Trent J. Perrotto
Headquarters, Washington
202-358-0321
trent.j.perrotto@nasa.gov
Whitney Clavin
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-4673
whitney.clavin@jpl.nasa.gov
RELEASE: 11-354
NASA'S SPITZER DETECTS COMET STORM IN NEARBY SOLAR SYSTEM
WASHINGTON -- 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 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., 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:
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