Trans-Earth injection is a term describing the propulsion maneuver

Maneuver

Maneuver, manoeuvre may be a synonym for strategy or tactic. It is the manipulation of a situation in order to gain some advantage.- Military or naval movement :* Military exercise...

 used to set 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....

 on a trajectory

Trajectory

A trajectory is the path that a moving object follows through space as a function of time. The object might be a projectile or a satellite, for example. It thus includes the meaning of orbit—the path of a planet, an asteroid or a comet as it travels around a central mass...

 which will intersect 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...

.

The maneuver is performed by a rocket

Rocket

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...

 engine. The spacecraft is usually in a parking orbit

Parking orbit

A parking orbit is a temporary orbit used during the launch of a satellite or other space probe. A launch vehicle boosts into the parking orbit, then coasts for a while, then fires again to enter the final desired trajectory...

 around the Moon

Moon

The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

 at the time of TEI, in which case the burn is timed so that its mid-point is opposite the Earth's location upon arrival. Unmanned space probes have also performed this maneuver from the Moon starting with Luna 16

Luna 16

-External links:*...

's direct ascent traverse from the lunar surface in 1970. In 2004, from outside the Earth-Moon system, the Stardust probe

Stardust (spacecraft)

Stardust is a 300-kilogram robotic space probe launched by NASA on February 7, 1999 to study the asteroid 5535 Annefrank and collect samples from the coma of comet Wild 2. The primary mission was completed January 15, 2006, when the sample return capsule returned to Earth...

 comet dust return mission performed TEI after visiting Comet Wild 2

81P/Wild

Comet 81P/Wild, also known as Wild 2 , is a comet named after Swiss astronomer Paul Wild, who discovered it in 1978 using a 40-cm Schmidt telescope at Zimmerwald....

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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

Apollo 8

Apollo 8, the second manned mission in the American Apollo space program, was the first human spaceflight to leave Earth orbit; the first to be captured by and escape from the gravitational field of another celestial body; and the first crewed voyage to return to Earth from another celestial...

mission on December 25, 1968.