03.03.2006
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Dr. Peter Tsou, Deputy Principal Investigator at JPL, handles the sample container. |
Samples from comet Wild 2 have surprised scientists, indicating the
formation of at least some comets may have included materials ejected by
the early sun to the far reaches of the solar system.
Scientists have found minerals formed near the sun or other stars in the
samples returned to Earth by NASA's Stardust spacecraft in January. The
findings suggest materials from the center of the solar system could
have traveled to the outer reaches where comets formed. This may alter
the way scientists view the formation and composition of comets.
"The interesting thing is we are finding these high-temperature minerals
in materials from the coldest place in the solar system," said Donald
Brownlee, Stardust principal investigator from the University of
Washington, Seattle.
Scientists have long thought of comets as cold, billowing clouds of ice,dust and gases formed on the edges of the solar system. But comets may not be so simple or similar. They may prove to be diverse bodies with complex histories. Comet Wild 2 seems to have had a more complex history
than thought.
"We have found very high-temperature minerals, which supports a
particular model where strong bipolar jets coming out of the early sun
propelled material formed near to the sun outward to the outer reaches
of the solar system," said Michael Zolensky, Stardust curator and
co-investigator at NASA's Johnson Space Center, Houston. "It seems that
comets are not composed entirely of volatile rich materials but rather
are a mixture of materials formed at all temperature ranges, at places
very near the early sun and at places very remote from it."
One mineral found in the material brought back by Stardust is olivine, a
primary component of the green sand found on some Hawaiian beaches. It
is among the most common minerals in the universe, but scientists were
surprised to find it in cometary dust.
Olivine is a compound of iron, magnesium and other elements. The
Stardust sample is primarily magnesium. Along with olivine, the dust
from Wild 2 contains high-temperature minerals rich in calcium, aluminum
and titanium.
Stardust science team members presented their first findings this week
at the annual Lunar and Planetary Science Conference in League City, Texas.
Click here for the full press release and the images presented at the briefing.
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