NASA Mission Helps Solve a Mystery: Why Are Some Asteroid Surfaces Rocky? Posted on 2021/11/04 by Carl Robitaille NASA Mission Helps Solve a Mystery: Why Are Some Asteroid Surfaces Rocky? Before #OSIRISREx arrived at asteroid Bennu, scientists thought it would be like a sandy beach. Instead they found a surface covered in boulders. But why? Scientists have solved the mystery: https://t.co/nGzAVivnyh pic.twitter.com/GAHqEmfE6F— NASA (@NASA) October 22, 2021