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 (spacecraft) the point where it was no longer needed, and the SLA remained attached to the launch vehicle's upper stage. Two unmanned CSM's, one unmanned LM and one manned CSM were carried into space by Saturn IB launch vehicles for low Earth orbit Apollo missions. Larger Saturn Vs launched two unmanned CSM's on high Earth orbit test flights, the CSM on one manned lunar mission, the complete spacecraft on one manned low Earth orbit mission and eight manned lunar missions. After conclusion of the Apollo program, four CSM's were launched on Saturn IBs for three Skylab Earth orbital missions and the