A mysterious 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 four decades ago.
Known as 1998 KY26, the object is about 36 feet across and is generally classified as a near-Earth asteroid. Yet something besides gravity appears to be influencing its trajectory. New research has challenged one theory about what may be causing that unexpected motion.
NASA Administrator Jared Isaacman addressed the speculation Thursday morning on “Fox & Friends.” He said some members of the UAP community believe the object is behaving unusually, but he has seen no evidence that KY26 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 unusual change in motion as “nongravitational acceleration.” In other words, a force beyond the gravitational pull of the sun and planets appears to be affecting its path.
One proposed explanation is that KY26 could be a “dark comet” containing water beneath its surface. If that ice were turning into gas, the escaping material could propel the object through space. Astronomers, however, have not observed the cloud or tail typically linked to comet activity.
A new peer-reviewed study from Georgia Institute of Technology researchers Korbin Hansen and Masatoshi Hirabayashi has now raised further questions about that theory.
Published in the journal Icarus, the study concluded that KY26 is probably too warm for subsurface water ice to remain intact long enough to explain the object’s unusual acceleration.
Two shape models depict scientists’ estimates of the near-Earth object’s form. (Credit: NASA)
The researchers wrote that the calculated rates of water loss “preclude 1998 KY26 being a dark comet at present.”
Other explanations remain possible. Earlier research suggested that sunlight striking KY26 and heat radiating from its surface could generate the additional force without requiring buried water ice.
Another team, meanwhile, has investigated a much more unconventional possibility.
Harvard astrophysicist Avi Loeb, along with researchers Adam Hibberd and Adam Crowl, has 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 roughly 36 feet across, reflects about 52% of the sunlight that reaches it and rotates once every 5.35 minutes.
The researchers created a simplified model of Phobos 1 and compared its predicted sunlight reflections during rotation with observations of KY26. The spacecraft model closely matched eight separate sets of observations.
They also modeled the effect of sunlight pressing against a cylindrical body or solar panels. That analysis produced a closer match to hundreds of telescope and radar observations of KY26.
“Although an investigation of this kind cannot be conclusive,” the researchers wrote, the results “add strong weight to the Phobos 1 hypothesis.”
Still, the researchers emphasized that their model does not establish that KY26 is the missing spacecraft. They described the idea as “strongly plausible but presently unproven.”
Other studies point toward a more conventional explanation.
A separate study published this year in Astronomy & Astrophysics analyzed light reflected from KY26 and found that its composition appears consistent with a rocky asteroid. The researchers concluded that the object probably originated in the inner region of the asteroid belt.
Isaacman said NASA is continuing to track KY26, but the agency has no reason to be concerned.
An illustration shows an asteroid passing near Earth as scientists investigate 1998 KY26’s unusual movement and the possibility that it is 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.
Scientists could eventually obtain a definitive answer.
The Japan Aerospace Exploration Agency’s Hayabusa2 spacecraft is scheduled to rendezvous with KY26 in July 2031, according to a 2025 study published in Nature Communications.
For Loeb, that encounter could offer the most decisive 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.
