An eagle-eyed NASA spacecraft has spotted the tiny craters two moon probes created when they crashed intentionally into the lunar surface last year.

NASA's Lunar Reconnaissance Orbiter (LRO) snapped a series of photographs of the two 16.5-foot-wide (5 meters) craters, which mark where the space agency'stwin Grail probesended their gravity-mapping mission, and their operational lives, on Dec. 17.

"It was really fun to find the craters," Mark Robinson of Arizona State University, principal investigator for the Lunar Reconnaissance Orbiter Camera (LROC), said today (March 19) during a press conference at the 44th Lunar and Planetary Science Conference in The Woodlands, Texas.

It's a bit of a surprise that the LROC team was able to find the craters at all, Robinson added. LRO orbits the moon at an altitude of about 100 miles (160 kilometers), and the craters are small, nondescript features on a body riddled with impact scars. [Grail Probes' Final Moments (Video)]

The two Grail spacecraft known as Ebb and Flow slammed into a mountain near the lunar north pole at 3,771 mph (6,070 km/h), striking the lunar surface about 20 seconds apart. They were running out of fuel and were bound to crash at some point, so the Grail team brought them down in a controlled fashion away from areas of historical importance such as the Apollo landing sites.

The Grail craters first showed up in LROC photos from January, but images taken on Feb. 28 show them in much greater detail. Robinson and his team used these later photos to produce a topographic map of the impact zone, which was named after the late NASA astronaut Sally Ride,who had led Grail's educational MoonKAM project before her death last July.

This map revealed that the two craters are separated by about 7,250 feet (2,210 m) in straight-line distance and 985 feet (300 m) in altitude, researchers said. Surprisingly, the crashes ejected material that appears darker than the surrounding lunar dirt.

"Fresh impact craters on the moon are typically bright, but these may be dark due to spacecraft material being mixed with the ejecta," Robinson said in a statement. This material may be residual fuel left in the probes' lines, or bits of their carbon-fiber bodies, he added.

LRO also managed to observe the immediate aftermath of the Dec. 17 Grail impacts after performing some precision maneuvering, team members announced today.

LRO didn't get any images of the actual crashes, which occurred in the dark. But its ultraviolet imaging spectrograph did see emissions from mercury and atomic hydrogen in the ejected plumes when they rose high enough to reach sunlight.

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Graves of Twin Moon Probes Spotted by NASA Spacecraft