Physicists study cosmic rays in Antarctica

Friday, December 26, 2003

ST. LOUIS -- A group of physicists from Washington University in St. Louis looking to catch a few rays are taking a trip south.

Way south.

All the way to Antarctica.

During a trip that may last up to a month, the scientists are monitoring a 450-foot-tall balloon as it circles 20 miles above the icy continent. The balloon, launched last week, is collecting cosmic rays -- charged atoms blasted here by exploding stars.

Washington University physicist Bob Binns called the experiment a kind of "sample recovery" from distant worlds.

"We'll never go to these stars," Binns said. "These cosmic rays deliver the material right to our doors."

The icy continent is the ideal location for the scientists to collect the cosmic rays. In December, the sun shines all day on Antarctica. Plus, the research balloon doesn't have to cross any borders during its flight.

The team plans to stay at McMurdo Station, the largest outpost on the continent, for the duration of the balloon's journey. Scientists hope the trip will last as long as a month, which would give the balloon time for two laps around the continent.

Physicists hope the Trans-Iron Galactic Element Recorder, or TIGER, experiment will help clear up a debate over the origin of the cosmic rays.

Some believe the rays came from hot stars, emitted in what is called stellar wind. Others say the particles were part of cool dust or gases far from stars before they were sent on their galactic journey.

The TIGER device detects the relative amounts of charged zinc, rubidium and germanium. Scientists have learned that these rare elements are more likely to be found in the stellar wind. Physicists figure high levels of the elements would suggest the cosmic rays actually come from hot suns.

"One has to infer the kind of place they came from because we can't point back to the star they came from," said Washington University physicist Martin Israel, a collaborator on the project.

TIGER, which is funded by NASA, was flown once before, setting a balloon endurance record with a 32-day flight over Antarctica in 2001. That flight, like this one, began at Williams Field, a desolate outpost 10 miles outside of McMurdo.

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