WATCH: NASA crashes twin probes into the moon

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(CNN) – A pair of robotic twins that have been diligently mapping the moon this year went out with a bang Monday. 

The Gravity Recovery and Interior Laboratory (GRAIL) probes, Ebb and Flow, crashed into a mountain on the moon Monday afternoon.

It ended a fruitful mission to study the surface and composition of the moon.

NASA crashed the probes, about the size of an apartment washer and dryer, because they’re running out of fuel.

The twin spacecraft hit intentionally near the moon’s north pole at 4:28 p.m. CST.

NASA says thanks to GRAIL, scientists now have the highest-resolution gravity field map of any celestial body and the probes have given scientists unprecedented insight into what’s below the surface and how the moon may have formed.