A NASA spacecraft that studied lunar dust vaporized into its own cloud of dust when it hit the Moon, as planned, in a mission-ending impact on 17 April. Launched last September, the Lunar Atmosphere and Dust Environment Explorer (LADEE) finished its primary mission in March. In early April, on an extended mission, it made close passes as low as 2 kilometres above the surface, gathering data on more than 100 low-elevation orbits. Mission controllers deliberately crashed it to avoid the chance that, left alone, it might crash and contaminate historic locations such as the Apollo landing sites.
During its lifetime, LADEE made the best measurements yet of the dust generated when tiny meteorites bombard the surface. It is still hunting the mystery of a horizon glow seen by Apollo astronauts. It also carried a test for future laser communications between spacecraft and Earth.
In its final days the probe unexpectedly survived the cold and dark of a total lunar eclipse on 15 April. Just before the eclipse, NASA had the spacecraft perform a final engine burn that determined the crash trajectory. LADEE normally coped with just one hour of darkness every time it looped behind the Moon. The eclipse put it into darkness for some four hours, potentially jeopardizing the ability of its battery-powered heaters to keep the spacecraft from freezing to death. But the spacecraft survived.
NASA has been running a contest to predict the exact date and time of the LADEE impact, and this morning predicted there may be multiple winners. When it hit, the probe was travelling about three times as fast as a rifle bullet. In the coming months the Lunar Reconnaissance Orbiter will take pictures of the crash site, which engineers are still determining.