Orbits
Astrodynamics
In
orbital mechanics
Orbital mechanics or astrodynamics is the application of ballistics and celestial mechanics to rockets, satellites, and other spacecraft. The motion of these objects is usually calculated from Newton's laws of motion and the law of universal ...
, a transfer orbit is an intermediate
elliptical orbit
In astrodynamics or celestial mechanics, an elliptical orbit or eccentric orbit is an orbit with an orbital eccentricity, eccentricity of less than 1; this includes the special case of a circular orbit, with eccentricity equal to 0. Some or ...
that is used to move a
spacecraft
A spacecraft is a vehicle that is designed spaceflight, to fly and operate in outer space. Spacecraft are used for a variety of purposes, including Telecommunications, communications, Earth observation satellite, Earth observation, Weather s ...
in an
orbital maneuver
In spaceflight, an orbital maneuver (otherwise known as a burn) is the use of propulsion systems to change the orbit of a spacecraft.
For spacecraft far from Earth, an orbital maneuver is called a ''deep-space maneuver (DSM)''.
When a spacec ...
from one
circular, or largely circular,
orbit
In celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an ...
to another.
There are several types of transfer orbits, which vary in their
energy efficiency and speed of transfer. These include:
*
Hohmann transfer orbit
In astronautics, the Hohmann transfer orbit () is an orbital maneuver used to transfer a spacecraft between two orbits of different altitudes around a central body. For example, a Hohmann transfer could be used to raise a satellite's orbit fro ...
, an elliptical orbit used to transfer a spacecraft between two circular orbits of different altitudes in the same plane
*
Bi-elliptic transfer, a slower method of transfer, but one that may be more efficient than a Hohmann transfer orbit
*
Geostationary transfer orbit
In space mission design, a geostationary transfer orbit (GTO) or geosynchronous transfer orbit is a highly elliptical type of geocentric orbit, usually with a perigee as low as low Earth orbit (LEO) and an apogee as high as geostationary orbit ...
or
geosynchronous
A geosynchronous orbit (sometimes abbreviated GSO) is an Earth-centered orbit with an orbital period that matches Earth's rotation on its axis, 23 hours, 56 minutes, and 4 seconds (one sidereal day). The synchronization of rotation and orbital ...
transfer orbit is usually also a Hohmann transfer orbit
* ''Lunar transfer orbit'' is an orbit that touches
Low Earth orbit
A low Earth orbit (LEO) is an geocentric orbit, orbit around Earth with a orbital period, period of 128 minutes or less (making at least 11.25 orbits per day) and an orbital eccentricity, eccentricity less than 0.25. Most of the artificial object ...
and a
lunar orbit
In astronomy and spaceflight, a lunar orbit (also known as a selenocentric orbit) is an orbit by an object around Earth's Moon. In general these orbits are not circular. When farthest from the Moon (at apoapsis) a spacecraft is said to be at apo ...
.
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