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List of objects at Lagrangian points

Sun–Earth Lagrangian pointsEdit

L1Edit

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

Past probesEdit

  • 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.
  • 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

Present probesEdit

 
Animation of Deep Space Climate Observatory's trajectory from 11 February 2015 to 3 January 2017
  DSCOVR ·   Earth ·   Moon

Planned probesEdit

L2Edit

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

Past probesEdit

 
Animation of Wilkinson Microwave Anisotropy Probe's trajectory from 1 July 2001 to 7 April 2009
  WMAP ·   Earth
  • 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.
  • NASA's WIND from November 2003 to April 2004. The spacecraft then went to Earth orbit, before heading to L1.
  • The ESA Herschel Space Observatory exhausted its supply of liquid helium and was moved from the Lagrangian point in June 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.
  • 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.

Present probesEdit

Planned probesEdit

Cancelled probesEdit

L3Edit

L3 is the Sun–Earth Lagrangian 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.

L4Edit

L4 is the Sun–Earth Lagrangian 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 with a mean distance of about one astronomical unit.
  • 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.[2]
  • OSIRIS-REx passed near the L4 point and performed a survey for asteroids between 9 and 20 February 2017.

L5Edit

L5 is the Sun–Earth Lagrangian 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.[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 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 in 18 April 2018.[3]

ProposedEdit

Earth–Moon Lagrangian pointsEdit

L2Edit

L4 and L5Edit

Past probesEdit

  • 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.[5]

Proposed objectsEdit

Sun–Venus Lagrangian pointsEdit

Sun–Mars Lagrangian pointsEdit

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.

L4Edit

L5Edit

Source: Minor Planet Center [1]

Sun–Jupiter Lagrangian pointsEdit

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

L4Edit

L5Edit

Saturn–Tethys Lagrangian pointsEdit

Saturn–Dione Lagrangian pointsEdit

L4Edit

L5Edit

Sun–Uranus Lagrangian pointsEdit

L3Edit

L4Edit

Sun–Neptune Lagrangian pointsEdit

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.

L4Edit

L5Edit

Source: Minor Planet Center [2]

See alsoEdit

FootnotesEdit

  1. ^ "China's Moon orbiter Chang'e-2 travels 1.5 km into outer space". The Economic Times. 2011-08-30. Retrieved 2011-08-31.
  2. ^ a b NASA - Join STEREO and Explore Gravitational "Parking Lots" That May Hold Secret of Moon's Origin
  3. ^ "太陽−地球系のL5点付近の観測の結果について" (in Japanese). JAXA. 23 August 2017. Retrieved 2018-06-22.
  4. ^ Slíz-Balogh, Judith; Barta, András; Horváth, Gábor (11 November 2018). "Celestial mechanics and polarization optics of the Kordylewski dust cloud in the Earth–Moon Lagrange point L5 – I. Three-dimensional celestial mechanical modelling of dust cloud formation". Monthly Notices of the Royal Astronomical Society. 480 (4): 5550–5559. doi:10.1093/mnras/sty2049.
  5. ^ "Hiten", NSSDC.GSFC.NASA.gov.
  6. ^ 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