Kamo'oalewa asteroid's lunar origin challenged ahead of Tianwen-2 arrival

June 2, 2026 report Kamo'oalewa asteroid's lunar origin challenged ahead of Tianwen-2 arrival Paul Arnold Author Lisa Lock Scientific Editor Robert Egan Associate Editor China's Tianwen-2 sample-return mission is well on its way to its target, an asteroid called Kamo'oalewa. The spacecraft left Earth in May 2025 and should return in late 2027 with samples of a space rock that scientists had assumed originated from the moon. However, a new study published in Nature Communications suggests that we may be mistaken about the asteroid's origin. Kamo'oalewa is a small quasi-satellite orbiting the sun but close to Earth, measuring less than about 300 feet (100 meters) across. This fast-spinning object completes a rotation roughly every 28 minutes and, according to earlier research, may have been created when an ancient impact on the moon blasted a fragment into space. That theory rests in part on its unusually red spectrum, which looks similar to heavily space-weathered lunar soil. However, Yang Li, a planetary scientist at the Chinese Academy of Sciences, and colleagues are challenging that idea after a fresh analysis of the asteroid. First, the researchers reanalyzed its reflected light. They found a characteristic dip in the light spectrum more commonly associated with a type of meteorite known as an LL chondrite than with lunar rock. Blasting meteorite powder with lasers Next, they took an LL chondrite meteorite that had fallen to Earth, ground it into a powder, and blasted it with lasers. This was to simulate millions of years of space weathering, namely micrometeoroid impacts and solar wind. The powder's color changed dramatically and ultimately matched the appearance of Kamo'oalewa. The significance of this is that it suggests asteroid surface material can turn just as red as lunar soil if left in space long enough. It doesn't have to have come from our satellite. Having demonstrated this, the research team then searched catalogs of thousands of known space rocks for other extremely red, rocky bodies. They found several other silicate-rich asteroids with very red spectra, though Kamo'oalewa remains among the most extreme. A possible origin? So if the rock isn't lunar, where does it come from? The team ran orbital flight path models and has an idea, as they explain in their paper. "We, therefore, propose that Kamo'oalewa probably originated from the Flora family and developed an Itokawa-compositional, more space-weathered, fine-regolith-dominated surface." Itokawa is another asteroid and was sampled by a Japanese spacecraft in 2010. Although the scientists point to a different origin for Kamo'oalewa, they're not saying it is definitive. "We emphasize that we support the view that Kamo'oalewa's surface is dominated by highly space-weathered LL chondrite-compositional fine-grained regolith, but do not completely close the door of lunar composition." Written for you by our author Paul Arnold, edited by Lisa Lock, and fact-checked and reviewed by Robert Egan—this article is the result of careful human work. We rely on readers like you to keep independent science journalism alive. If this reporting matters to you, please consider a donation (especially monthly). You'll get an ad-free account as a thank-you. Publication details Pengfei Zhang et al, Tianwen-2 mission target asteroid (469219) Kamoʻoalewa probably develops an Itokawa-compositional but more space-weathered surface, Nature Communications (2026). DOI: 10.1038/s41467-026-73284-w Journal information: Nature Communications © 2026 Science X Network