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Dawn on Vesta

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NASA Dawn spacecraft's view of asteroid Vesta: July 23, 2011

The first close up views of an asteroid (Vesta) taken by NASA’s Dawn spacecraft during its fly past on July 23, 2011. A nice background article from Nature informs:

Planetary scientists thought they knew what to expect when NASA’s Dawn spacecraft returned the first close-up portrait of the giant asteroid Vesta last month. Fuzzy images from the Hubble Space Telescope (HST) taken in 1996 seemed to show that something had taken a big bite out of the asteroid’s south polar region.

New, sharper, images and spectra will help, as will maps of the asteroid’s gravity. Dawn is now orbiting Vesta at a distance of about 2,700 kilometres, some six times closer than when the initial observations were made last month.

The task force will use the data gathered from this closer approach to hunt for evidence of whether the hole really was caused by some sort of collision. Tell-tale signs would include rock that has melted and resolidified on the floor of the depression, and a mixture of broken rock and melted material splashed out of the hole by the force of the blow.

One idea is that Vesta, which, at 530 kilometres across is the second-largest asteroid in the Solar System, was struck not at its south pole but midway between the pole and the equator. Because it spins rapidly, completing a full rotation in about five hours, Vesta would have reoriented itself so that the gouged-out region became the rock’s new south pole.

This would be the most stable configuration for the damaged asteroid, says Schenk. “I don’t think we’ve ever seen before a body with such a large impact and such a high rotation rate,” he says.


Written by Arhopala Bazaloides

August 14, 2011 at 9:04 am

Posted in science, space

Tagged with , , ,

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