An asteroid slamming into Earth's moon tends to see most of its materials ripped off as it crashes into the surface. But Vesta's weak gravity compared to the moon, and lower relative velocity with respect to the asteroids hitting it, makes impacts happen more slowly.
The dark asteroid materials we see scattered on Vesta's bright basalt surface could have implications for how life got started on the Earth. McCord cited a long-standing theory that the Earth's water and organic material could have come from asteroids or comets elsewhere in the solar system.
"We have, apparently, a dramatic example of the surface of an object being contaminated by material from other objects," McCord said of Vesta. "It forces one to (suppose) most objects are contaminated this way, and this is the way the Earth got its water and organic material. It not only has implications for the surface of Vesta, but for most other airless inter-solar system objects."
No Space Weathering Found
In a separate paper published in the same issue of Nature, researchers examined why "space weathering" from solar and cosmic radiation, as well as micrometeroid impacts, is not seen on the surface of Vesta. McCord was a co-author of the study, which was led by Brown University's Carle Pieters.