Lagrange point
In celestial mechanics
Celestial mechanics is the branch of astronomy
Astronomy (from el, ἀστρονομία, literally meaning the science that studies the laws of the stars) is a natural science that studies astronomical ob ...
s of two-body systems in space.
Sun–Earth Lagrange points
L1
is the Lagrange point located approximately 1.5 million kilometers from Earth towards the Sun.Past probes
*International Cometary Explorer
The International Cometary Explorer (ICE) spacecraft
275px, The US Space Shuttle flew 135 times from 1981 to 2011, supporting Spacelab, ''Mir'', the Hubble Space Telescope, and the ISS. (''Columbia'' STS-1">maiden launch, which had a white e ...
, formerly the International Sun–Earth Explorer 3 (ISEE-3), diverted out of in 1983 for a comet rendezvous mission. Currently in heliocentric orbit
A heliocentric orbit (also called circumsolar orbit) is an orbit
In physics, an orbit is the gravitationally curved trajectory of an physical body, object, such as the trajectory of a planet around a star or a natural satellite around a plan ...
. The Sun–Earth L1 is also the point to which the Reboot ISEE-3 mission was attempting to return the craft as the first phase of a recovery mission (as of September 25, 2014 all efforts have failed and contact was lost).
*NASA's Genesis
Genesis may refer to:
Literature and comics
* Genesis (DC Comics), a 1997 DC Comics crossover
* Genesis (Marvel Comics), a Marvel Comics villain
* Genesis, a fictional character from the ''Preacher (comics), Preacher'' comic-book series
* ''Genes ...
probe collected solar wind samples at from December 3, 2001 to April 1, 2004, when it returned the sample capsule to Earth. It returned briefly in late 2004 before being pushed into heliocentric orbit in early 2005.
*LISA Pathfinder (LPF) was launched on 3 December 2015, and arrived at on 22 January 2016, where, among other experiments, it tested the technology needed by (e)LISA to detect gravitational waves. LISA Pathfinder used an instrument consisting of two small gold alloy cubes.
*The Chang'e 5 orbiter (during extended mission. After ferrying lunar samples back to Earth in 2020, the transport module was sent to where it is permanently stationed to conduct limited Earth-Sun observations.)
Present probes
* The Solar and Heliospheric Observatory (SOHO) in a halo orbit . WIND (spacecraft), WIND is also at . Currently slated for launch in late 2024, the Interstellar Mapping and Acceleration Probe will be placed near .
* The Advanced Composition Explorer (ACE) in a Lissajous orbit
* WIND (spacecraft), WIND (At since 2004)
* The Deep Space Climate Observatory (DSCOVR), designed to image the sunlit Earth in 10 wavelengths (EPIC) and monitor total reflected radiation (NISTAR). Launched on 11 February 2015, began orbiting L1 on 8 June 2015 to study the solar wind and its effects on Earth. DSCOVR is unofficially known as GORESAT, because it carries a camera always oriented to Earth and capturing full-frame photos of the planet similar to the Blue Marble. This concept was proposed by then-Vice President of the United States Al Gore in 1998 and was a centerpiece in his 2006 film ''An Inconvenient Truth''.
Planned probes
*Aditya-L1 *Interstellar Mapping and Acceleration Probe slated for launch in late 2024 *NEO Surveyor *SWFO-L1 *Lagrange_(spacecraft), Lagrange mission (ESA). One spacecraft in L1 and one in L5.L2
is the Lagrange point located approximately 1.5 million kilometers from Earth in the direction opposite the Sun. Spacecraft at the Sun–Earth L2 point are in a Lissajous orbit until decommissioned, when they are sent into a Heliocentric orbit, heliocentric graveyard orbit.Past probes
*2001 – 2010: NASA's WMAP, Wilkinson Microwave Anisotropy Probe (WMAP) observed the cosmic microwave background. It was moved to a heliocentric orbit to avoid posing a hazard to future missions.
*2003 – 2004: NASA's WIND (spacecraft), WIND. The spacecraft then went to Earth orbit, before heading to .
*2009 – 2013: The ESA Herschel Space Observatory exhausted its supply of liquid helium and was moved from the Lagrangian point in June 2013.
*2009 – 2013: At the end of its mission ESA's ''Planck (spacecraft), Planck'' spacecraft was put into a heliocentric orbit and Passivation (spacecraft), passivated to prevent it from endangering any future missions.
*2011 – 2012: CNSA's Chang'e 2. Chang'e 2 was then placed onto a heliocentric orbit that took it past the near-Earth asteroid 4179 Toutatis.
Present probes
* The ESA Gaia probe * The joint Russian-German high-energy astrophysics observatory Spektr-RG * The joint NASA, ESA and Canadian Space Agency, CSA James Webb Space Telescope (JWST) ''(arriving late January 2022)''Planned probes
*The ESA Euclid (spacecraft), Euclid mission, to better understand dark energy and dark matter by accurately measuring the acceleration of the universe. *The NASA Nancy Grace Roman Space Telescope (WFIRST) *The ESA PLATO (spacecraft), PLATO mission, which will find and characterize rocky exoplanets. *The JAXA LiteBIRD mission. *The ESA ARIEL mission, which will observe the atmospheres of exoplanets. *The joint ESA-JAXA Comet Interceptor *The ESA Advanced Telescope for High ENergy Astrophysics (ATHENA) *The NASA Advanced Technology Large-Aperture Space Telescope, which would replace the Hubble Space Telescope.Cancelled probes
*The ESA Eddington mission *The NASA Terrestrial Planet Finder mission (may be placed in an Earth-trailing orbit instead)L3
is the Sun–Earth Lagrange point located on the side of the Sun opposite Earth, slightly outside the Earth's orbit. * There are no known objects in this orbital location.L4
is the Sun–Earth Lagrange point located close to the Earth's orbit 60° ahead of Earth. * Asteroid is the first discovered Horseshoe orbit#Tadpole orbit, tadpole orbit companion to Earth, orbiting ; like Earth, its mean distance to the Sun is about one astronomical unit. *STEREO A (Solar TErrestrial RElations Observatory – Ahead) made its closest pass to in September 2009, on its orbit around the Sun, slightly faster than Earth.NASA - Join STEREO and Explore Gravitational "Parking Lots" That May Hold Secret of Moon's Origin/ref> * OSIRIS-REx passed near the L4 point and performed a survey for asteroids between 9 and 20 February 2017.
L5
is the Sun–Earth Lagrange point located close to the Earth's orbit 60° behind Earth. *Asteroid , in a Horseshoe orbit, horseshoe companion orbit with Earth, is currently proximal to but at a high inclination. *STEREO B (Solar TErrestrial RElations Observatory – Behind) made its closest pass to in October 2009, on its orbit around the Sun, slightly slower than Earth. *The Spitzer Space Telescope is in an Earth-trailing heliocentric orbit drifting away c. 0.1 Astronomical Unit, AU per year. In c. 2013–15 it has passed in its orbit. *''Hayabusa2'' passed near during the spring of 2017, and imaged the surrounding area to search for Earth trojans in 18 April 2018.Proposed
*Lagrange_(spacecraft), Lagrange mission (ESA). One spacecraft in L5 and one in L1.Earth–Moon Lagrange points
L2
* THEMIS#Extended mission, ARTEMIS * Chang'e 5-T1 * Chang'e 4#Components, Queqiao relay satelliteL4 and L5
*Kordylewski clouds *Future location of Tracking_and_Data_Relay_Satellite_System, TDRS-style communication satellites to support satellitePast probes
*Hiten was the first spacecraft to demonstrate a low energy transfer, low energy trajectory, passing by and to achieve lunar orbit at a very low fuel expense, compared to usual orbital techniques. Hiten did not find any conclusive increase in dust density at Lagrange points.Proposed objects
* Exploration Gateway Platform * In his 1976 book ''The High Frontier: Human Colonies in Space'' Dr. Gerard K. O'Neill, Gerard O'Neill proposed the establishment of gigantic Space habitat, ''Space Islands'' in . The inhabitants of the L5 Society should convert lunar material to huge solar power satellites. Many works of fiction, most notably the ''Gundam'' series, involve colonies at these locations.Sun–Venus Lagrange points
L4
*Sun–Mars Lagrange points
Asteroids in the and Sun–Mars Lagrangian points are sometimes called ''Mars trojans,'' with a lower-case t, as "Trojan asteroid" was originally defined as a term for Lagrangian asteroids of Jupiter. They may also be called ''Mars Lagrangian asteroids.''L4
*L5
*5261 Eureka * * *, , (not confirmed as true Lagrangian asteroids) Source: Minor Planet CenteSun–Jupiter Lagrange points
Asteroids in the and Sun–Jupiter Lagrangian points are known as ''Jupiter Trojan asteroids'' or simply ''Trojan asteroids''.L4
*List of Jupiter trojans (Greek camp), Trojan asteroids, Greek campL5
*List of Jupiter trojans (Trojan camp), Trojan asteroids, Trojan campSaturn–Tethys Lagrange points
L4
*Telesto (moon), TelestoL5
*Calypso (moon), CalypsoSaturn–Dione Lagrange points
L4
* Helene (moon), HeleneL5
* Polydeuces (moon), Polydeuces, follows a "tadpole" orbit around L5Sun–Uranus Lagrange points
L3
* 83982 Crantor, follows a horseshoe orbit around L3L4
*/ref> *
Sun–Neptune Lagrange points
Minor planets in the and Sun–Neptune Lagrangian points are called Neptune trojans, with a lower-case ''t'', as "Trojan asteroid" was originally defined as a term for Lagrangian asteroids of Jupiter. ''Data from:'' Minor Planet CenteL4
* 385571 Otrera * 385695 Clete * * * *L5
* * *Tables of missions
Color key:Future and proposed missions
See also
*Trojan points **Trojan asteroid **Trojan moon **Trojan planetFootnotes
{{DEFAULTSORT:List Of Objects At Lagrangian Points Trojans (astronomy) Space lists, objects Satellites orbiting Lagrange points,