China's Tianwen-2 spacecraft has successfully reached Kamoʻoalewa, a small asteroid that keeps pace with Earth, and returned the first close-range image of the object. This achievement is remarkable, considering the spacecraft's long journey of 400 days and 1 billion kilometres. However, the image itself does not provide a definitive answer to the question of Kamoʻoalewa's origin. The leading theory suggests that it is a fragment blasted from the Moon, but new evidence challenges this idea.
One of the main challenges to the lunar-fragment hypothesis is a peer-reviewed population study that modelled both ordinary near-Earth asteroids delivered from the main belt and fragments from the Giordano Bruno impact. The study found that the main-belt origin is more likely, with an average of 1.23 plus or minus 0.13 Kamoʻoalewa-like objects from the main-belt population, compared with 0.042 from Giordano Bruno ejecta. This calculation favours a main-belt origin by more than an order of magnitude, but it is a population argument and does not trace this particular asteroid backwards to a known parent.
Another challenge concerns the spectrum itself. A May 2026 Nature Communications paper reanalysed the absorption feature and found it consistent with LL chondrites, the stony material associated with asteroids such as Itokawa. In laboratory tests, highly space-weathered LL-chondrite powder reproduced Kamoʻoalewa’s reflectance spectrum even though solid pieces did not. The team proposed an origin in the Flora asteroid family, followed by extensive weathering of fine surface material.
A third challenge comes from Sharkey’s new Webb observations. The infrared spectrum measured in February 2026 is much less red than the earlier ground-based result. New Large Binocular Telescope measurements from April agree with Webb. In the preprint, the authors say the colours resemble several silicate asteroid classes more than weathered lunar material, while the albedo and absorption features may fit an oldhamite-bearing, enstatite-rich composition.
These results do not all identify exactly the same asteroid analogue. What they share is that none requires Kamoʻoalewa to be lunar rock. The image cannot settle the origin question, and the returned sample is designed to remove ambiguities created by grain size, space weathering, and viewing geometry. Laboratory measurements can compare its minerals, elemental ratios, and isotopes with lunar samples and known meteorite groups.
In my opinion, the fact that Kamoʻoalewa is a quasi-moon that still orbits the Sun is particularly fascinating. It raises a deeper question about the nature of our solar system and the possibility of other celestial bodies with similar characteristics. Personally, I think that the main-belt origin is more likely, but the sample will provide a definitive answer. What many people don't realize is that the journey of Tianwen-2 is a testament to the power of human ingenuity and the importance of scientific exploration. If you take a step back and think about it, the fact that we can send a spacecraft to chase a tiny quasi-moon for 400 days and 1 billion kilometres is a remarkable achievement that inspires us to push the boundaries of what is possible.
