NASA has rerouted its Mars orbiters to be in the best position to watch Comet Siding Spring's close encounter with the Red Planet on Oct. 19 while avoiding potentially damaging fallout. "All our spacecraft will be on the opposite side of the planet" when Mars goes through the comet's dust tail, Jim Green, director of NASA's Planetary Science Division, said Thursday during a televised news briefing.

The Oort Cloud comet is due to come within 88,000 miles (138,000) kilometers of Mars during its first-ever trip through the inner solar system. "It's closer than any comet has come to Earth in the last 500 years," said Carey Lisse, senior astrophysicist at John Hopkins University Applied Physics Laboratory. The comet is thought to be made up of fluffy stuff from the solar system's early days.

More than a dozen space probes— ranging from NASA's Mars rovers to the Hubble Space Telescope — will be gathering data during the comet's closest approach to Mars at 2:27 p.m. ET Oct. 19. The dust tail should stream past about 100 minutes later.

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Yanamandra-Fisher: PACA project @ProAmAstronomy has a Flickr pool for Siding Spring photos: https://t.co/DWp5HofxS6 pic.twitter.com/8h8XJbirlD — Emily Lakdawalla (@elakdawalla) October 9, 2014

Exciting times with less than 2-weeks to close approach, but there are caveats... http://t.co/toPLjEu7tq #MarsComet — Karl Battams (@SungrazerComets) October 6, 2014

— Alan Boyle