Passing comet peppered Mars with shooting
stars, scientists say
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[November 08, 2014]
By Irene Klotz
CAPE CANAVERAL (Reuters) - The comet that
sailed by Mars last month spawned thousands of shooting stars per hour
and created a new layer of ionized particles high in the planet’s
atmosphere, NASA scientists said on Friday.
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At twilight, the Martian skies likely took on a yellowish hue from
sodium in vaporized comet dust, creating a glow similar to sodium
vapor lights commonly used in parking lots on Earth.
“To see (that) many shooting stars happening at once, I think it
would have been really mind-blowing,” planetary scientist Nick
Schneider, with the University of Colorado in Boulder, told
reporters on a conference call.
Scientists used a fleet of robotic spacecraft circling Mars to study
Comet Siding Spring, which passed just 87,000 miles (139,500 km) by
Mars on Oct. 19. That was less than half the distance between Earth
and the moon, and 10 times closer than any known comet that has
passed by Earth.
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The comet was a rare visitor from the Oort Cloud, a spherically
shaped reservoir beyond Neptune’s orbit containing leftovers from
the formation of the solar system some 4.6 billion years ago.
Comet Siding Spring "probably has never been in to the inner solar
system before,” said Jim Green, head of NASA’s Planetary Science
Division in Washington.
The comet also left an imprint on Mars, depositing thousands of
pounds of dust into the atmosphere, far more than computer models
had predicted.
NASA had moved its orbiting spacecraft so they would be behind Mars
and shielded from dust impacts at the peak of the storm.
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“I really believe that hiding them like that really saved them,”
Green said. “We ended up with a lot more dust than we ever
anticipated.”
Measurements taken before and after Siding Spring’s approach show
significant changes in Mars’ upper atmosphere, including the
addition of a new layer of charged particles and telltale chemical
fingerprints of magnesium, iron and other metals shed by the passing
comet.
Analysis is ongoing to determine the comet’s size, composition and
other attributes.
The comet is named for the Australian observatory that discovered it
last year.
(Reporting by Irene Klotz; Editing by Leslie Adler)
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