A puzzling object racing through the solar system is accelerating in a way that gravity alone cannot explain, prompting speculation that it may be a Soviet spacecraft lost nearly 40 years ago.
The object, known as 1998 KY26, is an approximately 36-foot-wide near-Earth asteroid. However, forces beyond the gravitational pull of the sun and planets appear to be altering its trajectory. New research has challenged one of the leading explanations for that motion.
NASA Administrator Jared Isaacman addressed the speculation Thursday on “Fox & Friends.” He said some members of the UAP community believe KY26 is moving unusually, but he has seen no evidence that it is anything other than an asteroid.
“First of all, nothing is about to hit us, to be very clear on this,” Isaacman said. “I’ve not seen any evidence to suggest this is a threat to our planet or anything other than an asteroid.”
NASA Administrator Jared Isaacman speaks at a Senate hearing in Washington, D.C. (REUTERS)
Scientists describe KY26’s strange motion as “nongravitational acceleration,” a term used when an object’s path is being influenced by something beyond the gravitational forces of the sun and planets.
One possibility is that KY26 is a “dark comet” containing subsurface water. If that water turns into gas, it could act like a small thruster and propel the object through space. Astronomers, however, have not observed the cloud or tail typically produced by a comet.
A new peer-reviewed study from Georgia Institute of Technology researchers Korbin Hansen and Masatoshi Hirabayashi has now weakened that theory.
Published in Icarus, the study concluded that KY26 is probably too warm for buried water ice to remain intact long enough to produce the observed acceleration.
Two shape models represent scientists’ estimates of near-Earth object 1998 KY26. (Credit: NASA)
The researchers wrote that the estimated rate of water loss “preclude 1998 KY26 being a dark comet at present.”
Other explanations remain possible. Earlier research suggested that sunlight striking KY26, combined with heat radiating from its surface, could generate the additional force without requiring buried water.
Another team, meanwhile, has investigated a much more unconventional explanation.
Harvard astrophysicist Avi Loeb and researchers Adam Hibberd and Adam Crowl have considered whether KY26 might be Phobos 1, an unmanned Soviet spacecraft that lost contact while en route to Mars in 1988.
An illustration depicts the Soviet Phobos 1 spacecraft, launched toward Mars in July 1988 before a faulty command caused it to shut down. (Credit: NASA)
KY26 measures about 36 feet across, reflects approximately 52% of the sunlight that reaches it and rotates once every 5.35 minutes.
The researchers created a simplified Phobos 1 model and compared its changing sunlight reflections as it rotated with observations of KY26. The spacecraft simulation closely matched eight separate observation sets.
They also modeled how sunlight might push against a cylinder or solar panels. That analysis matched hundreds of telescope and radar observations more closely than the asteroid models.
“Although an investigation of this kind cannot be conclusive,” the researchers wrote, their results “add strong weight to the Phobos 1 hypothesis.”
The team emphasized that the findings do not establish KY26 as the missing spacecraft. Instead, they described the idea as “strongly plausible but presently unproven.”
Still, other studies support a more ordinary explanation.
A separate paper published this year in Astronomy & Astrophysics analyzed the light reflected from KY26 and found that its composition appears consistent with a rocky asteroid. The researchers concluded that the object likely originated in the inner asteroid belt.
Isaacman said NASA is continuing to track KY26 and sees no reason for concern.
An illustration shows an asteroid passing near Earth as scientists investigate the unusual motion of 1998 KY26 and its possible connection to a long-lost Soviet spacecraft. (istock)
“I have no reason to believe this is in any way remotely a threat to our planet or anything other than just an asteroid,” he said.
A definitive answer could eventually come from a spacecraft encounter.
The Japan Aerospace Exploration Agency’s Hayabusa2 mission is scheduled to rendezvous with KY26 in July 2031, according to a 2025 study published in Nature Communications.
For Loeb, that mission could offer the clearest test yet of the Phobos 1 theory.
“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.