Overview
- 1998 KY26 is a roughly 11‑meter near‑Earth object that spins once every about 5.35 minutes and shows a measurable non‑gravitational acceleration that gravity alone cannot explain.
- A team led by Adam Hibberd, Adam Crowl and Abraham Loeb proposed in September 2026 that the object could match models of the long‑lost 1988 Soviet probe Phobos 1, based on lightcurves and radiation‑pressure fits.
- In November 2026 Korbin Hansen and Masatoshi Hirabayashi published thermal models in Icarus showing internal temperatures too high to preserve water ice over long timescales, which weakens the buried‑ice 'dark comet' outgassing explanation.
- JAXA’s Hayabusa2 is scheduled to rendezvous with 1998 KY26 in July 2031 and that in‑situ encounter is expected to provide the decisive data to determine whether the object is natural or artificial, while NASA officials say there is no evidence it poses an impact threat.
- Because the object is very small, rapidly rotating and sparsely observed, remote data remain ambiguous and researchers say direct measurements from Hayabusa2 will be needed to settle the origin and the physical cause of its anomalous motion.