Deep in the heart of the asteroid belt, on its way to the belt's two most massive inhabitants, Vesta and Ceres, NASA's ion-propelled Dawn spacecraft has eclipsed the record for velocity change produced by a spacecraft's engines. The previous standard-bearer for velocity change, NASA's Deep Space 1, also powered by ion propulsion, was the first interplanetary spacecraft to use this technology. The Deep Space 1 record fell on June 5, 2010 when the Dawn spacecraft's accumulated acceleration over the mission exceeded 4.3 kilometers per second (9,600 miles per hour).