The empty rocket stage struck the lunar surface at approximately 7:35 a.m. British Summer Time, or 6:35 a.m. GMT, traveling at roughly 5,400 miles per hour, or about 8,700 kilometers per hour, according to tracking data cited by researchers. A Predictable Piece of Space DebrisThe rocket stage originated from a Falcon 9 launch that lifted off from Florida in January of last year, carrying two lunar landers into space. The mission's primary objective, successfully sending both landers beyond Earth's orbit and onto a trajectory toward the Moon, was accomplished at the time. Astronomers tracking the derelict rocket stage eventually determined that those small perturbations had placed it on a collision course with the Moon, with its velocity increasing day by day as it approached. Part of a Long History of Lunar ImpactsWednesday's collision is far from the first time human-made hardware has struck the Moon.