List of objects at Lagrangian points

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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.

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

SunEarth Lagrangian points[edit]

L1[edit]

L1 is the Lagrangian point located approximately 1.5 million km towards the Sun away from the Earth.

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, 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 the sample capsule to Earth. It returned briefly in late 2004 before being pushed into heliocentric orbit in early 2005.

Present probes[edit]

Planned probes[edit]

L2[edit]

L2 is the Lagrangian point located approximately 1.5 million km away from the Earth in the direction opposite the Sun.

Past probes[edit]

  • NASA's Wilkinson Microwave Anisotropy Probe (WMAP) observed the cosmic microwave background from 2001 until 2010. It was moved to a heliocentric orbit to avoid posing a hazard to future missions.
  • CNSA's Chang'e 2[1] from August 2011 to April 2012. Chang'e 2 was then placed onto a heliocentric orbit that took it past the near-Earth asteroid 4179 Toutatis.
  • The ESA Herschel Space Observatory exhausted its supply of liquid helium and was moved away from the Lagrangian point in June 2013.

Present probes[edit]

Planned probes[edit]

Cancelled probes[edit]

L3[edit]

L3 is the Sun–Earth 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[edit]

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

L5[edit]

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

  • Asteroid 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) makes its closest pass to L5 in October 2009, on its orbit around the Sun, slightly slower than the Earth.[2]
  • The Spitzer Space Telescope is in an Earth-trailing heliocentric orbit drifting away c. 0.1 AU per year. In c. 2013–15 it will pass L5 in its orbit.
  • Dust clouds[3][not in citation given][citation needed]

Earth–Moon Lagrangian points[edit]

L2[edit]

L4 and L5[edit]

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

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.[4]

Proposed objects[edit]

Sun–Mars Lagrangian 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]

L5[edit]

Source: Minor Planet Center [1]

Sun–Jupiter Lagrangian points[edit]

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

L4[edit]

L5[edit]

SaturnTethys Lagrangian points[edit]

L4[edit]

L5[edit]

SaturnDione Lagrangian points[edit]

L4[edit]

L5[edit]

Sun–Uranus Lagrangian points[edit]

L4[edit]

Sun–Neptune Lagrangian 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.

L4[edit]

L5[edit]

Source: Minor Planet Center [2]

See also[edit]

Footnotes[edit]