Asteroid 1998 KY26 spins every 5.35 minutes and accelerates perpendicular to its orbital plane, defying expectations, while measuring just 11 meters across. The space rock behaves unlike typical asteroids pushed solely by predictable solar forces. Aerospace engineers Korbin Hansen and Masatoshi Hirabayashi of the Georgia Institute of Technology published these findings in Icarus.
Scientists previously hypothesized that 1998 KY26 might be a dark comet. Dark comets masquerade as ordinary asteroids while using invisible outgassing to propel themselves along altered trajectories. However, thermal modeling by the Georgia Institute of Technology researchers indicates the object is too warm to hold the volatile ice required for such propulsion.
Thermal Modeling Excludes Buried Ice
Water ice needs temperatures below around 145 Kelvin (-128 degrees Celsius) to survive over long periods in space. Hansen and Hirabayashi calculated that even the coldest regions on 1998 KY26 maintain an average temperature of at least 212 Kelvin (-61 degrees Celsius) throughout its orbit. At that heat level, any water ice making up 1 percent of the asteroid’s mass would vanish in just over 2,000 years.
Our temperature model results indicate that the water outgassing rate on 1998 KY26 would be too high to maintain buried ice, refining the understanding of the asteroid’s composition,
Hansen and Hirabayashi wrote in their published paper. If ice drove the asteroid’s observed acceleration, it would deplete entirely in a mere 62 years.
Solar Radiation Pressure Drives Asteroid Acceleration
With the dark-comet explanation challenged by thermal calculations, researchers point toward solar radiation pressure as a possible driver behind the acceleration. Sunlight exerts a continuous force capable of nudging small bodies off course. An earlier paper also traced the object’s potential origins back to the main asteroid belt, further diminishing the likelihood of cometary activity.
Researchers captured an actual photo of 1998 KY26 in 2025 using the Gemini South telescope, showing the object as a tiny white dot. The Japanese space agency’s Hayabusa2 spacecraft is currently traveling toward the asteroid, with a scheduled rendezvous slated for July 2031.
Frequently Asked Questions About 1998 KY26
How large is asteroid 1998 KY26?
The space rock measures approximately 11 meters or 36 feet across. It rotates once every 5.35 minutes.
When will spacecraft arrive at the asteroid?
The Japanese space agency’s Hayabusa2 spacecraft is scheduled to reach 1998 KY26 for a close-up rendezvous in July 2031.
What temperatures does the asteroid reach?
Even the coldest regions on 1998 KY26 average at least 212 Kelvin (-61 degrees Celsius) over the course of its orbit around the Sun.
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