Quasi-satellite

Venus has one known quasi-satellite, (524522) 2002 VE68. This asteroid is also a Mercury- and Earth-crosser; it seems to have been a "companion" to Venus for approximately the last 7000 years only, and is destined to be ejected from this orbital arrangement about 500 years from now.[2]

As of 2016, Earth had five known quasi-satellites:

• (164207) 2004 GU9[3]
• (277810) 2006 FV35[4]
• 2013 LX28[5]
• 2014 OL339[6]
• 469219 Kamo‘oalewa[7][8]

On the longer term, asteroids can transfer between quasi-satellite orbits and horseshoe orbits, which circulate around Lagrangian points L4 and L5. By 2016, orbital calculations showed that all five of Earth's then known quasi-satellites repeatedly transfer between horseshoe and quasi-satellite orbits.[8] 3753 Cruithne,[9] 2002 AA29,[1] 2003 YN107 and 2015 SO2[5] are minor planets in horseshoe orbits that might evolve into a quasi-satellite orbit. The time spent in the quasi-satellite phase differs from asteroid to asteroid. Quasi-satellite 2016 HO₃ is predicted to be stable in this orbital state for several hundred years, in contrast to 2003 YN₁₀₇ which was a quasi-satellite from 1996 to 2006 but then departed Earth's vicinity on a horseshoe orbit.[8][10]

469219 Kamoʻoalewa (2016 HO₃) is thought to be one the most stable quasi-satellites found yet of Earth. It stays between 38 and 100 lunar distances from the Earth.[10]

(309239) 2007 RW10 is a temporary quasi-satellite of Neptune.[11] The object has been a quasi-satellite of Neptune for about 12,500 years and it will remain in that dynamical state for another 12,500 years.[11]

Based on simulations, it is believed that Uranus and Neptune could potentially hold quasi-satellites for the age of the Solar System (about 4.5 billion years),[12] but a quasi-satellite's orbit would remain stable for only 10 million years near Jupiter and 100,000 years near Saturn. Jupiter and Saturn are known to have quasi-satellites. 2015 OL₁₀₆, a co-orbital to Jupiter, intermittently becomes a quasi satellite of the planet, and will next become one between 2380 and 2480.

In early 1989, the Soviet Phobos 2 spacecraft was injected into a quasi-satellite orbit around the Martian moon Phobos, with a mean orbital radius of about 100 kilometres (62 mi) from Phobos.[13] According to computations, it could have then stayed trapped in the vicinity of Phobos for many months. The spacecraft was lost due to a malfunction of the on-board control system.

Some objects are known to be accidental quasi-satellites, which means that they are not forced into the configuration by the gravitational influence of the body of which they are quasi-satellites.[14] The minor planets Ceres, Vesta, and Pluto are known to have accidental quasi-satellites.[14] In the case of Pluto, the known accidental quasi-satellite, 15810 Arawn, is, like Pluto, a plutino, and is forced into this configuration by the gravitational influence of Neptune.[14] This dynamical behavior is recurrent, Arawn becomes a quasi-satellite of Pluto every 2.4 Myr and remains in that configuration for nearly 350,000 years.[14][15][16]