NASA’s Lunar Atmosphere and Dust Environment Explorer spacecraft slammed into the moon early Friday morning, as planned, but a few days earlier than NASA officials expected.

At about 12:30 a.m. Eastern time, radio signals from the spacecraft abruptly cut off just as it passed over to the far side of the moon. Mission managers believe that is the moment when it ran into a crater rim — they suspect they even know which crater rim — but that has not been confirmed yet.

The crash brought to a successful end a six-month, $280 million study of the tenuous envelope of gases and dust surrounding the moon. With impact at 3,600 miles per hour, the vending-machine-size spacecraft, called Ladee (pronounced LAD-ee), broke up into pieces that heated up to hundreds of degrees and partly vaporized. “It’s just a question of whether Ladee made a localized craterlet on a hillside or scattered debris across a flat area,” Richard C. Elphic, the project scientist, said in a NASA news release.

Mission managers had expected that Ladee would stay in orbit until Monday.

On April 11, the spacecraft fired its engine one last time to swoop in closer to sample the gas and dust at the very lowest parts of the lunar atmosphere. By design, the elliptical orbit was oriented to ensure that Ladee would crash on the far side of the moon, away from the historic Apollo landing sites.