Editing Apollo 12 (section)

===Outward journey===
[[File:A view of one-third of Earth, with Australia on the horizon, as photographed by the three-man crew of Apollo 12.jpg|thumb|right|View of Earth taken en route to the Moon]]

After systems checks in Earth orbit, performed with great care because of the lightning strikes, the trans-lunar injection burn, made with the S-IVB, took place at 02:47:22.80 into the mission, setting Apollo 12 on course for the Moon. An hour and twenty minutes later, the CSM separated from the S-IVB, after which Gordon performed the [[transposition, docking, and extraction]] maneuver to dock with the LM and separate the combined craft from the S-IVB, which was then sent on an attempt to reach solar orbit.{{sfn|Orloff & Harland 2006|p=333}}<ref name=tpe>{{cite web |url=https://history.nasa.gov/afj/ap12fj/03tde.html |title= Day 1, part 3: Transposition, Docking and Extraction |date=January 12, 2020|editor-last=Woods |editor-first=W. David |editor-last2=Waugh |editor-first2=Lennox J. |work=Apollo 12 Flight Journal |publisher=NASA |access-date=January 8, 2021 |df=mdy-all }}</ref> The stage fired its engines to leave the vicinity of the spacecraft, a change from Apollo 11, where the SM's Service Propulsion System (SPS) engine was used to distance it from the S-IVB.{{sfn|Harland 2011|p=141}}

As there were concerns the LM might have been damaged by the lightning strikes, Conrad and Bean entered it on the first day of flight to check its status, earlier than planned. They found no issues. At 30:52.44.36, the only necessary midcourse correction during the translunar coast was made, placing the craft on a hybrid, non-free-return trajectory. Previous crewed missions to lunar orbit had taken a [[free-return trajectory]], allowing an easy return to Earth if the craft's engines did not fire to enter lunar orbit. Apollo 12 was the first crewed spacecraft to take a hybrid free-return trajectory, that would require another burn to return to Earth, but one that could be executed by the LM's Descent Propulsion System (DPS) if the SPS failed. The use of a hybrid trajectory allowed more flexibility in mission planning. It for example allowed Apollo 12 to launch in daylight and reach the planned landing spot on schedule.{{sfn|Orloff & Harland 2006|pp=333–334}} Use of a hybrid trajectory meant that Apollo 12 took 8 hours longer to go from trans-lunar injection to lunar orbit.{{sfn|Harland 2011|p=154}}