[meteorite-list] NASA's Spitzer Detects Comet Storm in Nearby Solar System

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed, 19 Oct 2011 10:22:55 -0700 (PDT)
Message-ID: <201110191722.p9JHMtJ6003519_at_zagami.jpl.nasa.gov>


NASA's Spitzer Detects Comet Storm in Nearby Solar System
Jet Propulsion Laboratory
October 19, 2011

PASADENA, Calif. -- NASA's Spitzer Space Telescope has detected signs of
icy bodies raining down in an alien solar system. The downpour resembles
our own solar system several billion years ago during a period known as
the "Late Heavy Bombardment," which may have brought water and other
life-forming ingredients to Earth.

During this epoch, comets and other frosty objects that were flung from
the outer solar system pummeled the inner planets. The barrage scarred
our moon and produced large amounts of dust.

Now Spitzer has spotted a band of dust around a nearby bright star in
the northern sky called Eta Corvi that strongly matches the contents of
an obliterated giant comet. This dust is located close enough to Eta
Corvi that Earth-like worlds could exist, suggesting a collision took
place between a planet and one or more comets. The Eta Corvi system is
approximately one billion years old, which researchers think is about
the right age for such a hailstorm.

"We believe we have direct evidence for an ongoing Late Heavy
Bombardment in the nearby star system Eta Corvi, occurring about the
same time as in our solar system," said Carey Lisse, senior research
scientist at the Johns Hopkins University Applied Physics Laboratory in
Laurel, Md., and lead author of a paper detailing the findings. The
findings will be published in the Astrophysical Journal. Lisse presented
the results at the Signposts of Planets meeting at NASA's Goddard Space
Flight Center in Greenbelt, Md., today, Oct. 19.

Astronomers used Spitzer's infrared detectors to analyze the light
coming from the dust around Eta Corvi. Certain chemical fingerprints
were observed, including water ice, organics and rock, which indicate a
giant comet source.

The light signature emitted by the dust around Eta Corvi also resembles
the Almahata Sitta meteorite, which fell to Earth in fragments across
Sudan in 2008. The similarities between the meteorite and the object
obliterated in Eta Corvi imply a common birthplace in their respective
solar systems.

A second, more massive ring of colder dust located at the far edge of
the Eta Corvi system seems like the proper environment for a reservoir
of cometary bodies. This bright ring, discovered in 2005, looms at about
150 times the distance from Eta Corvi as the Earth is from the sun. Our
solar system has a similar region, known as the Kuiper Belt, where icy
and rocky leftovers from planet formation linger. The new Spitzer data
suggest that the Almahata Sitta meteorite may have originated in our own
Kuiper Belt.

The Kuiper Belt was home to a vastly greater number of these frozen
bodies, collectively dubbed Kuiper Belt objects. About 4 billion years
ago, some 600 million years after our solar system formed, scientists
think the Kuiper Belt was disturbed by a migration of the gas-giant
planets Jupiter and Saturn. This jarring shift in the solar system's
gravitational balance scattered the icy bodies in the Kuiper Belt,
flinging the vast majority into interstellar space and producing cold
dust in the belt. Some Kuiper Belt objects, however, were set on paths
that crossed the orbits of the inner planets.

The resulting bombardment of comets lasted until 3.8 billion years ago.
After comets impacted the side of the moon that faces Earth, magma
seeped out of the lunar crust, eventually cooling into dark "seas," or
maria. When viewed against the lighter surrounding areas of the lunar
surface, those seas form the distinctive "Man in the Moon" visage.
Comets also struck Earth or incinerated in the atmosphere, and are
thought to have deposited water and carbon on our planet. This period of
impacts might have helped life form by delivering its crucial ingredients.

"We think the Eta Corvi system should be studied in detail to learn more
about the rain of impacting comets and other objects that may have
started life on our own planet," Lisse said.

NASA's Jet Propulsion Laboratory in Pasadena, Calif., manages the
Spitzer mission for the agency's Science Mission Directorate in
Washington. Science operations are conducted at the Spitzer Science
Center at the California Institute of Technology in Pasadena. Caltech
manages JPL for NASA.

For more information about Spitzer, visit http://spitzer.caltech.edu/
and http://www.nasa.gov/spitzer .

Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.
whitney.clavin at jpl.nasa.gov

Trent J. Perrotto 202-358-0321
trent.j.perrotto at nasa.gov

2011- 322
Received on Wed 19 Oct 2011 01:22:55 PM PDT

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