As Comet Nears Mars, NASA Gears Up for Epic Encounter
A comet will give Mars a historically close shave next weekend, and NASA aims to be ready for the dramatic cosmic event. The space agency has already trained a number of its science assets onComet Siding Spring, which will zoom within 87,000 miles (139,500 kilometers) of Mars on Oct. 19 — about one-third the distance between Earth and the moon.