Science Shot: Dawn Spies a Messed-Up Vesta

Dick writes about Earth and planetary science for Science magazine.

Two weeks after settling into orbit around Vesta, the ion-propelled Dawn spacecraft is returning stunning images of the 530-kilometer-wide asteroid. And boy is it in rough shape. An image presented today at a NASA press conference is the first whole-asteroid portrait returned from a distance of 5200 kilometers. The broad, relatively smooth expanse covering much of Vesta in this view is part of the 460-kilometer-wide crater blown into the south pole region when the impact of an 80-kilometer asteroid nearly shattered Vesta. Having been created relatively recently in solar system history, this impact basin has accumulated fewer of the smaller craters that roughen the surface to the north (top of image and in this video). More mysteriously, the region in the north is banded by parallel grooves running like lines of latitude around Vesta's equatorial region. Planetary scientists modeling a huge impact on Vesta had warned that rocky debris could pile up in some odd shapes, but nothing like this showed up in their models. Dawn will be dipping to lower and lower altitudes in coming months until it is just 200 kilometers above the surface.

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Posted in Space