Twin spacecraft by US space agency NASA that have been orbiting the moon and allowing scientists to learn more about the moon’s composition and internal structure are to crash land on the moon’s surface today at 1.7 kilometres per second (3,760mph).
NASA has been preparing the probes, Ebb and Flow, for their controlled descent and impact on a mountain near the moon’s north pole at about 2.28pm PST (5.28pm EST, 10.28pm GMT) today.
Ebb and Flow, the Gravity Recovery and Interior Laboratory (GRAIL) mission probes, are being sent purposely into the lunar surface because their low orbit and low fuel levels preclude further scientific operations, NASA said.
The probes have generated the highest resolution gravity field map of any celestial body, NASA added. That map will provide a better understanding of how Earth and other rocky planets in the solar system formed and evolved.
“It is going to be difficult to say goodbye,” said GRAIL principal investigator Maria Zuber of the Massachusetts Institute of Technology in Cambridge.
“Our little robotic twins have been exemplary members of the GRAIL family, and planetary science has advanced in a major way because of their contributions.”
Both spacecraft have been flying in formation around the moon since 1 January of this year.
The first probe to reach the moon, Ebb, will be the first to go down. Flow will follow about 20 seconds later, said NASA.
No images of the impact are expected because the region of impact will be in shadow at the time.