Two NASA Moon orbiters that have been studying the rock's gravity field will crash into our natural satellite on Monday. NASA actually meant to do this and this will be a controlled crash.
Ebb and Flow, as the two probes have been named, have been orbiting the Moon since the 1st of January this year and have ended their mission.
Their low orbit and small fuel reserves mean that they have no more scientific usefulness and they would eventually deorbit and crash into the Moon anyway. They have completed the most accurate gravity map of any planetary body, to date.
They do have one final mission before they meet their maker, they will fire up their engine and keep them running until they run out of fuel.
NASA wants to measure how much fuel they have left to perfect fuel consumption simulations for future missions.
The location for their final resting place has been chosen, a mountain near the Goldschmidt crater. Though, hitting at 3,760 mph, 6,051 km/h or 1.7 km per second, there won't be much left of the spacecraft after they crash.