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 15 postal covers incident about ; they entered the spacecraft in Scott's pocket. Apollo 15 blasted off for the Moon at 9:34 am on July 26, 1971, with three astronauts and about 641 covers aboard. At some point while the mission was en route to the Moon, the 400 covers were moved into the lunar lander "Falcon"; in his testimony, Scott agreed this violated the rules. He stated he did not recall how the transfer took place, and that he was only certain that the envelopes went to the lunar surface because they were in the bag of items taken out of the "Falcon"