Scientists at NASA Ames Research Center announced on Thursday that the Lunar Atmosphere and Dust Environment Explorer (LADEE) will begin lowering its orbital altitude later this month to make further scientific observations before its planned impact into the moon's surface on or before April 21. Ground controllers at Ames will bring the spacecraft as low as 1 to 2 miles above the lunar surface to gather data.
A final maneuver will take the spacecraft into a trajectory that will cause it to impact the surface on the far side of the moon. This will ensure that the spacecraft does not impact near any previous lunar landing sites. Because maneuvering at such low altitudes can be tricky, the controllers will not attempt to bring LADEE down at any particular spot.
"The moon's gravity field is so lumpy, and the terrain is so highly variable with crater ridges and valleys that frequent maneuvers are required or the LADEE spacecraft will impact the moon’s surface," said Butler Hine, LADEE project manager at Ames. "Even if we perform all maneuvers perfectly, there's still a chance LADEE could impact the moon sometime before April 21, which is when we expect LADEE's orbit to naturally decay after using all the fuel onboard."
LADEE may be affected by a total lunar eclipse which will occur on April 15. The four-hour eclipse will expose the spacecraft to extreme cold and test the limits of the spacecraft's design.
"If LADEE survives the eclipse, we will have nearly a week of additional science at low altitudes before impact," said Rick Elphic, LADEE project scientist at Ames. "For a short mission like LADEE, even a few days count for a lot – this is a very exciting time in the mission."
NASA has created a "Take the Plunge Challenge" where members of the public give their guesses of when LADEE will impact the lunar surface. Anyone is eligible to enter. Winners will be announced after impact and will be e-mailed a commemorative, personalized certificate from the LADEE program. The submissions deadline is 3 p.m. PDT Friday, April 11.
LADEE was launched from NASA Wallops Island Launch Facility on Sept. 6, 2013. The spacecraft has been in lunar orbit since Oct. 10, 2013. In addition to studying the moon's extremely thin atmosphere and the properties of lunar dust, LADEE successfully tested a laser-based communications system.