As reported by euronews.com, an 11-metre-wide body traversing the Solar System has displayed abnormal acceleration, sparking theories that it might be a lost Soviet-era spacecraft from nearly 40 years ago missing nearly 40 years ago.
Known as 1998 KY26, the object is passing near Earth while its trajectory cannot be fully explained by the gravitational pull of the Sun or Earth, euronews.com reported. This unusual behaviour is known as non-gravitational acceleration, meaning forces other than gravity are influencing the object’s path and speed.
NASA Administrator Jared Isaacman said on Thursday that the agency is monitoring KY26 but stressed there is no reason for concern, euronews.com reported. He offered assurances to the general public that there is no recognized danger to Earth and no indication of any impending collision course with the planet.
“I’ve not seen any evidence to suggest this is…anything other than an asteroid,” Isaacman said during an appearance on Fox & Friends, according to Fox News.
Evaluating the Phobos 1 Hypothesis
A group of researchers has put forward an unusual explanation for the trajectory of the 36-foot-wide body. According to euronews.com, Harvard astrophysicist Avi Loeb alongside colleagues Adam Hibberd and Adam Crowl suggest that KY26 may actually be Phobos 1, an uncrewed Soviet probe sent into space on July 7, 1988, which ceased communicating with Earth during its journey toward Mars.
Euronews.com said that the investigators constructed a basic replica of Phobos 1 to evaluate how its sunlight reflection patterns during rotation would measure up against actual data gathered from KY26. They found that the model closely matched eight separate sets of observations of the object.
Data highlighted by euronews.com shows that KY26 rotates completely every 5.35 minutes and has a sunlight reflectivity rate of nearly 52%. Loeb and his colleagues argue that these characteristics are consistent with their hypothesis that KY26 could be an artificial object.
“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, and asteroids are just rocks,” Loeb told Fox News.
Scientists debate whether KY26 is a comet or asteroid
One explanation, first proposed in a 2023 study published in The Planetary Science Journal, is that KY26 is a dark comet containing trapped water that turns into gas, creating thrust as the object moves through space, euronews.com reported. However, astronomers have not detected the cloud of gas or tail normally associated with comets.
A separate scientific study published in Icarus has offered a contrasting explanation. Researchers concluded that 1998 KY26 is most likely a dehydrated asteroid, meaning water ice is unlikely to be responsible for its unusual acceleration because temperatures are too high for sufficient ice to survive over an extended period, euronews.com reported.
Euronews.com pointed out that solar radiation serves as another viable theory, as it is capable of pressing against the object’s exterior and causing minor shifts in its path. In a 2025 publication relayed to Fox News by NASA, the space agency detailed an exhaustive orbital study of near-Earth asteroid 1998 KY26, determining that solar radiation pressure is the driving force behind its movement.
Other observations also point towards a natural, rocky asteroid rather than an old spacecraft, euronews.com reported. A study published in the journal Nature Communications estimated its diameter at just 11 metres.
Hayabusa2 Rendezvous in 2031
A Japanese space mission could eventually provide important answers. Euronews.com reported that the Hayabusa2 probe is scheduled to intercept 1998 KY26 by July 2031 for a close-up examination. It would be the first mission to directly investigate an asteroid of this tiny size.
Euronews.com said that visual data and telemetry gathered during the flyby may finally determine whether the entity is a genuine space rock or a manufactured artifact. Meanwhile, the Daily Mail reported that the European Space Agency expects the object to make an even closer approach in 2039, passing within 10 million miles.
“Our prediction is that instead of an iceberg, Hayabusa 2’s cameras will reveal the label ‘Made in the U.S.S.R.,'” Loeb said.
Frequently Asked Questions
What is the size of 1998 KY26?
The object is approximately 11 metres, or 36 feet, wide, according to observations published in Nature Communications and reported by euronews.com and Fox News.
When was the suspected Soviet probe launched?
Phobos 1 was launched by the former Soviet Union on July 7, 1988, before losing contact with Earth while traveling to Mars, euronews.com reported.
When will the Hayabusa2 spacecraft reach the object?
The Japan Aerospace Exploration Agency’s Hayabusa2 spacecraft is expected to rendezvous with 1998 KY26 in July 2031, euronews.com and Fox News reported.
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