Asteroid 469219 Kamoʻoalewa, discovered in 2016, is a “quasi-moon” of Earth. Although it is in a heliocentric orbit, its orbital eccentricity and inclination causes it, as observed from the Earth, to appear to orbit the Earth, approaching as close as 5.2 million kilometres, or 13.6 times the mean distance of the Moon. Orbital calculations indicate it has been in this orbit for at least a century and will remain stable for centuries in the future.
A paper in Nature, “Lunar-like silicate material forms the Earth quasi-satellite (469219) 2016 HO₃ Kamoʻoalewa” reports spectral analysis indicated its composition most closely resembles silicate material found on the Moon, which suggests it might consist of material ejected from the Moon in an impact.
China plans to launch a mission in 2024 which will rendezvous with the asteroid in 2025, collect material from the surface, and return it to the Earth, according to an article in IEEE Spectrum, “ China Plans Near-Earth Asteroid Smash-and-Grab”.
