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This composite image released NASA taken by NASA s Lunar Reconnaissance Orbiter shows a region of the moon before and after the twin Grail spacecraft deliberately crashed into in December 2012. The spacecraft called Ebb and Flow mapped the lunar gravity in greater detail than previous missions.
LOS ANGELES—When NASA's twin spacecraft Ebb and Flow crashed into the moon last year, scientists did not count on seeing the aftermath.

On Tuesday, the space agency released before-and-after pictures of the lunar north pole where Ebb and Flow came to rest. Months after the back-to-back, mission-ending dives, the Lunar Reconnaissance Orbiter flew over the crash sites and imaged the final resting spots.

Ebb and Flow broke into smithereens upon impact and pinpointing the small craters they carved was difficult, said Arizona State University researcher Mark Robinson, who operates the orbiter's camera.

Even the mission's chief scientist, Maria Zuber, was surprised when she saw the impact sites, which looked like dots.

"I was expecting to see skid tracks," said Zuber of the Massachusetts Institute of Technology.

Ebb and Flow deliberately plunged into a lunar mountain in December after mapping the moon's gravity field in unprecedented detail. The location was chosen because it was far away from the Apollo landings and other historic sites.

Since the finale occurred in the dark, telescopes from Earth did not capture it. Even the reconnaissance orbiter had to wait until sunlight streamed to the northern lunar region.

Launched in 2011, the spacecraft spent nearly a year flying in formation, exclusively collecting gravitational data. Among the discoveries: The lunar crust is much thinner and more battered than scientists had imagined.

Initially flying at 35 miles above the lunar surface, the spacecraft dipped lower and lower in altitude during the $487 million mission.

Scientists are still poring through the last chunk of data beamed back just before their demise.

The Ebb and Flow crash sites were named in honor of mission team member, Sally Ride, the first American woman in space who died last year. Ride's educational company supplied the cameras on the mission that allowed students to take their own pictures of craters and other geological features.

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