Later this year, Mars is going to have a close encounter with a comet. On Oct. 19, 2014, Comet Siding Spring (C/2013 A1) will buzz the Red Planet about 10 times closer than any known comet has ever flown past Earth. Mars could actually find itself inside the comet’s extended atmosphere as the comet passes by only 138,000 km away. Needless to say, NASA is watching carefully.
The image, captured on March 11th, shows comet Siding Spring at a distance of 353 million miles from Earth. Hubble can’t see the icy nucleus because it is hidden inside the comet’s glowing dusty atmosphere. Nevertheless, image processing did reveal what appears to be two jets of dust coming off the nucleus in opposite directions. This observation allows astronomers to calculate the direction of the nucleus’s pole, and axis of rotation.
“This is critical information that we need to determine whether, and to what degree, dust grains in the [atmosphere] of the comet will impact Mars and spacecraft orbiting Mars,” says Jian-Yang Li of the Planetary Science Institute in Tucson, Arizona.
Indeed, meteoroids from the comet could hit NASA’s Mars orbiters and damage them even as the orbiters try to study the comet. The level of risk won’t be known for months, but NASA is already evaluating possible precautionary measures. Data from Hubble and other observatories in the months ahead will clarify the dangers. Stay tuned for full coverage.