Earth orbit rendezvous

Earth orbit rendezvous (EOR) is a method for conducting round trip human flights to the Moon, involving the use of space rendezvous to assemble, and possibly fuel, components of a translunar vehicle in low Earth orbit.

[1] It was considered as an alternative to direct ascent but ultimately rejected in favor of lunar orbit rendezvous (LOR) for NASA's Apollo program of the 1960s and 1970s,[2] mainly because LOR does not require a spacecraft big enough to both make the return trip from Earth orbit to splash down in the ocean and a soft landing on the lunar surface.

[6] The Agena target vehicle (ATV) was used for testing Earth orbit rendezvous in the NASA Gemini Program.

Experiments of Project Gemini involving docking with the Agena target vehicle were designed partly to test the feasibility of this program.

[citation needed] In the end, NASA employed the Lunar Orbit Rendezvous for the Apollo Program: a Saturn V would simultaneously lift both the Apollo Command and Lunar Modules into low Earth orbit, and then the Saturn V third stage would fire again (Trans-lunar injection) to send both spacecraft to the Moon.