List of objects at Lagrange points

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

A diagram showing the five Lagrangian points in a two-body system

Sun-Earth Lagrangian points

L₁

L₁ is the Lagrangian point located approximately 1,500,000 km towards the Sun away from the Earth.

Past probes

• 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 solar orbit, it may be captured in 2014 when it next approaches Earth.
• NASA's Genesis probe collected solar wind samples at L1 from December 3, 2001 to April 1, 2004, when it returned to Earth.

Present probes

• GGS WIND
• The Solar and Heliospheric Observatory (SOHO)
• The Advanced Composition Explorer (ACE)

Planned probes

• LISA Pathfinder
• Kuafu

Cancelled probes

• The Triana satellite, designed to monitor global warming.

L₂

L₂ is the Lagrangian point located approximately 1,500,000 km away from the Earth in the direction opposite the Sun.

Past probes

• GEOTAIL

Present probes

• Wilkinson Microwave Anisotropy Probe (WMAP)

Planned probes

• The joint NASA, ESA and CSA James Webb Space Telescope (JWST), formerly known as the Next Generation Space Telescope (NGST)
• The ESA Herschel Space Observatory
• The ESA Planck Surveyor
• The ESA Gaia probe
• The NASA Terrestrial Planet Finder mission (may be placed in an Earth-trailing orbit instead)
• The ESA Darwin mission
• The NASA Advanced Technology Large-Aperture Space Telescope, that will replace both the Hubble Space Telescope and JWST.

Cancelled probes

• The ESA Eddington mission

L₃

L₃ is the Lagrangian point located on the side of the Sun opposite the Earth, slightly outside the Earth's orbit.

• There are no known objects in this orbital location.

L₄

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

• Dust clouds ^[1]

L₅

L₅ is the Lagrangian point located close to the Earth's orbit 60° behind the Earth.

• Dust clouds
• Spitzer is in an earth-trailing heliocentric orbit drifting away circa 0.1 AU per year. In circa 2013-15 it will pass L₅ in its orbit.

Earth-Moon Lagrangian points

L₂

• None

L₄ and L₅

• possible Kordylewski clouds
• future location of TDRS-style communication satellites to support L₂ satellite

Proposed objects

In his book "The High Frontier" Dr. Gerard O'Neill proposed the establishment of gigantic Space Islands in L₅. The inhabitants of the L5 Society should convert Lunar material to huge solar power satellites.

Sun-Mars Lagrangian points

Asteroids in the L₄ and L₅ Mars-Sun Lagrangian points are sometimes called Mars Trojan asteroids, but "Trojan asteroid", as originally defined, is a term for asteroids in the L₄ and L₅ Jupiter-Sun Lagrangian points.

L₄

• 1999 UJ7

L₅

• 5261 Eureka
• 1998 VF31, 2001 DH47, 2001 FG24, 2001 FR127 (not confirmed as true Lagrangian asteroids)

Sun-Jupiter Lagrangian points

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

L₄

• Trojan asteroids, Greek camp

L₅

• Trojan asteroids, Trojan camp

Saturn-Tethys Lagrangian points

L₄

• Telesto

L₅

• Calypso

Saturn-Dione Lagrangian points

L₄

• Helene

L₅

• Polydeuces

Sun-Neptune Lagrangian points

Asteroids in the L₄ and L₅ Neptune-Sun Lagrangian points are sometimes called Neptune Trojan asteroids, but "Trojan asteroid", as originally defined, is a term for asteroids in the L₄ and L₅ Jupiter-Sun Lagrangian points.

L₄

• 2001 QR322
• 2004 UP10
• 2005 TN53
• 2005 TO74
• 2006 RJ103
• 2007 VL305

Source: Minor Planet Center [2]

See also

• Trojan points
• Trojan asteroid
• Trojan moon
• Trojan planet

References

1. ^ John Baez' Lagrange Points page

Footnotes