Spacecraft images of asteroid reinforce telescope observations

NASA scientists say a spacecraft's close-up view of an asteroid can work with ground-based telescopes to clarify our understanding of a solar system object. The agency's Dawn spacecraft that studied the giant asteroid Vesta from July 2011 to September 2012 captured images that provided a "reality check" for images taken by ground-based telescopes and the Hubble Space Telescope, they said. "Since the vast majority of asteroids can only be studied remotely by ground-based and space-based facilities, confirming the accuracy of such observations using in-situ measurements is important to our exploration of the solar system," Vishnu Reddy of the Planetary Science Institute in Tucson, Ariz., said. The up-close observations of Vesta have confirmed and provided new insights into more than 200 years of Earth-based observations, researchers said. "A generation of scientific questions framed on the basis of lower-resolution data have been resolved by visiting Vesta with Dawn," Dawn Principal Investigator Christopher Russell, at the University of California, Los Angeles, said. "We chose to go to Vesta because the ground-based telescopes and, later, Hubble told us it was an interesting place." The hints from Hubble proved to be true, researchers said, as amply demonstrated by Dawn's camera. "When Dawn got to Vesta, it showed us how accurate Hubble's data were about Vesta," Planetary Science Institute research scientist Jian-Yang Li said. "And it also showed us how Vesta was so much more interesting up-close."