This story was updated at 11:04 p.m. EST.
The chances
of an asteroid smacking into Mars this month are slipping away as astronomers continue
to refine its course toward the red planet.
The space
rock, an asteroid
called 2007 WD5, is now expected to miss Mars by about 18,641 miles (30,000
km), according a Tuesday report by NASA's Near Earth-Object (NEO) program office.
Scientists
now estimate the space rock's odds of walloping Mars on Jan. 30 at 2.5 percent,
about a 1-in-40 chance, after a series of observations taken by astronomers
using Spain's 11.5-foot (3.5-meter) Calar Alto Observatory. The new analysis
lowered the asteroid's odds of a martian impact from a 3.6 percent chance released
last week.
"If
the estimated miss distance remains stable in future updates, the impact
probability will continue to fall as continuing observations further constrain
the uncertainties," said the report, which was compiled by researchers at
NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif.
Astronomers
at the University of Arizona first
glimpsed Asteroid 2007 WD5 last month while performing the Catalina Sky
Survey. At the time, the space rock was hurtling through space at about 8 miles
per second, which is about 28,800 miles per hour (46,349 kph) and
15 times faster than a rifle bullet, researchers said.
With an
estimated diameter of about 164 feet (50 meters), the asteroid is similar in
size to the object that slammed into northern Arizona about 50,000 years ago to
create Meteor
Crater, NASA scientists have said. Earlier analysis of the space rock's
trajectory suggested that, if it did impact Mars, it could slam into the
planet's surface at about 30,000 miles per hour (48,280 kph), release about 3
megatons of energy and leave a crater about a half-mile (0.8-km) wide, they
added.
Such an
impact could be observed by the multiple spacecraft currently orbiting Mars,
such as NASA's Mars Reconnaissance Orbiter, and provide a wealth of information
on the formation of craters and the red planet's interior, researchers have
said.
"We
estimate such impacts occur on Mars every thousand years or so," said JPL researcher
Steve Chesley, who released the refined asteroid course with
colleagues Paul Chodas and Don Yeomans, in a NASA announcement last week.
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