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:
