Earth orbit rendezvous
Encyclopedia
Space rendezvous
A space rendezvous is an orbital maneuver during which two spacecraft, one of which is often a space station, arrive at the same orbit and approach to a very close distance . Rendezvous requires a precise match of the orbital velocities of the two spacecraft, allowing them to remain at a constant...
and a spaceflight methodology most notable for enabling round trip human missions to the moon. While considered and ultimately rejected by NASA for the Apollo moon landing missions in favor of its cousin Lunar orbit rendezvous
Lunar orbit rendezvous
Lunar orbit rendezvous is a key concept for human landing on the Moon and returning to Earth.In a LOR mission a main spacecraft and a smaller lunar module travel together into lunar orbit. The lunar module then independently descends to the lunar surface. After completion of the mission there, a...
(LOR), Earth orbit rendezvous was an integral component of Project Constellation's
Project Constellation
Constellation Program is a human spaceflight program within NASA, the space agency of the United States. The stated goals of the program were to gain significant experience in operating away from Earth's environment, develop technologies needed for opening the space frontier, and conduct...
planned human spaceflight missions to the Moon beginning around 2020 before that program’s cancellation in October 2010.
Gemini and Agena target vehicle
The Agena target vehicleAgena Target Vehicle
The Agena Target Vehicle was an unmanned spacecraft used by NASA during its Gemini program to develop and practice orbital space rendezvous and docking techniques and to perform large orbital changes, in preparation for the Apollo program lunar missions.-Operations:Each ATV consisted of an Agena-D...
was used for testing Earth orbit rendezvous in the NASA Gemini Program. Gemini 6 and Gemini 7
Gemini 7
Gemini 7 was a 1965 manned spaceflight in NASA's Gemini program. It was the 4th manned Gemini flight, the 12th manned American flight and the 20th spaceflight of all time . The crew of Frank F. Borman, II and James A...
rendezvoused in orbit in 1965, but without Agena. Next, Gemini 8
Gemini 8
-Backup crew:-Mission parameters:* Mass: * Perigee: * Apogee: * Inclination: 28.91°* Period: 88.83 min-Objectives:Gemini VIII had two major objectives, of which it achieved one...
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 rocketRocket
A rocket is a missile, spacecraft, aircraft or other vehicle which obtains thrust from a rocket engine. In all rockets, the exhaust is formed entirely from propellants carried within the rocket before use. Rocket engines work by action and reaction...
s half the size of a Saturn V
Saturn V
The Saturn V was an American human-rated expendable rocket used by NASA's Apollo and Skylab programs from 1967 until 1973. A multistage liquid-fueled launch vehicle, NASA launched 13 Saturn Vs from the Kennedy Space Center, Florida with no loss of crew or payload...
to put different components of a spacecraft
Spacecraft
A spacecraft or spaceship is a craft or machine designed for spaceflight. Spacecraft are used for a variety of purposes, including communications, earth observation, meteorology, navigation, planetary exploration and transportation of humans and cargo....
to go to the Moon in orbit
Orbit
In physics, an orbit is the gravitationally curved path of an object around a point in space, for example the orbit of a planet around the center of a star system, such as the Solar System...
around the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
, then assemble them in orbit. Experiments of Project Gemini
Project Gemini
Project Gemini was the second human spaceflight program of NASA, the civilian space agency of the United States government. Project Gemini was conducted between projects Mercury and Apollo, with ten manned flights occurring in 1965 and 1966....
involving docking with the Agena target vehicle
Agena Target Vehicle
The Agena Target Vehicle was an unmanned spacecraft used by NASA during its Gemini program to develop and practice orbital space rendezvous and docking techniques and to perform large orbital changes, in preparation for the Apollo program lunar missions.-Operations:Each ATV consisted of an Agena-D...
were designed partly to test the feasibility of this program. In the end, NASA employed the Lunar Orbit Rendezvous
Lunar orbit rendezvous
Lunar orbit rendezvous is a key concept for human landing on the Moon and returning to Earth.In a LOR mission a main spacecraft and a smaller lunar module travel together into lunar orbit. The lunar module then independently descends to the lunar surface. After completion of the mission there, a...
for the Apollo Program
Project Apollo
The Apollo program was the spaceflight effort carried out by the United States' National Aeronautics and Space Administration , that landed the first humans on Earth's Moon. Conceived during the Presidency of Dwight D. Eisenhower, Apollo began in earnest after President John F...
, using the Saturn V to boost both the Apollo Command and Lunar Modules
Apollo Lunar Module
The Apollo Lunar Module was the lander portion of the Apollo spacecraft built for the US Apollo program by Grumman to carry a crew of two from lunar orbit to the surface and back...
into low Earth orbit, and then firing again to send both spacecraft out to the Moon.
Constellation
This mode had been revived for Project ConstellationProject Constellation
Constellation Program is a human spaceflight program within NASA, the space agency of the United States. The stated goals of the program were to gain significant experience in operating away from Earth's environment, develop technologies needed for opening the space frontier, and conduct...
as the Earth Departure Stage
Earth Departure Stage
The Ares V Earth Departure Stage was a rocket stage which NASA planned to design at its Marshall Space Flight Center in Huntsville, Alabama as part of Project Constellation...
(EDS) and Altair (LSAM), which would be launched into low Earth orbit on the Ares V
Ares V
The Ares V was the planned cargo launch component of the Constellation program, which was to have replaced the Space Shuttle after its retirement in 2011. Ares V was also planned to carry supplies for a human presence on Mars...
rocket. The EDS and Altair would be met by the separately launched Orion
Orion (spacecraft)
Orion is a spacecraft designed by Lockheed Martin for NASA, the space agency of the United States. Orion development began in 2005 as part of the Constellation program, where Orion would fulfill the function of a Crew Exploration Vehicle....
(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
Lunar orbit rendezvous
Lunar orbit rendezvous is a key concept for human landing on the Moon and returning to Earth.In a LOR mission a main spacecraft and a smaller lunar module travel together into lunar orbit. The lunar module then independently descends to the lunar surface. After completion of the mission there, a...
flight pattern.