Asteroid To Collide With Mars?

Astronomers have calculated that a recently discovered asteroid named 2007 WD5 which is about 100 meters in diameter, is heading towards Mars and has a 1 in 75 chance of impact. The collision with the Red Planet could occur on January 30 according to the scientists.

The asteroid is currently halfway between Earth and Mars and moving with a velocity of 8 miles per second. Scientists who are tracking its path had initially put the odds of impact at 1 in 350 but increased the chances this week. The odds are expected to decline further, early next month after new observations of the asteroid’s orbit are obtained by the scientists.

“These odds are extremely unusual,” said Steve Chesley, an astronomer with the Near Earth Object Program at NASA's Jet Propulsion Laboratory in Pasadena, California. “We frequently work with really long odds when we track threatening asteroids. We know that it's going to fly by Mars and most likely going to miss, but there's a possibility of an impact.”

This probable collision presents a very rare opportunity for astronomers to study the effects of such impacts as astronomers have yet to witness an asteroid impact with another planet. Chesley said, “Unlike an Earth impact, we’re not afraid, but we’re excited.”

The asteroid is broadly similar in size to the one that hit Tunguska in Siberia in 1908. That impact unleashed energy equivalent to an explosion of 10-20 million tons of TNT and wiping out 60 million trees spread over 810 square miles. In comparison, the impact from 2007 WD5 is likely to be smaller-about as much as 3 million tons of TNT according to Chesley.

If the asteroid does collide with Mars, the impact is expected to occur near the equator close to where the rover Opportunity has been exploring the Martian plains since 2004. The robot though is not in any danger because it lies outside the impact zone. The impact can form a crater of the same size as of the famed Meteor Crater in Arizona.

The Near Earth Object team routinely scans the skies for asteroids approaching our planet. 2007 WD5 passed earth 4.3 million miles away on Nov. 1 and was spotted three weeks later through a telescope in Arizona.

Conducting a routine check to determine whether the asteroid would pass Earth again in the next 100 years, Chesley noticed the asteroid could be on track to hit Mars. "As soon as I saw that this was going to have a very close approach to Mars and might even hit, I immediately started calling the other observatories," he said.

Chesley confirmed the close approach after fine-tuning the asteroid’s path by observing it for the fifth time on Tuesday which was delayed by inclement weather and snowbound observatories.

Still, there isn't enough data to know whether 2007 WD5 will smash into Mars, or pass more than 400,000 miles away from the planet. Chesley said, "It's important to emphasize that it's pretty near 99 percent that it's going to miss."

More information about the asteroid’s future will be obtained in early January only because the asteroid is rushing farther and farther from Earth and getting obscured by the coming full moon.

The probable impact would just be barely visible from the largest of Earth's observatories, but its effects would readily be seen by probes orbiting the Red Planet such as the European Space Agency's Mars Express. It will not be visible with domestic telescopes or the naked eye.

The fact that Mars is currently very close to Earth has improved the chances of observing an impact using large terrestrial telescopes. On Tuesday, the planet was just 55 million miles away, the closest it will be until 2016.