Contents

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[edit]

Sun–Earth L₁[edit]

L₁ is the Lagrange point located approximately 1.5 million kilometers from Earth towards the Sun.

Past probes[edit]

• International Cometary Explorer, formerly the International Sun–Earth Explorer 3 (ISEE-3), diverted out of L₁ 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).^[1]
• NASA's Genesis probe collected solar wind samples at L₁ 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 L₁ 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^[2] (during extended mission. After ferrying lunar samples back to Earth in 2020, the transport module was sent to L₁ where it is permanently stationed to conduct limited Earth-Sun observations.)

Present probes[edit]

• The Solar and Heliospheric Observatory (SOHO) in a halo orbit around L1
  • Mission: Investigation of the outer layer of the Sun, making observations of solar wind and associated phenomena in the vicinity of L1, probing the interior structure of the Sun.
  • Launched: 2 December 1995
  • Arrival: Operational orbit in May 1996
  • Institution: ESA
• The Advanced Composition Explorer (ACE) in a Lissajous orbit
• WIND (AtL₁ 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.^[3] 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^[4] and was a centerpiece in his 2006 film An Inconvenient Truth.^[5]
• Aditya-L1 was successfully launched on 2 September 2023 and entered the halo orbit around the lagrange point on 6 January 2024.^[6] It's a Solar observation mission by ISRO. It will study solar atmosphere, solar magnetic storms, and their impact on the environment around the Earth.^[7]

Planned probes[edit]

• Interstellar Mapping and Acceleration Probe slated for launch in late 2024
• NEO Surveyor
• SWFO-L1
• Vigil (ESA). One spacecraft in L1 and one in L5.

Sun–Earth L₂[edit]

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.^{[citation needed]}

Past probes[edit]

• 2001 – 2010: NASA's Wilkinson Microwave Anisotropy Probe (WMAP)^[8] 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 L₁.^[9]
• 2009 – 2013:^[10] 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.^[11][12] Chang'e 2 was then placed onto a heliocentric orbit that took it past the near-Earth asteroid 4179 Toutatis.

Present probes[edit]

• 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)
• The ESA Euclid mission

Planned probes[edit]

• 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 Advanced Telescope for High ENergy Astrophysics (ATHENA)
• 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[edit]

• The ESA Eddington mission
• The NASA Terrestrial Planet Finder mission (may be placed in an Earth-trailing orbit instead)

Sun–Earth L₃[edit]

L₃ is the Sun–Earth Lagrange point located on the side of the Sun opposite Earth, slightly outside the Earth's orbit. Direct communication with spacecraft in this position is blocked by the sun.

• There are no known objects in this orbital location. ^{[citation needed]}

Sun–Earth L₄[edit]

L₄ is the Sun–Earth Lagrange point located close to the Earth's orbit 60° ahead of Earth.

• Asteroid 2010 TK7 is the first discovered tadpole orbit companion to Earth, orbiting L₄; like Earth, its mean distance to the Sun is about one astronomical unit.
• Asteroid 2020 XL5 is the second Earth trojan, confirmed in November 2021, oscillating around L₄ in a tadpole orbit and expected to remain there for at least 4000 years, until destabilized by Venus.^[13]
• STEREO A (Solar TErrestrial RElations Observatory – Ahead) made its closest pass to L₄ in September 2009, on its orbit around the Sun, slightly faster than Earth.^[14]
• OSIRIS-REx passed near the L4 point and performed a survey for asteroids between 9 and 20 February 2017.

Sun–Earth L₅[edit]

L₅ is the Sun–Earth Lagrange point located close to the Earth's orbit 60° behind Earth.

• Asteroid (419624) 2010 SO16, in a horseshoe companion orbit with Earth, is currently proximal to L₅ but at a high inclination.
• STEREO B (Solar TErrestrial RElations Observatory – Behind) made its closest pass to L₅ in October 2009, on its orbit around the Sun, slightly slower than Earth.^[14]
• 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 L₅ in its orbit.
• Hayabusa2 passed near L₅ during the spring of 2017, and imaged the surrounding area to search for Earth trojans on 18 April 2018.^[15]

Proposed[edit]

• Vigil (ESA). One spacecraft in L5.

Earth–Moon Lagrange points[edit]

Earth–Moon L2[edit]

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

Earth–Moon L4 and L5[edit]

• Kordylewski clouds^[16]
• Future location of TDRS-style communication satellites to support L₂ satellite and further regions on the Moon.^[17][18]

Past probes[edit]

• Hiten was the first spacecraft to demonstrate a low energy trajectory, passing by L₄ and L₅ 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.^[19]

Proposed objects[edit]

• Exploration Gateway Platform
• In his 1976 book The High Frontier: Human Colonies in Space Dr. Gerard O'Neill proposed the establishment of gigantic Space IslandsinL₅. 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[edit]

L4[edit]

• 2013 ND15

Sun–Mars Lagrange points[edit]

Asteroids in the L₄ and L₅ 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[edit]

• (121514) 1999 UJ7

L5[edit]

• 5261 Eureka
• (101429) 1998 VF31
• (311999) 2007 NS2
• (385250) 2001 DH47, 2001 FG24, 2001 FR127 (not confirmed as true Lagrangian asteroids)

Source: Minor Planet Center [1]

Sun–Ceres Lagrange points[edit]

• 1372 Haremari
• (76146) 2000 EU16
• (185105) 2006 SV23

Sun–Jupiter Lagrange points[edit]

Asteroids in the L₄ and L₅ Sun–Jupiter Lagrangian points are known as Jupiter Trojan asteroids or simply Trojan asteroids.

L4[edit]

• Trojan asteroids, Greek camp

L5[edit]

• Trojan asteroids, Trojan camp

Planned[edit]

• Lucy (spacecraft)

Saturn–Tethys Lagrange points[edit]

L4[edit]

• Telesto

L5[edit]

• Calypso

Saturn–Dione Lagrange points[edit]

L4[edit]

• Helene

L5[edit]

• Polydeuces, follows a "tadpole" orbit around L₅

Sun–Uranus Lagrange points[edit]

L3[edit]

• 83982 Crantor, follows a horseshoe orbit around L₃

L4[edit]

• 2011 QF99^[20]
• 2014 YX49

Sun–Neptune Lagrange points[edit]

Minor planets in the L₄ and L₅ 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 Center [2]

L4[edit]

• 385571 Otrera
• 385695 Clete
• 2001 QR322
• 2005 TN53
• 2006 RJ103
• 2007 VL305

L5[edit]

• 2008 LC18
• 2004 KV18
• 2011 HM102

Tables of missions[edit]

Color key:
  Unflown or planned mission   Mission en route or in progress (including mission extensions)   Mission at Lagrangian point completed successfully (or partially successfully)

Future and proposed missions[edit]

See also[edit]

• Trojan (celestial body)
• Co-orbital configuration

Footnotes[edit]

Stars

Spaceflight

Outer space

Solar System