Enormous Comet Impact into Mars Less Likely, Says NASA

The enormous comet C/2013 A1, also called Sliding Spring, that is on a near-collision course with Mars is after all very unlikely to hit when it closely approaches the Red Planet later in 2014, NASA's Jet Propulsion Laboratory said in an update.

The comet will reportedly come within about 110,000 kilometers of Mars, but officials say that there is now only a one in 120,000 chance that the comet will strike the planet, compared to the one in 8000 odds reported before.

Siding Spring is from the outer Oort cloud, and will have taken a million years or more to reach the this point. NASA's excited about the comet, even without a collision, because it likely has a cloud of volatile gases absent from comets with shorter periods, those that frequently come near to the sun.

Astronomers' projections have the comet at a near miss with the Martian surface at 11:50 a.m. PST on Oct. 19, 2014.

A NASA release from last month said that if the comet were to hit Mars, the power of the impact would be equivalent to 35 million megatons of TNT.

Officials are uncertain whether the two rovers on the Martian surface will be able to capture images of the comet, especially because they are engineered to look down at the Martin dirt, not up into space. 

"The issue with the Opportunity and Curiosity rovers will be power for imaging at night," said Jim Bell, a planetary scientist and Mars imaging specialist at Arizona State University. "Opportunity is solar powered and so would need to dip into reserve battery power to operate the cameras at night. Whether or not we will be able to do this will depend on how much power the rover is getting from dusty solar panels in the daytime. On the other hand, Curiosity is nuclear powered, so it could have better odds at night-time imaging."