PROVIDENCE, R.I. [Brown University] — The surface of the giant
asteroid Vesta is weathering in a way that appears to be
completely different from any other asteroid yet visited,
according to new data recorded by NASA's Dawn spacecraft. This
new type of space weathering suggests that there's something
about Vesta — perhaps its mineral composition or its position in
the solar system — that makes its surface environment
fundamentally different from other asteroids studied thus far.
The new data are presented in a paper published Nov. 1, 2012, in
the journal Nature. Space weathering is the term used to
describe how the surfaces of airless bodies like asteroids and
some moons change over time. The phenomenon was first identified
on our own Moon. Soil ejected from fresh impact craters looks
brighter than the surrounding background soil, often forming
bright rays streaming away from the crater. It wasn't clear at
first why newly exposed soil would look different. As laboratory
equipment improved, scientists eventual