Temporary satellite

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A temporary satellite is an object which has been captured by the gravitational field of a planet and thus has become the planet's natural satellite, but, unlike irregular moons of the larger outer planets of the Solar System, will eventually either leave its orbit around the planet or collide with the planet. The only observed examples are 2006 RH120 , a temporary satellite of Earth for twelve months from July 2006 to July 2007, 2020 CD3 [1] [2] and 2022 NX1. Some defunct space probes or rockets have also been observed on temporary satellite orbits. [3]

Contents

In astrophysics, a temporary satellite is any body that enters the Hill sphere of a planet at a sufficiently low velocity such that it becomes gravitationally bound to the planet for some period of time. [4]

Capture of asteroids

The dynamics of the capture of asteroids by Earth was explored in simulations conducted on a supercomputer, [5] with results published in 2012. [6] Of 10 million virtual near-Earth asteroids, 18,000 have been temporarily captured. [6] Earth has at least one temporary satellite 1 m (3.3 ft) across at any given time, but they are too faint to detect by current surveys. [5]

According to the simulations, temporary satellites are typically caught and released when they pass one of two gravitational equilibrium points of the Sun and the planet along the line connecting the two, the L1 and L2 Lagrangian points. [5] The captured asteroids typically have orbits very similar to the planet's (co-orbital configuration) and are captured most often when the planet is closest to the Sun (in the case of the Earth, in January) or furthest from the Sun (Earth: in July). [5]

In strict sense, only bodies that complete a full orbit around a planet are considered temporary satellites, also called temporarily captured orbiters (TCO). However, asteroids not in a tight co-orbital configuration with a planet can be temporarily captured for less than a full orbit; such objects have been named temporarily-captured fly-bys (TCF). [7] In a 2017 follow-up to the 2012 simulation study which also considered an improved model of near-Earth asteroid populations, 40% of captured objects were TCF. The combined number of TCO/TCF was found to be smaller than in the previous study, the maximum size of objects which can be expected to be orbiting Earth at any given moment was 0.8 m (2.6 ft). [7] In another 2017 study based on simulations with one million virtual co-orbital asteroids, 0.36% have been temporarily captured. [8]

Examples

As of February 2020, two objects have been observed at the time when they were temporary satellites: 2006 RH120 [1] [9] [10] and 2020 CD3. [11] According to orbital calculations, on its solar orbit, 2006 RH120 passes Earth at low speed every 20 to 21 years, [10] at which point it can become a temporary satellite again.

As of March 2018, there is one confirmed example of a temporarily captured asteroid that didn't complete a full orbit, 1991 VG . [8] This asteroid was observed for a month after its discovery in November 1991, then again in April 1992, after which it wasn't seen until May 2017. [12] After the recovery, orbital calculations confirmed that 1991 VG was a temporary satellite of Earth in February 1992. [8] Another temporary capture episode was experienced by 2022 NX1 that may return as a mini-moon in December 2051. [13] [14] Another temporary capture episode is predicted to occur from September 29, 2024 to November 25, 2024, when 2024 PT5 is captured by Earth. [15]

Known and suspected companions of Earth
Name Eccentricity Diameter
(m)		DiscovererDate of DiscoveryTypeCurrent Type
Moon 0.0553474800 ?Prehistory Natural satellite Natural satellite
1913 Great Meteor Procession  ? ? ?1913-02-09Possible Temporary satellite Destroyed
3753 Cruithne 0.5155000 Duncan Waldron 1986-10-10 Quasi-satellite Horseshoe orbit
1991 VG 0.0535–12 Spacewatch 1991-11-06 Temporary satellite Apollo asteroid
(85770) 1998 UP1 0.345210–470 Lincoln Lab's ETS 1998-10-18 Horseshoe orbit Horseshoe orbit
54509 YORP 0.230124 Lincoln Lab's ETS 2000-08-03 Horseshoe orbit Horseshoe orbit
2001 GO2 0.16835–85 Lincoln Lab's ETS 2001-04-13Possible Horseshoe orbit Possible Horseshoe orbit
2002 AA29 0.01320–100 LINEAR 2002-01-09 Quasi-satellite Horseshoe orbit
2003 YN107 0.01410–30 LINEAR 2003-12-20 Quasi-satellite Horseshoe orbit
(164207) 2004 GU9 0.136160–360 LINEAR 2004-04-13 Quasi-satellite Quasi-satellite
(277810) 2006 FV35 0.377140–320 Spacewatch 2006-03-29 Quasi-satellite Quasi-satellite
2006 JY26 0.0836–13 Catalina Sky Survey 2006-05-06 Horseshoe orbit Horseshoe orbit
2006 RH120 0.0242–3 Catalina Sky Survey 2006-09-13 Temporary satellite Apollo asteroid
(419624) 2010 SO16 0.075357 WISE 2010-09-17 Horseshoe orbit Horseshoe orbit
(706765) 2010 TK7 0.191150–500 WISE 2010-10-01 Earth trojan Earth trojan
2013 BS45 0.08320–40 Spacewatch 2010-01-20 Horseshoe orbit Horseshoe orbit
2013 LX28 0.452130–300 Pan-STARRS 2013-06-12 Quasi-satellite temporary Quasi-satellite temporary
2014 OL339 0.46170–160 EURONEAR 2014-07-29 Quasi-satellite temporary Quasi-satellite temporary
2015 SO2 0.10850–110 Črni Vrh Observatory 2015-09-21 Quasi-satellite Horseshoe orbit temporary
2015 XX169 0.1849–22 Mount Lemmon Survey 2015-12-09 Horseshoe orbit temporary Horseshoe orbit temporary
2015 YA 0.2799–22 Catalina Sky Survey 2015-12-16 Horseshoe orbit temporary Horseshoe orbit temporary
2015 YQ1 0.4047–16 Mount Lemmon Survey 2015-12-19 Horseshoe orbit temporary Horseshoe orbit temporary
469219 Kamoʻoalewa 0.10440-100 Pan-STARRS 2016-04-27 Quasi-satellite stable Quasi-satellite stable
DN16082203  ? ? ?2016-08-22Possible Temporary satellite Destroyed
2020 CD3 0.0171–6 Mount Lemmon Survey 2020-02-15 Temporary satellite Apollo asteroid
2020 PN1 0.12710–50 ATLAS-HKO 2020-08-12 Horseshoe orbit temporary Horseshoe orbit temporary
2020 PP1 0.07410–20 Pan-STARRS 2020-08-12 Quasi-satellite stable Quasi-satellite stable
(614689) 2020 XL5 0.3871100-1260 Pan-STARRS 2020-12-12 Earth trojan Earth trojan
2022 NX1 0.0255-15Moonbase South Observatory2020-07-02Temporary satellite Apollo asteroid
2023 FW13 0.17710-20 Pan-STARRS 2023-03-28 Quasi-satellite Quasi-satellite
2024 PT5 0.0217–13 ATLAS South Africa, Sutherland 2024-08-07 Temporary satellite Temporary satellite

Artificial objects on temporary satellite orbits

The Earth can also temporarily capture defunct space probes or rockets travelling on solar orbits, in which case astronomers cannot always immediately determine whether the object is artificial or natural. The possibility of an artificial origin has been considered for both 2006 RH120 [1] and 1991 VG . [8]

The artificial origin has been confirmed in other cases. In September 2002, astronomers found an object designated J002E3. The object was on a temporary satellite orbit around Earth, leaving for a solar orbit in June 2003. Calculations showed that it was also on a solar orbit before 2002, but was close to Earth in 1971. J002E3 was identified as the third stage of the Saturn V rocket that carried Apollo 12 to the Moon. [16] [3] In 2006, an object designated 6Q0B44E was discovered on a temporary satellite orbit, later its artificial nature was confirmed, but its identity is unknown. [3] Another confirmed artificial temporary satellite with unidentified origin is 2013 QW1. [3]

See also

Related Research Articles

<span class="mw-page-title-main">Near-Earth object</span> Small Solar System body with an orbit that can bring it close to Earth

A near-Earth object (NEO) is any small Solar System body orbiting the Sun whose closest approach to the Sun (perihelion) is less than 1.3 times the Earth–Sun distance. This definition applies to the object's orbit around the Sun, rather than its current position, thus an object with such an orbit is considered an NEO even at times when it is far from making a close approach of Earth. If an NEO's orbit crosses the Earth's orbit, and the object is larger than 140 meters (460 ft) across, it is considered a potentially hazardous object (PHO). Most known PHOs and NEOs are asteroids, but about 0.35% are comets.

<span class="mw-page-title-main">Solar System</span> The Sun and objects orbiting it

The Solar System is the gravitationally bound system of the Sun and the objects that orbit it. It was formed about 4.6 billion years ago when a dense region of a molecular cloud collapsed, forming the Sun and a protoplanetary disc. The Sun is a typical star that maintains a balanced equilibrium by the fusion of hydrogen into helium at its core, releasing this energy from its outer photosphere. Astronomers classify it as a G-type main-sequence star.

<span class="mw-page-title-main">Natural satellite</span> Astronomical body that orbits a planet

A natural satellite is, in the most common usage, an astronomical body that orbits a planet, dwarf planet, or small Solar System body. Natural satellites are colloquially referred to as moons, a derivation from the Moon of Earth.

The Arjuna asteroids are a dynamical group of asteroids in the Solar System. Arjunas are near-Earth objects (NEOs) whose orbits are very Earth-like in character, having low inclination, orbital periods close to one year, and low eccentricity. The group is named after Arjuna, a central hero in Hindu historic script Mahabharata. The definition is somewhat more relevant and overlaps the definition of the four well-established Apollo, Amor, Aten and Atira groups. They constitute a dynamically cold group of small NEOs that experience repeated trappings in the 1:1 mean-motion resonance with the Earth.

<span class="mw-page-title-main">Quasi-satellite</span> Type of satellite in sync with another orbit

A quasi-satellite is an object in a specific type of co-orbital configuration with a planet where the object stays close to that planet over many orbital periods.

<span class="mw-page-title-main">Horseshoe orbit</span> Type of co-orbital motion of a small orbiting body relative to a larger orbiting body

In celestial mechanics, a horseshoe orbit is a type of co-orbital motion of a small orbiting body relative to a larger orbiting body. The osculating (instantaneous) orbital period of the smaller body remains very near that of the larger body, and if its orbit is a little more eccentric than that of the larger body, during every period it appears to trace an ellipse around a point on the larger object's orbit. However, the loop is not closed but drifts forward or backward so that the point it circles will appear to move smoothly along the larger body's orbit over a long period of time. When the object approaches the larger body closely at either end of its trajectory, its apparent direction changes. Over an entire cycle the center traces the outline of a horseshoe, with the larger body between the 'horns'.

<span class="mw-page-title-main">Irregular moon</span> Captured satellite following an irregular orbit

In astronomy, an irregular moon, irregular satellite, or irregular natural satellite is a natural satellite following a distant, inclined, and often highly elliptical and retrograde orbit. They have been captured by their parent planet, unlike regular satellites, which formed in orbit around them. Irregular moons have a stable orbit, unlike temporary satellites which often have similarly irregular orbits but will eventually depart. The term does not refer to shape; Triton, for example, is a round moon but is considered irregular due to its orbit and origins.

<span class="mw-page-title-main">6Q0B44E</span> Object in high Earth orbit

6Q0B44E, sometimes abbreviated to B44E, is a small object that was discovered orbiting Earth outside the orbit of the Moon in August 2006. It was observed until March 2007, at which point it was lost. It is likely, though unproven, that the same object was re-discovered as XL8D89E, which was observed between 2015 and 2018.

<span class="mw-page-title-main">Trojan (celestial body)</span> Objects sharing the orbit of a larger one

In astronomy, a trojan is a small celestial body (mostly asteroids) that shares the orbit of a larger body, remaining in a stable orbit approximately 60° ahead of or behind the main body near one of its Lagrangian points L4 and L5. Trojans can share the orbits of planets or of large moons.

<span class="mw-page-title-main">Claimed moons of Earth</span> Claims that Earth may have other natural satellites

Claims of the existence of other moons of Earth—that is, of one or more natural satellites with relatively stable orbits of Earth, other than the Moon—have existed for some time. Several candidates have been proposed, but none have been confirmed. Since the 19th century, scientists have made genuine searches for more moons, but the possibility has also been the subject of a number of dubious non-scientific speculations as well as a number of likely hoaxes.

2006 RH120 is a tiny near-Earth asteroid and fast rotator with a diameter of approximately 2–3 meters that ordinarily orbits the Sun but makes close approaches to the Earth–Moon system around every twenty years, when it can temporarily enter Earth orbit through temporary satellite capture (TSC). Most recently, it was in Earth orbit from July 2006 to July 2007, during which time it was never more than 0.0116 AU (1.74 million km) from Earth. As a consequence of its temporary orbit around the Earth, it is currently the second smallest asteroid in the Solar System with a well-known orbit, after 2021 GM1. Until given a minor planet designation on 18 February 2008, the object was known as 6R10DB9, an internal identification number assigned by the Catalina Sky Survey.

<span class="mw-page-title-main">Mars trojan</span> Celestial bodies that share the orbit of Mars

The Mars trojans are a group of trojan objects that share the orbit of the planet Mars around the Sun. They can be found around the two Lagrangian points 60° ahead of and behind Mars. The origin of the Mars trojans is not well understood. One theory suggests that they were primordial objects left over from the formation of Mars that were captured in its Lagrangian points as the Solar System was forming. However, spectral studies of the Mars trojans indicate this may not be the case. Another explanation involves asteroids chaotically wandering into the Mars Lagrangian points later in the Solar System's formation. This is also questionable considering the short dynamical lifetimes of these objects. The spectra of Eureka and two other Mars trojans indicates an olivine-rich composition. Since olivine-rich objects are rare in the asteroid belt it has been suggested that some of the Mars trojans are captured debris from a large orbit-altering impact on Mars when it encountered a planetary embryo.

<span class="mw-page-title-main">Retrograde and prograde motion</span> Relative directions of orbit or rotation

Retrograde motion in astronomy is, in general, orbital or rotational motion of an object in the direction opposite the rotation of its primary, that is, the central object. It may also describe other motions such as precession or nutation of an object's rotational axis. Prograde or direct motion is more normal motion in the same direction as the primary rotates. However, "retrograde" and "prograde" can also refer to an object other than the primary if so described. The direction of rotation is determined by an inertial frame of reference, such as distant fixed stars.

<span class="mw-page-title-main">1991 VG</span> Near-Earth object

1991 VG is a very small near-Earth object of the Apollo group, approximately 5–12 meters in diameter. It was first observed by American astronomer James Scotti on 6 November 1991, using the Spacewatch telescope on Kitt Peak National Observatory near Tucson, Arizona, in the United States. On 6 December 1991 it passed about 369635 km from the Moon. The asteroid then went unobserved from April 1992 until it was recovered by Paranal Observatory in May 2017. It was removed from the Sentry Risk Table on 1 June 2017.

2014 OL339 (also written 2014 OL339) is an Aten asteroid that is a temporary quasi-satellite of Earth, the fourth known Earth quasi-satellite.

<span class="mw-page-title-main">WT1190F</span> Small temporary satellite of Earth that impacted in 2015

WT1190F was a small temporary satellite of Earth that impacted Earth on 13 November 2015 at 06:18:21.7 UTC. It is thought to have been space debris from the trans-lunar injection stage of the 1998 Lunar Prospector mission. It was first discovered on 18 February 2013 by the Catalina Sky Survey. It was then lost, and reacquired on 29 November 2013. It was again discovered on 3 October 2015 by astronomer Rose Garcia with the Catalina Sky Survey 60-inch telescope, and the object was soon identified to be the same as the two objects previously sighted by the team, who have been sharing their data through the International Astronomical Union's Minor Planet Center (MPC). An early orbit calculation showed that it was orbiting Earth in an extremely elliptical orbit, taking it from within the geosynchronous satellite ring to nearly twice the distance of the Moon. It was also probably the same object as 9U01FF6, another object on a similar orbit discovered on 26 October 2009.

<span class="nowrap">2020 CD<sub>3</sub></span> Temporary satellite of Earth

2020 CD3 (also CD3 for short) is a tiny near-Earth asteroid (or minimoon) that ordinarily orbits the Sun but makes close approaches to the Earth–Moon system, in which it can temporarily enter Earth orbit through temporary satellite capture (TSC). It was discovered at the Mount Lemmon Observatory by astronomers Theodore Pruyne and Kacper Wierzchoś on 15 February 2020, as part of the Mount Lemmon Survey or Catalina Sky Survey. The asteroid's discovery was announced by the Minor Planet Center on 25 February 2020, after subsequent observations confirmed that it was orbiting Earth.

2022 NX1 is a near-Earth object roughly 10 meters (33 ft) in diameter discovered by Grzegorz Duszanowicz and Jordi Camarasa. The object orbits the Sun but makes slow close approaches to the Earth–Moon system. Between 11 June 2022 and 3 July 2022 (a period of 22 days) it passed within Earth's Hill sphere (roughly 0.01 AU (1.5 million km; 0.93 million mi)) at a low relative velocity and became temporarily captured by Earth's gravity, with a geocentric orbital eccentricity of less than 1 and negative geocentric orbital energy. Due to its Earth-like orbit, the object might be of artificial origin or lunar ejecta. However, visible spectroscopy obtained with the Gran Telescopio Canarias shows that it is an asteroid. The closest approach to Earth in 2022 was 26 June 2022 at roughly 812,200 km (504,700 mi) when it had a relative velocity of 0.96 km/s (2,100 mph). It was last near Earth around 16 January 1981 when it passed about 600,000 km (370,000 mi) from Earth. It will return as a temporary satellite in December 2051.

2023 FY3 is a near-Earth object roughly 5 meters (16 ft) in diameter discovered by K. W. Wierzchos observing with the 0.68-m Schmidt + 10K CCD of the Catalina Sky Survey.

2024 PT5 is a near-Earth object roughly 11 meters (36 ft) in diameter discovered by ATLAS South Africa, Sutherland on 7 August 2024, the day before approaching Earth at 568,500 km (353,200 mi).

References

  1. 1 2 3 "2006 RH120 ( = 6R10DB9) (A second moon for the Earth?)". Great Shefford Observatory. September 14, 2017. Archived from the original on 2015-02-06. Retrieved 2017-11-13.
  2. ↑ "MPEC 2020-D104 : 2020 CD3: Temporarily Captured Object". Minor Planet Electronic Circular. Minor Planet Center. 25 February 2020. Retrieved 25 February 2020.
  3. 1 2 3 4 Azriel, Merryl (September 25, 2013). "Rocket or Rock? NEO Confusion Abounds". Space Safety Magazine. Archived from the original on 2017-11-15. Retrieved 2017-11-14.
  4. ↑ Lissauer, Jack J.; de Pater, Imke (2019). Fundamental Planetary Sciences : physics, chemistry, and habitability. New York, NY, USA: Cambridge University Press. p. 34. ISBN   9781108411981. Comets or other bodies that enter the Hill sphere of a planet at very low velocity can remain gravitationally bound to the planet for some time as temporary satellites.
  5. 1 2 3 4 Camille M. Carlisle (December 30, 2011). "Pseudo-moons Orbit Earth". Sky & Telescope.
  6. 1 2 "Earth Usually Has More than One Moon, Study Suggests". Space.com. April 4, 2012.
  7. 1 2 Fedorets, Grigori; Granvik, Mikael; Jedicke, Robert (March 15, 2017). "Orbit and size distributions for asteroids temporarily captured by the Earth-Moon system". Icarus. 285: 83–94. Bibcode:2017Icar..285...83F. doi:10.1016/j.icarus.2016.12.022.
  8. 1 2 3 4 de la Fuente Marcos, C.; de la Fuente Marcos, R. (January 21, 2018). "Dynamical evolution of near-Earth asteroid 1991 VG". Monthly Notices of the Royal Astronomical Society. 473 (3): 2939–2948. arXiv: 1709.09533 . Bibcode:2018MNRAS.473.2939D. doi: 10.1093/mnras/stx2545 .
  9. ↑ Roger W. Sinnott (April 17, 2007). "Earth's "Other Moon"". Sky & Telescope. Archived from the original on 2012-04-02. Retrieved 2017-11-13.
  10. 1 2 "2006 RH120. Close-Approach Data". JPL Small-Body Database Browser. NASA/JPL. Archived from the original on February 11, 2017. Retrieved 2017-11-13.
  11. ↑ "MPEC 2020-D104 : 2020 CD3: Temporarily Captured Object". Minor Planet Electronic Circular. Minor Planet Center. 25 February 2020. Retrieved 25 February 2020.
  12. ↑ "1991 VG Orbit". Minor Planet Center . Retrieved 2018-03-12.
  13. ↑ de la Fuente Marcos, Carlos; de la Fuente Marcos, Raúl (12 August 2022). "How to Become a Mini-moon: Some Hints from 2022 NX1". Research Notes of the AAS . 6 (8): 160. Bibcode:2022RNAAS...6..160D. doi: 10.3847/2515-5172/ac8809 . S2CID   251538919.
  14. ↑ de la Fuente Marcos, Raúl; de León, Julia; de la Fuente Marcos, Carlos; Licandro, Javier; Serra-Ricart, Miquel; Cabrera-Lavers, Antonio (2 February 2023). "Mini-moons from horseshoes: A physical characterization of 2022 NX1 with OSIRIS at the 10.4 m Gran Telescopio Canarias". Astronomy & Astrophysics Letters. 670 (1): L10 (8 pages). arXiv: 2301.10797 . Bibcode:2023A&A...670L..10D. doi: 10.1051/0004-6361/202245514 .
  15. ↑ de la Fuente Marcos, Carlos; de la Fuente Marcos, Raúl (10 September 2024). "A Two-month Mini-moon: 2024 PT5 Captured by Earth from September to November". Research Notes of the AAS . 8 (9): 224. Bibcode:2024RNAAS...8..224D. doi: 10.3847/2515-5172/ad781f .
  16. ↑ Chesley, Steve; Chodas, Paul (October 9, 2002). "J002E3: An Update". News. NASA. Archived from the original on 2003-05-03. Retrieved 2017-11-14.
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