Mars Could Be in for an Asteroid Hit by Associated Press, Los Angeles, December 22, 2007
Mars could be in for an asteroid hit. A newly discovered hunk of space rock has a 1 in 75 chance of slamming into the Red Planet on Jan. 30, scientists said Thursday.
"These odds are extremely unusual. We frequently work with really long odds when we track ... threatening asteroids," said Steve Chesley, an astronomer with the Near Earth Object Program at NASA's Jet Propulsion Laboratory.
The asteroid, known as 2007 WD5, was discovered in late November and is similar in size to an object that hit remote central Siberia in 1908, unleashing energy equivalent to a 15-megaton nuclear bomb and wiping out 60 million trees.
Scientists tracking the asteroid, currently halfway between Earth and Mars, initially put the odds of impact at 1 in 350 but increased the chances this week. Scientists expect the odds to diminish again early next month after getting new observations of the asteroid's orbit, Chesley said.
"We know that it's going to fly by Mars and most likely going to miss, but there's a possibility of an impact," he said.
If the asteroid does smash into Mars, it will probably hit near the equator close to where the rover Opportunity has been exploring the Martian plains since 2004. The robot is not in danger because it lies outside the impact zone. Speeding at 8 miles a second, a collision would carve a hole the size of the famed Meteor Crater in Arizona.
In 2004, fragments of the comet Shoemaker-Levy 9 smacked into Jupiter, creating a series of overlapping fireballs in space. Astronomers have yet to witness an asteroid impact with another planet.
"Unlike an Earth impact, we're not afraid, but we're excited," Chesley said.
Target Mars—Lucky Us!
Hmmm ... which is the larger target?
Astronomers are hoping for an asteroid impact on January 30, giving them a chance to witness for the first time ever this rare celestial spectacle. But consider this, if the same time frame and odds regarded a collision with our planet and not Mars, they would be in a state of mild panic.
We would do well to remember too that Mars is a smaller target than Earth, and with only two months' notice, we could do nothing to prevent an impact and could only brace ourselves for a catastrophe the likes of which we have never seen. This will only be the second time we will have the opportunity to observe first hand the effects of a celestial collision. In 1994 a comet hit Jupiter; had it hit us instead, well, that would have been it. We would have been extinct for going on fourteen years now—toasted like the dinosaurs.
So, while an impact on our smaller, closer neighbour may be one of the most exciting astronomical shows ever seen, we should also take it as a wake up call. Whether it strikes or not, we can no longer afford to be complacent.
Mars has been hit before
(Image from Mars Express spacecraft)
Asteroid 2007 WD5 is approximately 50 meters wide, about the same size as the rock involved in the 1908 Siberian Tunguska event that flattened an area the size of greater London (2000 square kilometers). Mars has a thinner atmosphere, and should the meteor strike the red planet, it is expected to create an impact crater almost a kilometer wide.
As more physical evidence accumulates, the more we should sit up and take notice before it is too late. We could be next.