Asteroid 1998 KY26 is accelerating in a way gravity cannot explain.
Asteroid 1998 KY26 Accelerates
Discovered in 1998, the near-Earth object measures 36 feet across and rotates every 5.35 minutes. Astronomers track non-gravitational acceleration in its trajectory. Forces other than the Sun and planets influence its path. The puzzle involves accelerations larger than those normally produced by the Yarkovsky effect.
Sunlight provides a gentle push that can slowly reshape an orbit. Objects absorb solar radiation and release it as heat. This provides a small force that can affect an orbit over time.
NASA Administrator Jared Isaacman addressed the mysterious trajectory during an appearance on “Fox & Friends.”
“I’ve not seen any evidence to suggest this is…anything other than an asteroid,” said Isaacman. He said that NASA continues to monitor the object. He sees no reason for alarm. He explained that he has no reason to believe it poses any threat to our planet.
Harvard Researcher Challenges NASA
Avi Loeb challenged Isaacman’s assessment in an interview with Fox News. He argued that the object’s movement disqualifies it from being a simple space rock.
“Well, first of all, it’s not an asteroid because 1998 KY26 appears to have non-gravitational acceleration, meaning it’s being pushed by some force other than gravity,” Loeb said. “And asteroids are just rocks.”
Loeb and colleagues Adam Hibberd and Adam Crowl examined whether 1998 KY26 could be Phobos 1. The unmanned Soviet spacecraft launched on July 7, 1988, and lost communication on its way to Mars. The researchers calculated that sunlight reflecting off the probe’s metallic surfaces and solar panels could generate radiation pressure.
This pressure is consistent with the acceleration observed in KY26. Their study found that the model matched eight separate sets of observations. The object reflects almost 52% of the sunlight that hits it.
Researchers Doubt Comet Theory
Earlier studies proposed that 1998 KY26 might be a dark comet containing buried ice. The ice turns to gas and provides a propulsion thrust. New research in the journal Icarus by Georgia Institute of Technology researchers Korbin Hansen and Masatoshi Hirabayashi casts doubt on that premise.
The team modeled the object’s temperatures. Even its coldest regions average at least 212 Kelvin, or minus 78.7 degrees Fahrenheit. Water ice requires temperatures below 145 Kelvin to remain stable over geological timescales.
Here, we show that all locations on the surface or in the interior of 1998 KY26 have orbit-averaged temperatures significantly above the sublimation point of volatiles in vacuum.
Korbin Hansen and Masatoshi Hirabayashi, researchers
The researchers added that any subsurface ice would deplete too rapidly to sustain continuous outgassing. They pointed instead to a dehydrated asteroid. Solar radiation pressure and thermal emission forces may influence its movement.
Rendezvous Scheduled for July 2031
Definitive answers may arrive when the Japan Aerospace Exploration Agency’s Hayabusa2 spacecraft reaches the target.
“Our prediction is that instead of an iceberg, Hayabusa 2’s cameras will reveal the label ‘Made in the U.S.S.R.,’” Loeb wrote.