List of objects at Lagrangian points

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

Contents 1 Sun-Earth Lagrangian points 1.1 L1 1.1.1 Past probes 1.1.2 Present probes 1.1.3 Planned probes 1.1.4 Cancelled probes 1.2 L2 1.2.1 Past probes 1.2.2 Present probes 1.2.3 Planned probes 1.2.4 Cancelled probes 1.3 L3 1.4 L4 1.5 L5 2 Earth-Moon Lagrangian points 2.1 L2 2.2 L4 and L5 2.3 Proposed objects 3 Sun-Mars Lagrangian points 3.1 L4 3.2 L5 4 Sun-Jupiter Lagrangian points 4.1 L4 4.2 L5 5 Saturn-Tethys Lagrangian points 5.1 L4 5.2 L5 6 Saturn-Dione Lagrangian points 6.1 L4 6.2 L5 7 Sun-Neptune Lagrangian points 7.1 L4 8 See also 9 Footnotes

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)
• The ESA Planck Surveyor

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 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.

• STEREO A (Solar TErrestrial RElations Observatory – Ahead) The twin STEREO spacecraft passed through L₄ and L₅ in autumn 2009.^[1]
• Dust clouds ^[2]

L₅

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

• STEREO B (Solar TErrestrial RElations Observatory – Behind)
• 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.
• Dust Clouds

Earth-Moon Lagrangian points

L₂

• None

L₄ and L₅

• possible Kordylewski clouds
• STEREO A and B will search for Earth Lagrangian asteroids as they pass through the L₄ and L₅ regions, respectively, in 2010. They will have another opportunity as they loop back around through the opposite Lagrangian points several years later.
• 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