Apollo 9 to land on the Moon; when the crews for Apollo 8 and 9 were swapped, their backup crews were also swapped. Since the rule of thumb was for backup crews to fly as prime crew three missions later, this put Neil Armstrong's crew (Borman's backup) in position for the first landing mission Apollo 11 instead of Pete Conrad's crew, who made the second landing on Apollo 12. Apollo 9 was the first space test of the complete Apollo spacecraft, including the third critical piece of Apollo hardware besides the command and service module and the Saturn V launch vehicle—the lunar
Apollo Applications Program the crew. The "Apollo Manned Survey Mission" proposed an Earth-observation science module also based on the LM ascent stage, and would also have been launched using a S-IVB vehicle into a high-inclination orbit. It was also proposed that a surplus Saturn V would launch a manned lunar survey mission to establish suitable sites for later manned landings. The wet workshop space station concept provided for a low-budget Earth orbiting station. The original plan, as proposed by Wernher von Braun, used the S-II stage as the primary structure of the station, with the area normally filled by the S-IVB stage replaced