Apollo 15 15 separated from the booster, the S-IVB maneuvered away, and would impact the Moon about an hour after the crewed spacecraft entered lunar orbit, though due to an error the impact was away from the intended target. The booster's impact was detected by the seismometers left on the Moon by Apollo 12 and Apollo 14, providing useful scientific data. There was a malfunctioning light on the craft's service propulsion system (SPS); after considerable troubleshooting, the astronauts did a test burn of the system that also served as a midcourse correction. This occurred about 028:40:00 into the mission. Fearing that the
Apollo 4 Apollo 4 Apollo 4, (also known as AS-501), was the first unmanned test flight of the Saturn V launch vehicle, which was used by the U.S. Apollo program to send the first astronauts to the Moon. The space vehicle was assembled in the Vertical Assembly Building, and was the first to be launched from Launch Complex 39 at the John F. Kennedy Space Center on Merritt Island, Florida, facilities built specially for the Saturn V. Apollo 4 was an "all-up" test, meaning all rocket stages and spacecraft were fully functional on the initial flight, a first for NASA. It was