NASA is going to purposely crash both of its Gravity Recovery and Interior Laboratory (GRAIL) Spacecraft into a mountain on the Moon Dec. 17. For science. The controlled impact is a send off of sorts, as the crafts, which have been in polar orbit around the Moon since September 2011, are no longer needed to collect data.
The GRAIL have been utilized to map lunar gravitational anomalies by orbiting the Moon as low as 6.8 miles, helping to create a high resolution gravity map ever. But the two (named Ebb and Flow) are running out of fuel, and since a return trip home is out of the question, NASA intends on sending commands to the two crafts tonight for the kamikaze mission. Their estimated impact speed will be almost 4,000 mph.
“Our lunar twins may be in the twilight of their operational lives, but one thing is for sure, they are going down swinging,” said GRAIL project manager David Lehman of NASA’s Jet Propulsion Laboratory in Pasadena. “Even during the last half of their last orbit, we are going to do an engineering experiment that could help future missions operate more efficiently.”
Unfortunately, because the impact is happening during a new moon, NASA will be unable to take images. The impact site was apparently chosen to avoid interfering with previous American and Russian spacecraft that have landed on the surface.