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Hunting Antarctic Meteorites

University of Arizona News Release

2005 November 10

Not many people celebrate their year-end holidays on the east Antarctic ice sheet. But nearly every year for more than a decade, University of Arizona Lunar and Planetary Laboratory (LPL) professors, graduate students or alumni have.

They have been part of the Antarctic Search for Meteorites (ANSMET) program, intent on collecting pieces of asteroids, the moon and Mars which have landed as meteorites on the whitest place on Earth.

"ANSMET is such an amazing program," UA postdoctoral researcher Jani Radebaugh says. "It's like getting free samples from outer space, free except for the cost of traveling to Antarctica to collect them."

Radebaugh is among 15 scientists and mountaineers selected for the 2005-2006 NSMET program. So is Gordon Osinski, a recent LPL postdoctoral researcher now with the Canadian Space Agency. The 20-year-old ANSMET program is funded by the National Science Foundation Office of Polar Programs and by NASA's Solar System Exploration Division. Planetary scientist Ralph Harvey of Case Western Reserve University heads the collecting expeditions.

"The program is a wonderful thing, because now there's a push to go back to the moon and Mars and return samples to try to understand these bodies," Radebaugh said. "We can learn a lot more about these bodies as we increase the collection of the samples that land on Earth. I think these expeditions are a really important service to planetary science."

Radebaugh, who earned her UA doctorate last May, will join the Brigham Young University geology faculty this fall. "I think this experience would be fun for students to hear about," she added.

Postodoctoral researcher Julia Goreva was on the successful 2004-2005 meteorite collecting expedition. She and 11 others collected 1,230 meteorites. Among these were more than 300 pounds of "pallasite" meteorites -- rare rocks originally from the core-mantle boundary of a small destroyed planet or a large asteroid. One pallasite, the largest yet found, weighed 70 pounds.

"For the past 10 years I've been studying meteorites -- destroying them, dissolving them, melting, burning, getting every bit of information they can give me about the processes that took place at times when the Earth was just an embryo," Goreva said. "ANSMET is a program that builds a collection available to any scientist around the globe, so it was very important for me to become one of the people who can personally contribute to the pool of rocks that continue to puzzle me in the lab."

Radebaugh leaves for New Zealand on Nov. 17. Expedition members get completely outfitted at Christchurch, N.Z., then board an LC 130 cargo airplane for an 8-hour flight to McMurdo Station, Antarctica. Bad weather can mean turning around mid-flight and returning to Christchurch. It took one expedition four tries to reach McMurdo.

After survival and other training at McMurdo, Radebaugh, Osinski and their colleagues will head for the Antarctic plateau inland of the Miller Range in the Transantarctic Mountains and set up base camp. They'll live in 2-person tents for five weeks during the South Polar summer, when temperatures hover around minus 30 degrees Fahrenheit.

Goreva said, "I never thought that two girls could eat a pound of butter per week and a pound of bacon for breakfast. That does keep you warm!"

Antarctica is by far the best place on Earth to search for meteorites, mainly for two reasons, Ralph Harvey explains on the ANSMET Website, One is that although meteorites fall randomly all over the globe, they are more easily found against Antarctica's plain, bright ice than on other Earth surfaces. The other has to do with the fact that as snow accumulates on the continental ice sheet, the weight pushes the ice sheet toward the edges of the continent.

"As this big, very thick ice sheet slowly spreads out, it moves like a conveyor belt and delivers meteorites to the bases of mountains," Radebaugh said.

Over tens of thousands of years, phenomenal concentrations of meteorites can develop, as high as one meteorite per square meter in some places, Harvey says on the ANSMET Website. The ANSMET program archives all its meteorites at NASA's Johnson Space Center in Houston.

That many LPL researchers have been on the Antarctica meteorite-collecting teams shows "just how involved the LPL is in the planetary science community," Radebaugh said. "The lab has a big group of people doing different kinds of research. The UA is a strong institution in planetary science. And, I also think many of us became involved because we have so many friends who have gone, and they know how exciting it is, how much fun."

"Antarctica is the most amazing place I've seen in my life," Goreva said. "At times it was breathtakingly beautiful, at times harsh and angry, but always pure, and it made me feel, well, very small. It was an overwhelming feeling to realize that you are the first person to be in that particular place in the world. (Goreva was on the 4-person reconnaissance team, the advance group for the 8-person collecting team, last season.) Except for the four of us, there was not a single living being hundreds of miles around."

Goreva added, "One of the first questions people ask is if spending two months on the ice was worth it. The short answer is -- every second of it. Would I do it again? In a heartbeat."

Lunar and Planetary Lab scientists who have been on ANSMET expeditions include:

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