According to NASA the comet discovered earlier this year should pass at a distance of less than 100,000 (one hundred thousand) kilometers from our neighboring planet. NASA scientists say the large comet could even collide with the red planet in October of 2014. The chance is not high—roughly 1 in 2000. But if the comet at 50 kilometers in diameter hit Mars it would leave a 500-hundred kilometer crater.
Such a comet striking earth would be a global disaster, but on Mars it makes an interesting science experiment. Scientists will know one way or the other in a few months We'll keep you posted.