Antarctic Meteorite ProgramThe Program -- The collection and curation of Antarctic meteorites is a cooperative effort among NASA, the National Science Foundation and the Smithsonian Institution. The meteorites are collected by National Science Foundation science teams camping on the ice during annual expeditions, all three agencies sponsor research on the specimens.
History and Collection -- Japanese scientists first discovered concentrations of meteorites in the Antarctic in 1969. The meteorites, most of which have fallen to Earth during the past million years, have been preserved in ice and concentrated in areas characterized by stagnant, snow-free "blue ice." The meteorites are found on the surface, where they are detected as pieces as small as 1 centimeter in diameter. The mechanism that concentrates the meteorites in certain areas is not completely understood. A leading theory is that they fell on snowfields which flowed toward the edge of Antarctica, and that they became exposed where the iceflow is impeded by obstacles and the ice is ablated by wind and abrasion. Ablation rates of the ice where meteorites have been concentrated have been measured to be as high as 10 centimeters per year. The frozen meteorites have not been exposed to water, and thus show less weathering than meteorites found in temperate climates. Because of the absence of industrial pollutants, they remain relatively uncontaminated. Extra efforts are made to document each sample, to provide clean containers, and to maintain the frozen samples in a cold environment until the adhering snow and ice can be removed in the laboratory by sublimation.
Preservation -- Since 1969, almost 10,000 pieces of meteorites have been collected in Antarctica, possibly doubling the total number of meteorites available for scientific study. Since 1977, the still-frozen meteorites have been returned to NASA's Johnson Space Center, Houston, for curation and distribution. Some of the specimens are forwarded to the Smithsonian Institution, but JSC scientists curate more than 10,000 meteorites for more than 250 scientists worldwide. Several hundred new meteorites arrive each year. In JSC's Meteorite Processing Laboratory, the samples are procesed in controlled atmosphere cabinets formerly used to process lunar samples. The water- and oxygen-free nitrogen gas in the cabinets keeps the meteorites from oxidation (rusting) and from contamination by environmental pollutants such as organic compounds, heavy metals, and salts. The meteorite samples are chipped, sawed, weighed, and photographed in the nitrogen cabinets without exposure to the air.
Scientific studies -- Among the recovered meteorites are pieces blasted off the Moon and Mars by impacts. Because meteorites in space absorb and record cosmic radiation, the time elapsed since the meteorite impacted the Earth can be determined from laboratory studies. Meteorites are important scientifically because they were formed during the earliest history of the solar system -- some may even contain pre-solar system remains -- and can provide information about the physical and chemical makeup of the solar system.
|Curator: Annie Platoff
Responsible NASA Official: Kelly Humphries
Last Updated: 6 August 1996