ScienceShot: Asteroid Vesta Emerges

Dick writes about Earth and planetary science for Science magazine.

With NASA's release today of the latest image from the approaching Dawn spacecraft, asteroid Vesta is no longer a fuzzy, nearly featureless ball; it's a surprisingly youthful world, geologically speaking, sporting still-mysterious features. Although Dawn will go into close orbit around 529-kilometer-diameter Vesta this weekend, the newly-released image of the asteroid—taken 9 July from a distance of 41,000 kilometers—already reveals never-before-seen detail that has planetary scientists scratching their heads. Hubble Space Telescope had already revealed the peak or mound in the left-center; it marks the heart of an enormous impact crater spanning 460 kilometers (apparently hard to see from this perspective). But there are also roughly parallel ridges, grooves, or who knows what that swirl across the lower part of the image. And then there is what's missing: innumerable smaller impact craters accumulated over the eons. Dawn's year-long visit could show whether the humongous impact obliterated them as it wiped Vesta's geological slate clean.

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Posted in Space