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Donald Savage
Headquarters, Washington                     Feb. 27, 2003
(Phone: 202/358-1547)

Catherine E. Watson
Johnson Space Center, Houston
(Phone: 281/483-5111)

RELEASE: 03-084

NASA FINDS REMNANTS OF ANCIENT STARS IN EARTH'S UPPER ATMOSPHERE

    NASA researchers believe they have found bits of ancient stars in 
small particles gathered in the Earth's upper atmosphere. The 
researchers revealed their findings in a paper released today.

For more than two decades, NASA has collected interplanetary dust 
particles (IDPs) in the Earth's stratosphere using a modified U-2 
aircraft, the ER-2. These tiny particles include the only samples of 
comets that can be studied in the laboratory.

"The stardust grains we discovered are typical of the kinds of dust 
that were available at the beginning of our solar system, these were 
the building blocks of the sun and planets," said Dr. Lindsay Keller, 
an author of the paper and a researcher in the Office of 
Astromaterials Research and Exploration Science at NASA's Johnson 
Space Center, Houston. "Comet samples are the logical place to look 
for preserved stardust. They formed in a region of the solar system 
where they escaped the extensive processing that affected other solar 
system materials," he said.

Before the sun formed, our solar system was a swirling cloud of dust 
and gas, the remnants of dead stars from other parts of the galaxy. 
Some of this dust survived the formation of the solar system unchanged 
to end up in comets. These comets contain the ingredients of the early 
solar system, the ingredients for which came from the remnants of 
early stars in the universe.

"The fact that these IDPs are rich in stardust and molecular cloud 
material suggests that they have remained essentially unchanged from 
the time the solar system formed, 4.5 billion years ago," said Dr. 
Scott Messenger, lead author of the paper and an astrophysicist at 
Washington University in St. Louis.

The discovery was made possible by using a new kind of ion microprobe 
at Washington University, which measures isotopic ratios on scales 
much smaller than previously possible. This is essential for 
identifying stardust grains, because, "they have isotopic ratios very 
different from anything in the solar system," Messenger said. Most 
collected IDPs range in size from 5 to 50 millionths of a meter, and 
often contain crystalline grains clumped together in sizes of 100 to 
500 billionths of a meter.

The paper is on the Internet at:
http://www.sciencemag.org/sciencexpress/recent.shtml

For more information about NASA on the Internet, visit: www.nasa.gov

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