Monday, July 12, 2010

Rosetta Meets a Stone

Over the weekend, on July 10th at 16:10 GMT, ESA's Rosetta spacecraft flew by 21 Lutetia, an asteroid 454 million km from Earth, the largest asteroid ever visited by a satellite. The spacecraft is on its way to a 2014 rendezvous with comet 67P/Churyumov-Gerasimenko, and on its way it was perfectly lined up to skim by the asteroid. By 'skim' we're talking it passed by at only 3,162 km (1964 mi) away, this at a speed of 54,000 km/hr. During its flyby, Rosetta took data on 21 Lutetia's surface, dust environment, exosphere, magnetic field, mass, and density. It also took some spectacular close-up images (details down to a scale of 60m) using its OSIRIS instrument, a camera that combines wide and narrow angles. The asteroid is shown to have a battered, cratered surface which includes a giant bowl-shaped depression stretching across much of one side of the asteroid. The photos suggest it is a very old object, likely left over from the formation of the solar system. These images also confirm that Lutetia is an elongated body, with its longest side approximately 130 km (80 mi) long. After its minute-long flyby, Rosetta began transmitting data to Earth for analysis, so expect more interesting findings from one of the oldest, close objects we've observed.

(image credit ESA 2010 MPS for OSIRIS Team)
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