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.

Sun-Earth

WIND (USA) 1 November 1994. Built to study radio and plasma that occur in the solar wind..
Advanced Composition Explorer (ACE) (USA) 25 August 1997. ACE studies matter comprised of energetic particles, such as those found in the solar wind.
Wilkinson Microwave Anisotropy Probe (WMAP) (USA) 30 June 2001.
Herschel Space Observatory (ESA) 14 May 2009. Launched along with the Planck spacecraft. This is an infrared telescope looking for the coldest and dustiest objects in space.
Planck (ESA) 14 May 2009. Launched along with the Herschel Space Observatory. Built to study cosmic wave background.
LISA Pathfinder (ESA) 3 December 2015. Bound for L1, the Laser Interferometer Space Antenna is an experimental spacecraft designed to test technologies for the detection and measurement of gravitational waves.
Deep Space Climate Observatory (DSCOVR) (USA) 11 February 2015. National Oceanic and Atmospheric Administration (NOAA) space weather, space climate, and Earth observation satellite. It reached L1 on 8 June 2015.
James Webb Space Telescope (USA/ESA/CSA) 25 December 2021. Bound for L2, the JWST will be able to capture images of some of the first galaxies ever formed. It will also be able to observe objects in our solar system from Mars outward, look inside dust clouds to see where new stars and planets are forming and examine the atmospheres of planets orbiting other stars. L2 arrival was in January 2022. (Description credit: NASA)
Euclid (ESA) 1 July 2023. Launched by a Falcon 9, this telescope will measure photometric and spectroscopic redshifts for a very large number of galaxies. It was placed it on a transfer trajectory to Sun-Earth L2.
Aditya-L1 (India) 2 September 2023. Launched from Satish Dhawan Space Centre, is headed to the L1 Sun-Earth Lagrangian point where it will track solar activity.

Earth-Moon

Queqiao (China) 20 May 2018. This is an communications and radio astronomy relay satellite for the Chang'e 4 lunasr probe. It entered into a orbit around the Earth-Moon L2 point on 14 June 2018.

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: 02 September 2023 08:43:59.