Mission Over: Twin Moon Probes Crashed into Lunar Mountain

摘要

NASA's pair of twin gravity-mapping lunar probes ended their science mission Dec. 17 by slamming into a crater rim near the Moon's north pole. The pair of washer-and-dryer-sized Grail spacecraft were crashed intentionally because their low orbit and remaining fuel levels precluded further scientific operations.The impacts, which were directed by earlier rocket burns, were designed to keep the two probes from colliding with historic sites on the surface of the Moon.