NASA will send two decommissioned probes to a crash landing on the moon Monday, punctuating a violent end for a mission which mapped the lunar gravity field with more precision than any other object in the solar system.

Running low on fuel, the GRAIL satellites will aim for a mountain in the northern hemisphere near Goldschmidt crater. Approaching at a shallow angle of about 1.5 degrees, the nearly identical spacecraft will impact with a velocity of about 3,760 mph, excavating