Contacts: Barbara Cohen, (505) 277-3345
Steve Carr, (505) 277-1821
May 10, 2004
UNM RESEARCH ASSISTANT PROFESSOR SPENDS TIME IN ANTARCTICA SEARCHING FOR METEORITES
There are probably much better places to spend 40 days than searching for meteorites in the frozen, wind blown tundra of Antarctica. But for Research Assistant Professor Barbara Cohen in the Department of Earth and Planetary Sciences it was the opportunity of a lifetime.
As part of the Antarctic Search for Meteorites (ANSMET) program, funded by the National Science Foundation (NSF) and NASA, Cohen was one of 10 researchers selected to participate in the latest expedition this winter (summer in Antarctica).
Antarctica is a hot bed of meteorites. More than 25,000 have been collected under the ANSMET program, which began in 1976 when the NSF provided support for a meteorite expedition led by researcher Bill Cassidy. Cohen’s group found more than 1,300 meteorites on their trip.
Meteorites fall randomly over the Earth’s surface throughout time. The best place to find meteorites is in dry environments like the Antarctic. Water causes meteorites to weather. Snow accumulates, along with the meteorites, in the accretion zone. Then, due to its own weight, it becomes compacted and flows downward, turning snow into a glacier. At some point, the glacier flow is interrupted due to an obstruction, like a mountain, Cohen says.
Cold atmospheric air sinks over the South Pole. The cold air flows to a low place causing winds up to 80 knots. The dry, cold winds erode the ice away and leave concentrations of meteorites at the base of the mountain waiting to be picked up. Meteorite hunters search for areas of blue ice, which are seemingly endless expanses of nothing but clean ice from deep within the Antarctic ice sheets. It’s blue
for the same reason the sky is blue. Water scatters blue light preferentially resulting in an astonishingly
deep color. When hunters find areas like this, they’re pretty sure any rock found had to have fallen there from the sky Cohen says.
Another good place to find meteorites is in sandy deserts such as the Saharan Africa, where sand is always shifting. Meteorites stay where the sand has blown away causing a concentration effect.
Once found, the meteorites, which are generally less than one centimeter on a side, are kept frozen and put on a boat to California, then trucked to NASA’s Johnson Space Center in Houston where they are opened up under nitrogen. The meteorites are then unpacked and stored in nitrogen because it displaces water and oxygen in the atmosphere.
The meteorites then go to the Smithsonian Institute in Washington, D.C. where a team of scientists classify the meteorites and send them back to Johnson Space Center for curation and dissemination to the research community.
Cohen’s research team hopes that among the 1,300 meteorites they found, some might turn out to be lunar or Martian meteorites, although they won’t know the outcome until later this summer.
Finding the meteorites is one thing, surviving the conditions in the Antarctic, where there is daylight 24 hours a day during the summer, is quite another.
Cohen’s team was at a self-contained remote field camp, living in two-person tents. They searched for meteorites at the La Paz Ice Field, which was named after Lincoln La Paz who actually founded the meteorite collection and Institute of Meteoritics at UNM. Cohen said that it was very bright and that team members had to wear special goggles with UV protection. The wind limited their ability to stay out very long to search for meteorites.
Usually the temperature was -15 Celsius with winds of 20 knots for a wind chill of approximately -27 Celsius. On good days, they were able to stay out for about eight hours looking for meteorites.
Afterward, they would return to camp and spend time doing camp chores like fueling snowmobiles and chipping ice for water. They had about an hour or two of leisure time in the tents each night, which was spent socializing, reading and talking on the satellite phone to loved ones.
About one in five days the weather was so bad they couldn’t work. Cohen says she read “War and Peace” in its entirety while she was there.
In addition to her recent meteorite expedition, Cohen is researching the impact and geochemcial history of the moon and asteroids by looking at meteorites from those bodies. She’s also helping out on the renovation of the UNM Meteorite Museum.
# # #