1. Home
2. Apollo program
3. Earth Orbit Rendezvous

Earth Orbit Rendezvous

Gemini 7 as seen from Gemini 6 during their rendezvous in Earth orbit in 1965. (NASA)

Earth orbit rendezvous (EOR) is a type of space rendezvous, a method that has been proposed for space missions to the Moon. NASA considered an EOR mission profile for the Apollo program, but chose instead to use Lunar Orbit Rendezvous (LOR). NASA had plans to use both EOR and LOR for Project Constellation, which is to include human spaceflight missions to the Moon beginning around 2020.

Gemini and Agena target vehicle

The Agena target vehicle was used for testing Earth orbit rendezvous in the NASA Gemini Program. Gemini 6 and Gemini 7 rendezvoused in orbit in 1965, but without Agena. Next, Gemini 8 successfully docked March 16, 1966 with the Agena. The Agena-Gemini rendezvous also achieved many other tasks in later Gemini launches.

Apollo

The EOR proposal for Apollo consisted of using a series of small rockets half the size of a Saturn V to put different components of a spacecraft to go to the Moon in orbit around the Earth, then assemble them in orbit. Experiments of Project Gemini involving docking with the Agena target vehicle were designed partly to test the feasibility of this program. In the end, NASA employed the Lunar Orbit Rendezvous for the Apollo Program, using the Saturn V to boost both the Apollo Command and Lunar Modules into low Earth orbit, and then firing again to send both spacecraft out to the Moon.

Constellation

This mode had been revived for Project Constellation as the Earth Departure Stage (EDS) and Altair (LSAM), which would be launched into low Earth orbit on the Ares V rocket. The EDS and Altair would be met by the separately launched Orion (CEV). Once joined in low Earth orbit, the three would then travel out to the Moon and the Orion/Altair combination would fly a lunar orbit rendezvous flight pattern.