NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE) was always planned to be a short mission. And now, after a one-month extension of science activities, the LADEE team announced on Thursday that the mission would end sometime on April 21st, 2014.
"[LADEE] over-achieved all of our expectations for it," said Joan Salute, LADEE program executive at NASA Headquarters. She went on to say that all of the mission's primary science goals were met in early March.
The mission will continue to gather science data on the Moon's tenuous exosphere for the next few weeks. On April 5th, around midnight Pacific time, LADEE will execute an engine burn to bring her closer to the surface of the moon than ever before, skimming past peaks of lunar mountain ranges, missing them, at times, by just a few kilometers.
In past experience, lunar missions have discovered new science close to the surface of the Moon, previously unobtainable at higher altitudes. "We're expecting to see new things," said LADEE Project Scientist Rick Elphic of NASA's Ames Research Center.
LADEE will climb back out of its close orbit after a week, and will seal its fate with a final engine burn on April 11th. The resulting orbit will cause LADEE to impact on the far side of the Moon sometime on April 21st. Due to to the Moon's lumpy gravitational field, the team does not know exactly when LADEE will crash. NASA is having fun with this uncertainty, allowing the public the submit their best guess for when LADEE will actually impact in their Take the Plunge challenge.
LADEE is being crashed onto the far side of the Moon in order to remove any threats to the historic Apollo landing sites (all of which are on the Earth-facing side of the Moon). Since LADEE will fly through an eclipse on April 15th which could freeze parts of its propulsion system, the team took no chances, selecting an orbit beforehand that would terminate LADEE without further engine burns.
The team will eventually know the time of impact. After LADEE fails to appear after passing back behind the Moon, the team will crunch the numbers for its last-known telemetry data to determine when and where the spacecraft crashed, a process which takes about 12 hours. The Lunar Reconnaissance Orbiter will attempt to image the crash site at some point in the future.