This spring, NASA will be paying cautious attention to a comet that could put on a barnstorming show at Mars on Oct. 19, 2014.
On that date, comet C/2013 A1 Siding Spring will buzz Mars about 10 times closer than any identified comet has ever flown past Earth.
Spacecraft at Mars might get a good look at the nucleus of comet Siding Spring as it heads toward the closest approach, roughly 86,000 miles (138,000 kilometers) from the planet, give or take a few percent. On the other hand, dust particles that the comet nucleus sheds this spring could threaten orbiting spacecraft at Mars in October.
The level of risk won’t be known for months, but NASA is already evaluating possible precautionary measures as it prepares for studying the comet.
“Our plans for using spacecraft at Mars to observe comet Siding Spring will be coordinated with plans for how the orbiters will duck and cover, if we need to do that,” said Rich Zurek, Mars Exploration Program chief scientist at NASA’s Jet Propulsion Laboratory, Pasadena, Calif.
Comet Siding Spring, formally named C/2013 A1, was discovered on Jan. 3, 2013, from Australia’s Siding Spring Observatory. At the time, it was farther from the Sun than Jupiter is. Subsequent observations enabled scientists at JPL and elsewhere to calculate the trajectory the comet will follow as it swings past Mars. Observations in 2014 will continue to refine knowledge of the comet’s path, but in approximate terms, Siding Spring’s nucleus will come about as close to Mars as one-third of the distance between Earth and the Moon.