[meteorite-list] What Would Happen If Asteroid Hits Mars

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Fri, 4 Jan 2008 15:03:47 -0800 (PST)
Message-ID: <200801042303.PAA14934_at_zagami.jpl.nasa.gov>

http://www.foxnews.com/story/0,2933,320410,00.html

What Would Happen If Asteroid Hits Mars
By Leonard David
space.com
January 4, 2008

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 blow 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 circling 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.
Received on Fri 04 Jan 2008 06:03:47 PM PST