2023-05-15 20:08:00
The asteroid Kamo’oalewa orbits the earth like a second moon. The clues are growing: The asteroid might once have been part of the moon.
Frankfurt – The moon is not the only celestial body orbiting the earth. Several so-called quasi-moons do this as well, and research has only just found the newest of these mini-moons. It has been known since 2016 that the asteroid (469219) Kamo’oalewa is also orbiting the earth. As early as 2021, a research team suggested that Kamo’oalewa must be related to the moon. A new study now supports this theory.
In 2021, a research group led by astrophysicist Benjamin Sharkey (University of Arizona) found that Kamo’oalewa’s material most closely resembles the rock that NASA astronauts brought from the moon to Earth on the Apollo 14 mission. The research team that published the latest study on Kamo’oalewa took a different approach and looked at its orbit. “Given its Earth-like orbit and its physical resemblance to lunar surface materials, we investigate the hypothesis that Kamo’oalewa may have formed as a debris fragment from a meteorite impact on the lunar surface,” reads the paper by Jose Daniel Castro-Cisneros (University of Arizona) and two colleagues. The study was published on the preprint server arXiv and not yet checked by experts.
New study: Is the asteroid Kamo’oalewa a fragment of the moon?
For their study, the three researchers developed computer models that they used to investigate how particles behave that are knocked out of the moon by a collision. Most of the particles in the simulation left the vicinity of the Earth and Moon and moved in orbits around the Sun – which is unsurprising given that the Sun’s gravity affects everything in the solar system.
All of the particles that took orbits similar to those of Kamo’oalewa in the simulation had one thing in common: their launch velocity. “The most favorable conditions are launch velocities slightly above the escape velocity from the moon’s rear hemisphere,” the paper states.
The moon is riddled with craters – one of which might be from Kamo’oalewa
The fragments of the moon orbiting the earth in the simulation had speeds of more than 2.4 kilometers per second (8640 km/h). Researchers know that impacts on the moon occur at speeds of up to 55 kilometers per second. At impacts with these speeds, fragments can travel up to 6 kilometers per second – much faster than they need to reach a Kamo’oalewa-like orbit. So it’s entirely possible that a meteorite knocked a piece out of the moon, which then landed in Earth orbit.
Numerous craters exist on the moon – one of them may have been formed when Kamo’oalewa was ejected from the moon by a meteorite. However, it is still unclear which crater is suitable. “We leave it to a separate study to examine whether a lunar crater of appropriate size, age, and geographic location is consistent with the lunar ejection hypothesis for the origin of Kamo’oalewa,” the researchers write.
China plans space mission to Kamo’oalewa
Solid evidence of Kamo’oalewa’s origins might reach Earth in the next few years: China wants to launch the “Tianwen 2” mission in 2025, which is intended to head for Kamo’oalewa. The Chinese spacecraft is said to take soil samples and even land on the small celestial body before returning the samples to Earth. By then at the latest, research should find out whether Kamo’oalewa is actually a fragment of the moon. (tab)
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