Overview
- Astronomers have measured 1998 KY26 accelerating in ways not explained by gravity alone, including a component perpendicular to its orbital plane.
- A new paper in Icarus shows KY26’s coldest surface averages about −61°C, far warmer than the ≈−128°C needed to preserve buried water ice, making sustained outgassing unlikely.
- The authors estimate that even if 1% of KY26’s mass were water ice it would be lost in roughly 2,000 years and any sublimation-driven thrust would last only about 62 years.
- KY26 is a tiny fast rotator roughly 11 meters across that spins every 5.35–5.5 minutes, a combination that amplifies effects from solar radiation pressure and thermal-emission forces.
- Japan’s Hayabusa2 is scheduled to rendezvous with KY26 in 2031 to make in‑situ measurements that can confirm its composition and settle which sunlight‑driven mechanism explains the anomalous motion.