind continues to erode the ice, embedded meteorites are left stranded one by one on the surface. Over millennia, the concentration of meteorites on these stranding surfaces can become very large, some concentrations running into the thousands.
Once scientists came to understand how this concentrating mechanism worked, they began systematically searching old aerial photographs of the Transantarctic Mountains for blue-ice fields, as they came to be called. Additional ground reconnaissance determined which blue-ice fields had the highest concentrations of meteorites. Available funding from the NSF, and the logistical complexities associated with putting a small scientific party in the field for five or six weeks, determined which sites might be most readily exploited. In keeping with Antarctic Treaty protocols, each meteorite found by members of a field party belongs collectively to every country that is a signatory to the Antarctic Treaty. The meteorites, including the ones we were finding, are shipped to NASA’s Johnson Space Center in Houston, Texas, where they are made available to any qualified scientist. The name of the individual who finds a particular meteorite is not entered into the collection record, out of respect for the spirit of equality and common cause that the treaty embodies.
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THREE YEARS AFTER the reconnaissance at Graves Nunataks, the six of us found ourselves at this dependably windy site, prepared finally to begin work midway through what was then the stormiest and shortest field season in the twenty-three-year history of the NSF-sponsored Antarctic Search for Meteorites (ANSMET).
Viewed on a grand scale, our camp at Graves sat on the periphery of what amounted to a back eddy in the flow of the ice sheet moving off the polar plateau. The back eddy was created by the nunataks, outliers of the main mass of the Transantarctic Mountains. Far to the east of us, the flow of ice broke into two separate streams around the La Gorce Mountains, a part of the Transantarctics. The northern stream became Robison Glacier, the southern stream Klein Glacier. Thirty miles farther north and east, these two glaciers flowed into, and became part of, Scott Glacier, which descends through the Queen Maud Mountains and becomes a part of the Ross Ice Shelf. This ice, carrying a load of meteorites that never happened to emerge at the surface, ultimately calves into the Ross Sea, an embayment of the Southern Ocean. The calved ice might be released in the form of a tabular iceberg more than a hundred square miles in extent, or set loose as a small ice floe that soon melts somewhere in the vicinity of Antarctica, dropping its meteorites to the bottom of the Southern Ocean. From there, these fragments from the asteroid belt, from Mars, and from Earth’s moon, find their way eventually into the planet’s upper mantle.
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ONCE TAKEN IN HAND and placed under a microscope, each meteorite is revelatory. The overwhelming majority of them come from the asteroid belt, between Mars and Jupiter, and are so distinctive, one from the other, that scientists have been able to create a kind of geography of the asteroid belt, a geologic map that allows them to push deeper into our still-hazy understanding of how the solar system evolved. In short, every meteorite represents an important contribution to the unraveling of the mystery of Earth’s origin. Therefore, though the six of us will find only 186 meteorites—the fewest ever by an ANSMET field party—our weather-compromised effort will still be viewed as successful.
Ross Ice Shelf Region
There are several nunataks at Graves Nunataks, all peaks of the same mountain. Each one is slowly shedding its weather-exposed face, which falls to the stranding surfaces below as rocky debris. To search efficiently for meteorites also stranded on the ice, each of us must learn to visually separate this terrestrial debris from extraterrestrial material. On our first day here, then, we climb up to the exposed ridge of one of the nunataks to examine and memorize the color and grain patterns of the rock there. Later, when we’re lined out on the stranding surfaces and walking six abreast, we’ll be able to visually sort the rocks resting on the ice, mentally discarding everything but a meteorite. A shout from one of us will bring the others to a stop. We’ll each mark the place we’re standing at that moment and then gather around the find.
We fix the location of the meteorite using a GPS device and record its general characteristics in a field notebook—the species of meteorite, its size, color, shape, and whatever else about it that seems noteworthy. One of us then picks the meteorite up with a pair of sterile tongs and deposits it in a sterile transparent collection bag, which is then sealed. Back in camp, certain meteorites might be examined once more before being packed in reinforced cases for transshipment, first back to McMurdo aboard an LC-130, then to the Astro Materials Acquisition and Curation Office at the Johnson Space Center, and eventually to the Smithsonian, in Washington, D.C.
John has been doing this for so long he’s able to make an informed guess about the pedigree of nearly every meteorite we find. And he’ll often notice that three or four meteorites we’ve just collected are all part of a single meteoroid that shattered on impact. It’s as if the images of meteorites he’s seen over all those years drift through his memory like the faces of people he remembers.
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JOHN CRAWLS IN through the snow tunnel and begins stripping off his weather gear. With both cookstoves going, the tent is relatively warm, about 40° F just above floor level and over 50° F where the tent walls meet at the tent’s apex. (We hang damp socks, boot and glove liners, handkerchiefs, and scarves up there to dry.) It’ll stay that way until we shut the stoves off when we go to sleep.
Now that John’s fixed the track assembly on the snow machine, he’s fiddling with our radio, which has been acting up. At this point, in the middle of his nineteenth season, John is the best-known scientist associated with the ANSMET project, after Bill Cassidy, the visionary who started these searches in 1976. (It was during his second field season that John and Ian Whillans found the golf-ball-size meteorite near the Allan Hills that turned out to be a lunar breccia, the first piece of the moon identified on Earth.)
I tell John about the meteorite I found on my walk around the perimeter of the camp that evening. While I cook and he rewires the antenna lead to the radio, we talk through a plan for the days remaining to us. He tells me we have had so many delays to start with, and so many tent-bound days since we arrived, that ANSMET will have to come back the following year, or maybe the year after that, to finish searching the stranding surfaces here. With just a few days left, John’s leaning toward more reconnoitering, with less time spent actually collecting. Tomorrow, he says, we should search around the southern flank of the nunataks and probe bays in the steep east face of the mountain for any concentrations of meteorites. We might collect some of the larger ones but should concentrate on flagging as many meteorites as we can and sketching them in on a map we’ll draw for each bay.
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nbsp; While I finish up the dishes, John visits with the others in their tents. He tells them that if the wind doesn’t pick up tonight and we still have sufficient contrast under these cloudy skies to read the surface of the snow for crevasses, we’ll leave again in a few hours. He wants us to climb a steep ice slope on the west flank of the nunataks and then search to the east, along the nunataks’ south flank, for any meteorite concentrations. He wants at least this one quick look at the only side of the nunataks we’ve not visited yet. Three of our group are uneasy about climbing the slope with snow machines, but John exudes a kind of understated confidence in the three of them, which they trust.
While he’s out, John chips a bucketful of ice from the glacier our tent sits on to replenish our water supply. (When we’re weathered in, we still must leave the tents to get ice to melt for water. We also always refuel our cookstoves out there, to be absolutely certain we’re not close to anything flammable in case of an accident.)
When he returns, John has Scott in tow. He asks if the two of us would mind collecting the meteorite I’ve just found while he concentrates on transferring some of the GPS coordinates he’s been writing down onto sketch maps of the bays we’ve been working in.
Whenever I’m the one tasked with taking notes while we collect a meteorite, I’m aware of the precision and finitude of the numbers I’m writing down, of how infinitesimal these particular data points are in the overall effort scientists make to understand what happened 4.5 billion years ago, during the early stages of the geological development of a planet on which the conditions to support biological life would develop, 93 million miles from a nuclear furnace that circles us each day along the horizon, the track of a halo tilted slightly to the south.
The following evening, after we return from our reconnaissance on the south side of the nunataks, John and I fall into conversation about the ultimate significance of our work. We’re at a point in the expedition where a question like this often arises, during the closing days, when what still needs to be done comes under intense scrutiny. Like most good scientists, John is not entirely convinced of the ultimate authority of the rational mind, and he recognizes the potential for peril in strict cause-and-effect reasoning. He doesn’t like the way much of science, particularly laboratory science, discounts awe and mystery, as though the capacity to respond to reality in this way was something to outgrow. I tell John that in the years I’ve been coming to Antarctica and working with different field parties, I’ve watched the scientific respect for “data sets” supplant scientific respect for firsthand field experience, and have wondered where this trend will lead. I’ve worried about the impatience with which the inevitable loose ends and inconclusiveness of fieldwork is often met, and the modern preference for theory, and the recruitment of numerical data to support one or another theory.
Back in McMurdo we’ve both witnessed changes as the hallways of the old science building, perennially crowded with camping gear, have given way to the antiseptically tidy and brightly lit hallways of the Crary Science and Engineering Center. The corridors of the new building buzz with the ceaseless clicking of keyboards, a kind of white noise accompanied by the electronic beeps that signal a task has been completed or information is now awaiting retrieval. The numerical results of a theoretical approach, of someone’s plumbing the nimbus of numbers surrounding a little-understood event, are both esoteric and arcane; and the speed with which they’re produced, and the sheer volume of them, is intimidating. The process suggests that knowledge has been obtained, but in fact there is not much more here than staggering precision and a quantity of numbers significant enough to support statistical probability. Massive data sets represent irrefutable truth for some, or insights that transcend previously established boundaries, but the data might be no more than intensely self-referential. Impressive but unconvincing.
The belief that one can reach a state of certainty about anything acts as a goad for those who regard the anomalies that inevitably turn up in their data not as a caution but as an inconvenience.
“I had a theology professor once,” I said to John, “who told us that religion was not about being certain but about living with uncertainty. It was about being comfortable with doubt, and maintaining the continuity of one’s reverence for a profound mystery.”
I wasn’t sure John heard me. He was reclined on his sleeping bag with only his lower legs visible to me past a pile of gear. Perhaps he’d fallen asleep. It’d been a long day.
“We gain deeper knowledge,” he responded. “But no guarantee that we’re any closer to wisdom.”
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A FEW HOURS after we fell asleep that night, the wind woke me, punching the tent wall behind my head, a creature moved to a state of rage. Its caterwauling, its screaming wail, the pitch of it rising and falling, the decibels of it, would all suddenly collapse nearly to silence, then mount again. The sound of it shimmered in my ear, like light striking the eye from a sheet of shaken foil. The tent shuddered on its stout poles and the tent fabric strained at its triple-sewn seams, seething and popping. The inconstant tympanic thrumming of the fabric was an intonation underlying one shrieking run after another of banshee notes, some of them single tones within the squalling wind that sustained themselves for several seconds before dropping an octave. It might be hours of this before stillness returned. Or days. Or it might all fall apart and cease in a few minutes.
The day that we climbed to the summit of one of the nunataks at Graves, to orient ourselves and to examine shattered slabs of sedimentary and metamorphic rock on the ridge, our footsteps generated the sounds of broken crockery. I turned one rock after another over in my gloved hands, to get its measure, to take it in more completely. In the absence of any other kind of life, these rocks seemed alive to me, living at a pace of unimaginable slowness, but revealing by their striations and cleavage, by their color, inclusions, and crystalline gleam, evidence of the path each had followed from primordial birth to this moment of human acquaintance. Each rock I examined, all of them ostensibly remnants of the same dark slabs, was nevertheless distinguished from the others by some rosette of color, some angularity that made it stand apart. As I sat there, reluctant to put down a single one of these “undistinguished” rocks, contemplating the history of each one in the gigantic sweep of time that was for them a “lifetime,” they suddenly seemed wilder than any form of life I’d ever known. Like the wind, they opened up the landscape.
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SINCE THERE WAS no telling when a storm might make travel back to Klein Glacier difficult, or indeed impossible, and with the cargo planes scheduled to land there on January 20, John has decided to take advantage of a period of clear weather on the eighteenth to break camp. We’re so conscious of how many days we’ve been tent-bound, feeling so aggrieved about the attenuated search for meteorites, it’s hard for us to capitulate, but John’s right. We’re done. We pack the sleds and leave for the landing zone under cloudless azure skies, sailing through great intermontane basins of calm air. A trip that had taken us more than fourteen hours, stopping and going, several weeks before, we now make in just four and a half hours. We erect a temporary camp on Klein Glacier. John gets the radio going and tells McMurdo we’re safely there. McMurdo says only one Herc will be coming for us on the twentieth. The second will come in on the twenty-first, so we’ll go out in two groups.
It takes most of the afternoon to unload the sleds and restage our gear on the pallets we left here, to prepare everything for the planes. When we’ve finished, we depart on our snow machines, headed for a valley at the foot of the La Gorce Mountains, several hundred square miles of unexplored, steeply pitched heights and deep valleys, first sketched out on a map of Antarctica in 1934, during an aerial reconnaissance.
To enter what is actually a cirque on the southwest side of one of the range’s most prominent ridges, we must descend a steep slope of glacial ice.
Moving laterally from one patch of snow to another—the snow machines have better traction here than on bare ice—keeps us from losing control on the descent; climbing out, we’ll use the same snow patches, like stepping-stones, skittering from one to another. The mouth of the cirque is about four miles wide, an amphitheater about as deep as it is wide. The floor of the valley is a felsenmeer, a sea of shattered rock that has fallen over many millennia from heights a thousand feet above us.
The dark granite rubble of the felsenmeer, warmed by the sun, radiates an impressive amount of heat. John and I each find narrow slots between boulders in which to lie supine. We’re protected from a light breeze that’s blowing and bathed in sunlight. The air temperature is about 5° F, but it feels twenty degrees warmer in these “solar ovens.” They offer us a kind of threshold, a road to another country.