Ground controllers at NASA Ames Research Center announced on Friday, April 18 that the Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft had impacted the lunar surface sometime between 9:30 p.m. and 10:22 p.m. PDT Thursday, April 17. LADEE had successfully completed its primary scientific mission and had entered into an extended low altitude phase of data gathering. Because it lacked sufficient fuel to maintain orbit, controllers intentionally sent the spacecraft into the lunar surface.The planned impact on the far side of the moon came just days after the spacecraft survived a lengthy lunar eclipse.
"At the time of impact, LADEE was traveling at a speed of 3,600 miles per hour – about three times the speed of a high-powered rifle bullet," said Rick Elphic, LADEE project scientist at Ames. "There’s nothing gentle about impact at these speeds – it’s just a question of whether LADEE made a localized craterlet on a hillside or scattered debris across a flat area. It will be interesting to see what kind of feature LADEE has created."
Mission controllers will determine the exact time and location of LADEE's impact and work with NASA's Lunar Reconnaissance Orbiter (LRO) team to capture images of the impact site. LRO was launched in 2009 and orbits the moon studying the lunar surface and taking detailed images.
LADEE was traveling at a speed of 3,600 miles per hour when it impacted the lunar surface. The vending machine sized spacecraft is believed to have broken apart on impact, with most of its material heating up hundreds of degrees or possibly vaporizing. Any remnants of the spacecraft are probably buried in shallow craters.
LADEE was launched from NASA's Wallops Island Flight Facility on Sept. 6, 2013. The spacecraft began its primary science mission on Nov.20, 2013 and started a low-altitude extended science phase in March 2014. During this phase LADEE flew at altitudes as low as 2 miles above the lunar surface.
The LADEE mission faced its biggest challenge during the lunar eclipse of April 14-15. During the four hour eclipse the solar-powered spacecraft lacked the sunlight required to power its systems and heaters and to recharge its batteries. Despite facing extremely cold temperatures, the spacecraft survived and resumed collecting scientific data shortly after the eclipse ended.
LADEE gathered detailed information about the moon's thin atmosphere and properties of lunar dust. The spacecraft also tested the use of lasers for two-way high-speed data communications between the Earth and lunar orbit. The Lunar Laser Communication Demonstration (LLCD) used a pulsed laser beam to transmit data from the moon to the Earth at a record-breaking rate of 622 megabits per second (Mbps).
"LADEE was a mission of firsts, achieving yet another first by successfully flying more than 100 orbits at extremely low altitudes," said Joan Salute, LADEE program executive, at NASA Headquarters in Washington. "Although a risky decision, we're already seeing evidence that the risk was worth taking.”