PASADENA, Calif. (AP) A pair of NASA spacecraft tumbled out of orbit around the moon and crashed back-to-back into the surface on Monday, ending a mission that peered into the lunar interior.

Engineers commanded the twin spacecraft, Ebb and Flow, to fire their engines and burn their remaining fuel. Ebb plunged first, slamming into a mountain near the moon's north pole. Its twin, Flow, followed about a half minute later and aimed for the same target.

By design, the final resting place was far away from the Apollo landing sites and other historical spots on the moon.

After the double impacts, mission chief scientist Maria Zuber of the Massachusetts Institute of Technology said the spot has been named after team member Sally Ride, the first American woman in space, who died earlier this year.

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"It's really cool to know that when you look up now at the moon there's this little corner of the moon that's named after Sally," said Ride's sister, Rev. Bear Ride, adding that she hoped schoolchildren will be inspired.

Since the crash site was in darkness, the final act was not visible from Earth. The Lunar Reconnaissance Orbiter circling the moon will pass over the mountain and attempt to photograph the skid marks left by the washing machine sized-spacecraft as they hit the surface at 3,800 mph.

After rocketing off the launch pad in September 2011, Ebb and Flow took a roundabout journey to the moon, arriving over the New Year's holiday on a gravity-mapping mission.

More than 100 missions have been flung to Earth's nearest neighbor since the dawn of the Space Age including NASA's six Apollo moon landings that put 12 astronauts on the surface.

The demise of Ebb and Flow comes on the same month as the 40th launch anniversary of Apollo 17, the last manned mission to the moon.

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Twin NASA spacecraft deliberately crash into moon