Earthlings may be treated to a dazzling celestial display this fall as Comet ISON makes a suicidal plunge toward the sun. But spacecraft exploring Mars is poised to get close-up views of the icy wanderer first.
"Comet ISON is paying a visit to the Red Planet," astronomer Carey Lisse of the Johns Hopkins University Applied Physics Lab, said in a statement. "On Oct 1, the comet will pass within 0.07 AU from Mars, about six times closer than it will ever come to Earth."
One AU, or astronomical unit, is the distance between the Earth and sun, about 93 million miles. Comet ISON's Mars flyby, at 0.07 AU, will be about 6.5 million miles.
Comet ISON may brighten enough for NASA's Mars rover Curiosity to see it from the surface of the Red Planet. However, Lisse said the best chance for a Martian sighting lies with the space agency's Mars Reconnaissance Orbiter.
The MRO satellite is equipped with a powerful telescope named HiRISE that is intended to take pictures the Red Planet's surface. But researchers think the instrument will be capable of turning its gaze into space to detect the comet's atmosphere and tail.
"The camera is designed for rapid imaging of Mars," the HiRISE's telescope's principal investigator, Alfred McEwen of the University of Arizona, said in a statement. "Our maximum exposure time is limited compared to detectors on other space telescopes. This is a major limitation for imaging comets. Nevertheless, I think we will detect Comet ISON."
"The science value of observing Comet ISON is hard to predict. We've never tried such a thing before," McEwen said. "However, this is good practice for Comet Siding Spring, which will pass much closer to Mars in 2014."