This picture of the Eros asteroid is the first of an asteroid taken from an orbiting spacecraft. The crater at the center is about 4 miles across. JPL/JHUAPL/NASA hide caption

itoggle caption JPL/JHUAPL/NASA

NASA's GRAIL mission to study the moon launches aboard a Delta II rocket at Kennedy Space Center on Sept. 10. Sandra Joseph and Don Kight/NASA hide caption

itoggle caption Sandra Joseph and Don Kight/NASA

This artist's conceptual image shows the Upper Atmosphere Research Satellite, or UARS. After two decades in orbit, the satellite will make an uncontrolled re-entry into the Earth's atmosphere. NASA hide caption

itoggle caption NASA

NASA's Kepler mission has discovered a planet that circles two stars instead of one. The planet, shown as the black dot in this artist's illustration, is similar to Saturn, though it is more dense and travels in a 229-day circular orbit around its two stars. R. Hurt/NASA/JPL-Caltech hide caption

itoggle caption R. Hurt/NASA/JPL-Caltech