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Probes in a Lissajous Orbit

There are a few probes which are kind of in an Earth orbit, but not really. This type of orbit is called a Lissajous orbit. It is a path around the L1 or L2 Lagrangian points of a two-body system. Lissajous orbits are utilized by certain spacecraft that are required to be in a stable position relative to the Earth and Sun while making long-term observations. In a Lissajous orbit the spacecraft follows a natural (but complex) motion that requires the minimum amount of energy for station-keeping, unlike a halo orbit, in which the craft follows a simple circular or elliptical path.

Lagrange points are locations in space where gravitational forces and the orbital motion of a body balance each other. They were discovered by French mathematician Louis Lagrange in 1772 in his gravitational studies of the ‘Three body problem’: how a third, small body would orbit around two orbiting large ones.

There are five Lagrangian points in the Sun-Earth system and such points also exist in the Earth-Moon system. L1 and L2 in the Sun-Earth system are stable and most used.

L1 is located about 1.5 million km from Earth, between the sun and Earth, along a line from the sun to Earth. L2 is located about 1.5 million km from Earth along the same line, but on the other side of Earth.


Page last modified: 04 December 2015 12:40:19.