Currently, NASA has two observation craft circling the Martian planet. A third will arrive just a month prior to the arrival of Comet C/2013 A1.
"Three expert teams have modeled this comet for NASA and provided forecasts for its flyby of Mars," explained Rich Zurek, chief scientist for the Mars Exploration Program at NASA's Jet Propulsion Laboratory. "The hazard is not an impact of the comet nucleus, but the trail of debris coming from it."
Though the risk isn't as great as once thought, even the tiniest pieces of debris -- which will be spewed from the passing comet at a rate of 35 miles per second -- could do serious damage to one of the three orbiters.
"Mars will be right at the edge of the debris cloud, so it might encounter some of the particles -- or it might not," said Zurek.
NASA will make slight adjustments to the orbiter's path to minimize the risk of the comet's debris hitting the spacecraft. But the three probes will still be in prime position to capture hopefully impressive footage of the flyby. The comet will pass Mars at one-tenth the closest distance a comet has ever come to Earth.
MAVEN now orbiting Mars