Collecting Meteorites in Antarctica

Searching Meteorites in Antarctica
January 26th, 2006
Google Tech Talk
Length: 42:52



Every year since the late 70's the US National Science Foundation has supported a team of space scientists (ANSMET) to search for meteorites in Antarctica.


What is ANSMET?


Since 1976, the Antarctic Search for Meteorites program (ANSMET), funded by the Office of Polar Programs of the National Science Foundation, has recovered more than 10,000 specimens from meteorite stranding surfaces along the Transantarctic Mountains. The ANSMET specimens are currently the only reliable, continuous source of new, non-microscopic extraterrestrial material, and will continue to be until future planetary sample-return missions are successful.


The samples already recovered provide essential "ground-truth" concerning the materials that make up the asteroids, planets and other bodies of our solar system, and their continued retrieval is the cheapest and only guaranteed way to recover new things from worlds beyond the Earth.


The study of ANSMET meteorites has greatly extended our knowledge of the materials and conditions in the primeval nebula from which our solar system was born, revealed the complex and exotic geologic nature of asteroids, and proved, against the conventional wisdom, that some specimens represent planetary materials, delivered to us from the Moon and Mars, free of charge.


Why Antarctica?


Antarctica is the world's premier meteorite hunting-ground for two reasons. Although meteorites fall in a random fashion all over the globe, the likelihood of finding a meteorite is enhanced if the background material is plain and the accumulation rate of indigenous sediment is low.


Consequently the East Antarctic icesheet, a desert of ice, provides an ideal background for meteorite recovery- go to the right place, and any rock you find must have fallen from the sky. This allows the recovery of meteorites without bias toward types that look most different from earthrocks (a problem on the inhabited continents) and without bias toward larger sizes. But another factor may be equally important. As the East Antarctic icesheet flows toward the margins of the continent, it's progress is occassionally blocked by mountains or obstructions below the surface of the ice. In these areas, old deep ice is pushed to the surface and can become stagnant, with very little outflow and consistent, slow inflow. When such places are exposed to strong katabatic winds, massive deflation results, removing large volumes of ice and preventing accumulation of snow while leaving a lag deposit of meteorites on the surface. These areas exhibit a variable balance between infall, iceflow and deflation, all of which are intimately tied to environmental change during recent Antarctic history. Over significant stretches of time (tens of thousands of years) phenomenal concentrations of meteorites can develop, as high as 1 per m2 in some locations.


Terrestrial exposure ages of meteorites suggest that some stranding surfaces may have been active for hundreds of thousands, or even millions of years. Antarctica is by far the best place on Earth to search for meteorites, and the ANSMET program has proven to be the most reliable and economic way to recover these specimens.