page_title: Return of Apollo 15 to Earth
section_title: Rendezvous and docking
hierarchical_section_title: Return of Apollo 15 to Earth / Rendezvous and docking
context_page_description: After the Apollo 15 LM Falcon lifted from the lunar surface on August 2, 1971, it rendezvoused and docked with the CSM Endeavour. After transferring across the lunar samples and other equipment, Falcon was jettisoned. It would fire its rocket engine to cause it to impact the lunar surface.
  Apollo 15 spent one more day in lunar orbit, continuing Worden's observations. After releasing a subsatellite, they ignited their service propulsion system to put them on a trajectory back to Earth. The next day, Worden performed an EVA to retrieve the film cassettes from the scientific instrument module bay cameras.
  The twelfth day in space was uneventful, with Mission Control holding a press conference where the astronauts were asked questions submitted by the news media. On their 13th and final day they prepared for reentry. During descent one of their three parachutes failed, and they splashed down successfully with only two.
context_section_description: Falcon lifted off from the lunar surface at 171 hours, 37 minutes and 16 seconds GET. During ascent from the Moon, Worden played "The Air Force Song". Although he thought it was only being played for Houston, unbeknownst to him, a switch had been flicked in Mission Control that relayed his voice transmissions to the LM. It is understood that Scott was not very happy with this, as it was impossible to make out any communications from Mission Control while the song played.
  The LM was placed into a 42 by 9 nm (77.8 by 16.7 km) orbit. Apollo 15 would be the first direct rendezvous, where the two craft would rendezvous within one orbit. The LM orbit was not perfectly in the same plane as the CSM's, so another burn of the LM's ascent engine was required.
  During the following near side pass, the spacecraft continued to close, with Falcon, in its lower orbit, catching Endeavour. Once about 120 feet (40 m) apart the spacecraft started to station-keep — keeping the distance between them constant. As on all Apollo flights, the crew extensively photographed and filmed this process. Endeavour closed in to hard dock and the mission of Falcon had come to an end.
  After opening the hatches, the crew began the task of transferring the rock samples that had been collected on the surface. Scott and Irwin also vacuumed their spacesuits to try to rid them of as much dust as possible. Also transferred were film magazines, food, used urine and fecal bags (they were included for medical investigators). One Oxygen Purge System (OPS) was also transferred. On the lunar surface the OPS would be used as an emergency oxygen supply, or by the crew of the LM in the event that they were unable to achieve hard docking with the CSM and had to undertake an EVA to transfer across from the LM. Worden would use it during his EVA later in the mission.
  Following the completion of the transfer, the crew resealed the hatches between the two craft and prepared to jettison the LM. This was different from the undocking that took place before landing. In this case it would be an explosive jettison as much of the docking probe structure was now unneeded and will stay in the LM. There was some difficulty in getting the tunnel between the craft to depressurize. This suggested that there was an improperly sealed hatch, delaying the separation by one orbit. After checking the hatches the crew could not find a cause for the improper seal, but the tunnel now vented successfully.  In his 2001 memoir, Flight Director Christopher Kraft wrote that some of these difficulties may have been the result of crew fatigue. Because of the longer lunar stay time, by this point Scott and Irwin had gone an arduous 22 hours without sleep, and both men had experienced some heart irregularities on the lunar surface after their EVAs. Kraft wrote that coordination between ground controllers and the crew broke down several times at this point in the mission, and he recalled this as one of the most stressful experiences during his career in mission control.
  A change in crew procedure had come after the deaths of three crewmembers of Soyuz 11 less than a month before the launch of Apollo 15. On Soyuz 11 the crew had been killed after a repressurization valve opened during the separation of the orbital and service modules from the reentry module of the Soyuz spacecraft. Mission planners for Apollo 15 decided that the crew should now wear their pressure suits during the separation of the LM from the CSM, something that had not previously occurred. The suits caused some problems for 15 as during an integrity test before the tunnel venting they were unable to achieve suit integrity in Scott's suit.
  After finally jettisoning the LM, the CSM performed a small RCS burn to further separate from the LM. Falcon was directed to burn its ascent stage engine, so that it would impact the lunar surface. The delay has meant it would not impact in the planned site, instead impacting at 26°12' N, 0°6' E, about 56 miles (90 km) from the landing site.
  The crew should have started their sleep period, but due to the del
caption: Apollo 15's LM Falcon as seen by the CSM Endeavour, during rendezvous. The object in the foreground is the EVA floodlight.
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