For science buffs: comet close to Mars

http://www.bbc.com/news/science-environment-29665247

Comet Buzzes Mars in Once-in-a-Lifetime Flyby
SPACE.com By by Mike Wall, Senior Writer
7 hours ago
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Comet Buzzes Mars in Once-in-a-Lifetime Flyby

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A comet zoomed by Mars today (Oct. 19) in an extremely rare close encounter that scientists billed as a "once-in-a-lifetime" event that may help researchers better understand the earliest days of our solar system.

Comet Flies By Mars Today in Rare Encounter: Watch It Online SPACE.com
Rare comet fly-by of Mars on Sunday AFP
Comet Siding Spring came within just 87,000 miles (139,500 kilometers) of the Martian surface at 2:27 p.m. EDT (1827 GMT) today — about one-third of the distance between Earth and the moon. At the time of closest approach, the comet barreled by at 126,000 mph (203,000 km/h) relative to the Red Planet, NASA officials said.

All seven spacecraft currently operating on or around Mars were scheduled to observe the close shave, with the aim of learning more about comet composition and behavior. [See photos of Comet Siding Spring]

"We cannot plan missions to comets like this — this one was discovered less than two years ago. It is incredible luck that it is saving us the trouble of going to it, as it flies by Mars, which is being explored by seven active robots," Mark Lemmon of Texas A&M University, a camera team member for NASA's Curiosity and Opportunity Mars rovers, said in a statement. "So this very much is a once-in-a-lifetime event, for us and our rovers."

Planetary scientist David Grinspoon, who tracked Comet Siding Spring flyby in real-time during a live webcast by the Slooh Community Observatory, compared the significance of the event with the epic impact of Comet Shoemaker-Levy 9 with Jupiter in 1994.