Asteroid 1998 KY26 Too Warm to Hold Ice
Researchers say the small asteroid's temperatures are too high for buried water ice to persist, challenging an explanation for its unusual motion.
Updated on Nov. 7, 2026 in Space
Researchers found that asteroid 1998 KY26, which is 11 meters (36 feet) across, is too warm to retain the water ice that could power its propulsion. The Hayabusa2 spacecraft is traveling toward the asteroid and is expected to rendezvous with it in July 2031.
Why it matters
The asteroid shows unusual acceleration perpendicular to its orbital plane, and ice was a candidate explanation. Ruling it out leaves open whether the motion comes from undetected outgassing, as a dark comet would produce.
Temperature models place the coldest regions of the 11-meter asteroid at an average of at least 212 Kelvin, far above the roughly 145 Kelvin at which buried water ice can survive. The model's inputs are based on known size, orbit, reflectivity and likely composition, and the actual surface and interior conditions have not been directly measured.
The players
Hayabusa2
Hayabusa2 is a Japanese Aerospace Exploration Agency spacecraft that previously returned samples from the asteroid Ryugu and is now traveling toward KY26.
Georgia Institute of Technology
Georgia Institute of Technology is a public research university in Atlanta, Georgia, whose aerospace engineers conducted the study.
The details
Researchers at the Georgia Institute of Technology, Korbin Hansen and Masatoshi Hirabayashi, combined known data on KY26's size, orbit, reflectivity and likely composition to model its temperatures. The asteroid rotates once every 5.35 minutes, and the team's calculations indicate that any ice would not persist long enough to drive the acceleration observed.
Timeline
July 2031: Hayabusa2 is scheduled to rendezvous with asteroid 1998 KY26.
The Big Picture
The Hayabusa2 mission, which returned samples from the asteroid Ryugu, is now headed toward KY26, extending the program to a second small body. Ruling out buried ice on KY26 narrows the possible explanations for its acceleration and makes the rendezvous a direct test of whether it is a dark comet.
Findings like these refine how scientists track and classify small near-Earth objects, which informs future planetary defense and mission planning. The reader-facing relevance is limited to understanding how spacecraft are used to test theories about small bodies.
The takeaway
Ruling out ice as the source of KY26's acceleration shows how temperature modeling can narrow down explanations for unusual asteroid behavior. A direct spacecraft encounter in 2031 will be needed to confirm which explanation holds.
What happens next
Hayabusa2 is scheduled to rendezvous with asteroid 1998 KY26 in July 2031, when researchers may be able to test the asteroid's physical properties directly.
Further reading
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