WASHINGTON - Twin NASA spacecraft orbiting the moon ended their mission on Monday by crashing into a lunar mountain on purpose, the US space agency NASA announced.

Ebb and Flow, the Gravity Recovery and Interior Laboratory mission probes, were being sent purposely into the lunar surface because their low orbit and low fuel levels preclude further scientific operations. This ensures that they don't end up crashing into the Apollo landing sites or any other place on the moon with special importance.

An artist's depiction shows the twin spacecraft (Ebb and Flow) that comprise NASA's Gravity Recovery And Interior Laboratory (GRAIL) mission. A pair of NASA moon-mapping probes smashed themselves into a lunar mountain on Dec 17, 2012, ending a year-long mission that is shedding light on how the solar system formed. [Photo/Agencies]

According to NASA, both spacecraft hit the lunar surface at 3,760 mph (1.7 kilometers per second). The mountain where the two spacecraft made contact is located near a crater named Goldschmidt near the moon's north pole. The impact site was in shadow at the time of the crash, so no video of Ebb and Flow's violent demise is expected.

The duo have spent almost a year mapping the moon's gravity in unprecedented detail. The map will provide a better understanding of how Earth and other rocky planets in the solar system formed and evolved.