25-Dec-1968 :- First Trans-Earth injection ( TEI ) performed by Apollo 8 mission.

A Trans-Earth injection (TEI) is a propulsion maneuver used to set a spacecraft on a trajectory which will intersect the Earth.

On the Apollo missions, it was performed by the restartable Service Propulsion System (SPS) engine on the Service Module. An Apollo TEI burn lasted approximately 203.7 seconds, providing a posigrade velocity increase of 1,076 m/s (3,531 ft/s). It was first performed by the Apollo 8 mission on December 25, 1968.