An artist’s impression of the LADEE spacecraft in orbit above the moon as dust scatters light during the lunar sunset (Image: NASA Ames/Dana Berry)

Update: NASA reports that the probe has crashed into the lunar far side, making impact on 17 April sometime between 4.30 and 7.22 pm UTC. Read the latest story here (published 1741 GMT 18 April 2014).

NASA is about to order a spacecraft orbiting the moon to self-destruct. Next week, mission managers will send a signal to the LADEE probe telling it to shut down and get ready to crash into the lunar surface.

LADEE launched from Wallops Island, Virginia, on 6 September 2013 and settled into lunar orbit about a month later. The mission’s goals were few and specific: test a broadband communications system between Earth and the moon; analyse the moon’s thin atmosphere; and investigate the cause of a strange pre-sunrise glow seen by some Apollo moonwalkers.


The spacecraft’s main mission ended in early March, and it will soon run out of the fuel needed to keep it in orbit. Since LADEE cannot come home, NASA will intentionally crash the probe into the far side of the moon, away from historically important sites like the Apollo landing zones.

Mission managers will send the orbiter a signal to turn off all its science instruments on 11 April and set the craft on course for a crash landing. But the moon’s gravity field is very uneven, and variations in the field will affect LADEE’s path as it descends. That means no one is certain exactly when or where on the far side it will crash, just that it should happen sometime before 21 April. NASA is holding a contest to guess the precise spot where LADEE will meet its fate. The resulting crater should be visible to the Lunar Reconnaissance Orbiter in the coming months.

Netflix on the moon

Although the mission was relatively brief, LADEE was highly productive. The laser-based communication system worked wonderfully, says team member Mihaly Horanyi at the University of Colorado, Boulder.

“We had a really high rate of data transmission. You could have watched Netflix on the moon if you wanted to,” he says. Future versions of this technology could stream high-definition video from space probes or from human missions into deep space.

The LADEE team also found that the moon is engulfed in a cloud of dust that is being constantly refreshed by impacts from micrometeorites. “People expected this, but this is the first time we’ve actually made measurements,” says Horanyi. Similar small impacts should churn up dust on other rocky bodies in the solar system, so studying the size distribution of the lunar particles could help in planning for future missions to an asteroid or Mars.

Astronaut moonbeams

However, the team is still not sure what caused the mysterious lunar rays seen by Apollo astronauts. The best theory is that solar radiation gives some particles of fine, glassy moon soil a positive charge, which repels the grains upwards. Gravity pulls those grains back down even as new particles float up, creating fountains of electrostatic dust that would reflect light. The effect should be stronger at twilight, which is when astronauts reported the lunar beams.

The dust particles involved would be too small for LADEE’s instruments to see directly, but the craft was able to look for the electrical current that should be coursing through such dust fountains. However, the current they saw was two orders of magnitude too low to account for the Apollo astronaut’s horizon glow. LADEE could yet see evidence of the dust fountains in its last week of operation, as it spirals closer to the lunar surface. But for now, mission managers are prepared for the craft’s bittersweet farewell.

“It delivered what it was supposed to,” says Horanyi. “Unfortunately, all good things come to an end.”