List Of Objects At Lagrange Points

This is a list of known objects which occupy, have occupied, or are planned to occupy any of the five Lagrange points of two-body systems in space.

Sun–Earth Lagrange points

Sun–Earth L₁

is the Lagrange point located approximately 1.5 million kilometers from Earth towards the Sun.

Past probes

*International Cometary Explorer, formerly the International Sun–Earth Explorer 3 (ISEE-3), diverted out of in 1983 for a comet rendezvous mission. Currently in heliocentric orbit. 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 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
* The Advanced Composition Explorer (ACE) in a Lissajous orbit
* 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 (ATHENA)
* Lagrange mission (ESA). One spacecraft in L1 and one in L5.

Sun–Earth 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 graveyard orbit.

Past probes

*2001 – 2010: NASA's 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. 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 was put into a heliocentric orbit and 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 CSA James Webb Space Telescope (JWST)

Planned probes

*The ESA 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 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 NASA Large Ultraviolet Optical Infrared Surveyor (LUVOIR) 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)

Sun–Earth 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.

Sun–Earth L₄

is the Sun–Earth Lagrange point located close to the Earth's orbit 60° ahead of Earth.

* Asteroid is the first discovered tadpole orbit companion to Earth, orbiting ; like Earth, its mean distance to the Sun is about one astronomical unit.
* Asteroid is the second Earth trojan, confirmed in November 2021, oscillating around in a tadpole orbit and expected to remain there for at least 4000 years, until destabilized by Venus.
* 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
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* OSIRIS-REx passed near the L4 point and performed a survey for asteroids between 9 and 20 February 2017.

Sun–Earth L₅

is the Sun–Earth Lagrange point located close to the Earth's orbit 60° behind Earth.

*Asteroid , in a 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 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 on 18 April 2018.

Proposed

* Lagrange mission (ESA). One spacecraft in L5 and one in L1.

Earth–Moon Lagrange points

Earth–Moon L2

* THEMIS
* Chang'e 5-T1
* Queqiao relay satellite
* EQUULEUS nanosat.

Earth–Moon L4 and L5

*Kordylewski clouds
*Future location of TDRS-style communication satellites to support satellite

Past probes

* Hiten was the first spacecraft to demonstrate a 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 O'Neill proposed the establishment of gigantic ''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 Cente

Sun–Jupiter Lagrange points

Asteroids in the and Sun–Jupiter Lagrangian points are known as ''Jupiter Trojan asteroids'' or simply ''Trojan asteroids''.

L4

* Trojan asteroids, Greek camp

L5

* Trojan asteroids, Trojan camp

Planned

* Lucy (spacecraft)

Saturn–Tethys Lagrange points

L4

* Telesto

L5

* Calypso

Saturn–Dione Lagrange points

L4

* Helene

L5

* Polydeuces, follows a "tadpole" orbit around L₅

Sun–Uranus Lagrange points

L3

* 83982 Crantor, follows a horseshoe orbit around L₃

L4

* The first known Uranian Trojan and the frequency of temporary giant-planet co-orbitals: Mike Alexandersen, Brett Gladman, Sarah Greenstreet, J.J. Kavelaars, Jean-Marc Petit
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*

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 Cente

L4

* 385571 Otrera
* 385695 Clete
*
*
*
*

L5

*
*
*

Tables of missions

Color key:

Future and proposed missions

See also

*Trojan (celestial body)
*Co-orbital configuration

Footnotes

{{DEFAULTSORT:Objects At Lagrangian Points
Trojans (astronomy)
Space lists