Comet ISON to sweep closely past Mars today 1 October 2013 NASA and ESA are readying a flotilla of spacecraft that will attempt to record the comet’s passage near Mars. On Tuesday (October 1, 2013), this year’s most anticipated comet – Comet ISON – will sweep closely past the Red Planet Mars. It’ll be on its way to a Thanksgiving Day (November 28) encounter with the sun, and hopefully to a good showing in Earth’s night sky. Right now, amateur astronomers with telescopes and photographic equipment are the main ones capturing images of Comet ISON. And they are sure to be trying already to captured Mars and the comet in the same photo in the predawn sky. But NASA and ESA are also readying a flotilla of spacecraft in Mars orbit or on Mars’ surface, which will attempt to record the comet’s passage near Earth’s neighboring planet. And we do mean near. On October 1, Comet ISON will pass within 0.07 AU from Mars. That’s about six times closer than the comet will ever come to Earth. NASA says an “unprecedented” number of NASA spacecraft – 16 – plus astronauts aboard the International Space Station will be observing the comet. Mars rovers and satellites – including Mars Express, Mars Reconnaissance Orbiter and rovers on the planet’s surface – might get a close-up view. We say might because it’s not certain yet just how good a view the rovers will get, at the comet’s current brightness. ISON is fainter than anticipated when it was discovered in late 2012. But recent photos show a greenish color to the comet, a sign that the comet has crossed the “frost line,” a place outside Mars’ orbit where solar heating is enough to start vaporizing ices on ISON’s surfaces. NASA scientists said earlier this year they believe the best bet for capturing great views of Comet ISON during its Mars passage will be NASA’s Mars Reconnaissance Orbiter. The MRO satellite is equipped with a powerful half-meter telescope (called HiRISE) that will be able to detect the comet’s atmosphere and tail. Scientists hope this spacecraft, or one of the others, or all of them combined, will enable them to learn how large Comet ISON’s nucleus is. Astronomer Carey Lisse of the Johns Hopkins University Applied Physics Lab explained the reason for the fascination with ISON’s nucleus: If ISON’s nucleus is much bigger than 0.5 km, it will probably survive its Thanksgiving Day brush with the sun. And an intact nucleus could mean a bright comet in the skies visible from Earth in early December.
Posted on: Tue, 01 Oct 2013 18:50:52 +0000
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