This story was updated at 7:01 p.m. EST.
The
possibility of an asteroid walloping the planet Mars this month is whetting the
appetites of Earth-bound scientists, even as they further refine the space
rock's trajectory.
The space
rock in question — Asteroid
2007 WD5 — is similar in size to the object that carved Meteor
Crater into northern Arizona some 50,000 years ago and is approaching Mars
at about 30,000 miles per hour (48,280 kph).
Whether the
asteroid will actually hit Mars or not is still uncertain.
Such an
impact, researchers said, would prove an awesome opportunity for planetary science
since NASA's Mars Reconnaissance Orbiter (MRO) and a flotilla of other
spacecraft are already in position to follow up any impact from orbit.
"An impact
that we could witness/follow-up with MRO would be truly spectacular, and could
tell us much about the hidden subsurface that could help direct a search for
life or life-related molecules," said John Rummel, NASA's senior scientist for
astrobiology at the agency's Washington, D.C., headquarters.
Observations
of the asteroid between Dec. 29 and Jan. 2 allowed astronomers to slightly
lower the space rock's odds of striking Mars to about 3.6 percent (down from
3.9), giving the object a 1 in 28 chance of hitting the planet, according to Tuesday
report from NASA's Near Earth-Object program office at the Jet Propulsion
Laboratory in Pasadena, Calif.
More
observations may further reduce the asteroid's impact chances to nil, NEO
officials said. The space rock's refined course stems from observations by
astronomers at New Mexico Tech's Magdalena Ridge Observatory.
But if WD5
does smack into Mars, some astronomers have a fair idea of what havoc it may
spawn. The likely strike zone would be near the equator, but to the north of
the current position of NASA's Opportunity rover at Victoria Crater, NASA officials
have said.
Mark
Boslough, a collision dynamics expert at New Mexico's Sandia National
Laboratory, said the atmosphere at Mars' surface is similar to that of Earth at
an altitude of 12 miles (20 km). Some space rocks that target Earth explode
under the pressure created as they stream into our atmosphere. But they tend
not to explode until much below the 12-mile mark.
"So
this won't be an airburst," Boslough said. "It will either hit the
ground intact and make a single crater, or break up and generate a cluster of
craters."
The
collision, were it to occur, could also create a visible dust plume as ejecta
is lofted high into the martian atmosphere, he said.
The
resulting crater could reach more than a half-mile (0.8-km) in diameter, or
about the size of the Opportunity rover's Victoria home, NASA added.
Boslough's
break-up scenario is reminiscent of Comet
P/Shoemaker-Levy 9, which broke into more than 20 fragments as it neared
Jupiter in 1994, then repeatedly pummeled the gas giant over the course of six days.
The resulting impact scars were visible to telescopes on Earth, in orbit and
NASA's Galileo probe, which was en route to Jupiter at the time of the collision.
Like
Galileo at Jupiter, NASA's MRO probe and its High-Resolution Imaging Experiment
(HiRISE) camera would be in prime position for a martian collision. With its
ability to resolve objects three feet (one meter) across, HiRISE as been billed
as the most powerful camera ever sent to study Mars.
"If the
asteroid hits Mars, we'll get a great look at the crater within a few days of
impact," said HiRISE principal investigator Alfred McEwen of the University of
Arizona's Lunar and Planetary Laboratory in Tucson.
SPACE.com Staff Writer Tariq Malik contributed to this
report from New York City.
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