Transposition, docking, and extraction (often abbreviated totransposition and docking) was a maneuver performed duringApollolunar landing missions from 1969 to 1972, to withdraw theApollo Lunar Module (LM) from itsadapter housing which secured it to theSaturn Vlaunch vehicle upper stage and protected it from theaerodynamic stresses of launch. The maneuver involved the command module pilot separating theApollo Command and Service Module (CSM) from the adapter, turning the CSM around, anddocking its nose to the Lunar Module, then pulling the combined spacecraft away from the upper stage. It was performed shortly after thetrans-lunar injection maneuver that placed theApollo spacecraft on a three-day trajectory to theMoon. The docking created a continuous, pressurized tunnel which permitted the astronauts to transfer internally between the CSM and the LM.
The same maneuver was performed on the 1975Apollo–Soyuz Test Project (ASTP) mission to extract a special docking module used to connect the Apollo Command Module with theSoyuz spacecraft.
Transposition and docking was performed by theCommand Module Pilot (CMP) (although, as a backup, the Commander andLunar Module Pilot (or ASTP Docking Module Pilot) were also trained to perform the maneuver), and involved the following steps:
The astronauts were in no hurry to complete this maneuver, which nominally took about an hour.[1] It would take longer if problems were encountered; for instance,Stuart Roosa had trouble getting the capture latches to engage for docking onApollo 14, and the procedure took two hours and eighteen minutes.[2]
Transposition and docking was performed on all Apollo missions which carried both the CSM and the LM, fromApollo 9 onward. Transposition and a mock LM-docking approach was first simulated on theEarth-orbitingApollo 7 flight (which carried a docking target in the SLA, but no LM). The "Block I" SLA used on the earlySaturn IB launch vehicles had panels that opened at a 45° angle but did not separate from the S‑IVB. One of the panels did not open the full angle, preventing the crew from approaching the S‑IVB for fear they might strike this panel. This was corrected with the "Block II" SLA design used on all crewedSaturn V Apollo flights (starting withApollo 8), which detached the panels and pushed them away from the S‑IVB with springs.
The last mission to use the maneuver was theApollo–Soyuz Test Project mission, in which the Apollo CSM docked to a specially designed adapter module which carried docking equipment compatible with theSoyuz 19 spacecraft.
