October 21, 2006
APL Meteorite Hunters Travel to Antarctica
Field Work Takes Staff Members on Search for Space Rocks
Some APL staffers go to the ends of the Earth and back in the name of science. Several members of the Space Department (Nancy Chabot, Ben Bussey, Cari Corrigan, and Andrew Dombard) have spent time in Antarctica collecting meteorites as part of the Antarctic Search for Meteorites (ANSMET) program.
The purpose of ANSMET, funded by the National Science Foundation's Office of Polar Programs and NASA, is to find and characterize meteorite samples in Antarctica and make those samples available to researchers worldwide. Since its inception in 1976, ANSMET has provided the scientific community with more than 15,000 meteorite specimens. These samples are a unique way to study outer space without actually leaving the planet, and they can offer important clues about the formation of the solar system and the compositions and histories of asteroids and other planetary bodies.
Antarctica is uncommonly fertile ground for meteorite hunting (about 85% of all meteorites recovered worldwide are found there). In some areas, the Antarctic ice sheet, nearly 2 miles (approximately 3,000 m) thick, effectively buries the continent and allows little to no accumulation of indigenous sediment. That means that any rocks found on the surface are likely extraterrestrial. Surface rocks are also easy to spot because they contrast starkly with the homogeneously icy landscape.
Antarctica's ice flow acts as a natural concentration mechanism. As the ice sheet creeps across the continent, it occasionally bumps into mountain ranges and other obstructions beneath the ice. When strong winds strike such areas, they remove large accumulations of snow and ice, exposing clusters of meteorites on the surface.
Rough Rides—Hard Work
Individual ANSMET missions last 8 weeks—6 spent looking for meteorites with a week at either end for preparation and cleanup. The journey to Antarctica begins in New Zealand, where team members assemble their gear. The flight to Antarctica is an adventure in itself. Dombard, a scientist in the Space Department's Planetary Exploration Group, says the group was "packed in like sardines for 7 hours, and it was very noisy. It's especially uncomfortable if the weather is bad." On Dombard's trip it took four tries to get down there, when Antarctic weather cancelled the flight or forced the plane to turn back to New Zealand after making it halfway.
The 8-week sojourn in Antarctica has its own hazards. That's why researchers participate in a 2-day survival school, learning how to cope with the inhospitable climate and how to execute a rescue if something goes wrong. Chabot, also a scientist in the Planetary Exploration Group, has visited Antarctica five times. She describes a typical day on the meteorite trail: "We would wake up, eat breakfast in the tent, dress warm and get prepared for the day—with plenty of sunscreen—the Sun is up 24 hours a day in the summer season" Then each member of the team would get on a snowmobile and travel to the ice field to search for meteorites.
Lunch usually consisted of beef sticks and beef jerky and lots of chocolate. The team would get back to camp before 6 p.m., fuel the snowmobiles, catalog and record the meteorites of the day, melt ice for water, cook dinner, and relax before trying to get a good night's sleep. "Being constantly out in the cold takes a lot out of you, and you need lots of sleep," Chabot adds. Average temperatures were generally 14 to –4 degrees Fahrenheit, without wind chill considerations.
The hunt involves driving in systematic grids to cover the ice area, stopping whenever someone finds a meteorite. "Some days were slow," Chabot says, "and we'd find less than 10 meteorites. But other days, we collected more than 100 in one day."
Even with the inherent hazards and obstacles, the scientists say the trip is worth the risks. "It's such a unique opportunity," says Chabot. "You deal with being cold, being dirty, and other hardships…but when you go outside and look around, it's so beautiful, it just puts everything else into perspective."
Contributing scientists/photographers: N. Chabot, B. Cohen, G. Osinski, J. Pierce, L. Welzenbach