Mysterious object moving through space could be lost Soviet probe as NASA weighs in on theory

Known as 1998 KY26, the roughly 36-foot-wide object is believed to be a near-Earth asteroid, but something other than gravity appears to be affecting its path. Scientists refer to this unusual movement as "nongravitational acceleration," meaning something besides the pull of the sun and planets is affecting its trajectory.

Dark Comet Theory

One theory suggested KY26 might be a "dark comet" containing buried water that turns to gas and gives the object a push through space, even though astronomers have not detected the cloud or tail normally associated with a comet. However, a new peer-reviewed study by Georgia Institute of Technology researchers has cast doubt on this explanation.

The researchers found KY26 is likely too warm for buried water ice to survive long enough to account for the unusual movement. Their study, published in the journal Icarus, concluded that calculated water-loss rates "preclude 1998 KY26 being a dark comet at present."

Soviet Spacecraft Hypothesis

Another group of researchers has explored a far more unusual possibility. Harvard astrophysicist Avi Loeb and researchers Adam Hibberd and Adam Crowl have examined whether KY26 could actually be Phobos 1, an unmanned Soviet spacecraft that stopped communicating while traveling to Mars in 1988.

The researchers built a simplified model of Phobos 1 and compared the way it would reflect sunlight as it spun with observations of KY26. They found the spacecraft model closely matched eight sets of observations of the object. They also tested whether sunlight pushing against a cylinder or solar panels could help explain KY26's movement and found the model better matched hundreds of telescope and radar observations.

NASA's Position

NASA Administrator Jared Isaacman weighed in on the growing speculation, saying some in the UAP community believe the object is making unusual movements, but he has seen no evidence KY26 is anything other than an asteroid.

Future Verification

Scientists may eventually get a definitive answer when 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 provide the ultimate test 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. Other research points to a more conventional answer, with a separate study finding KY26's makeup appears consistent with a type of rocky asteroid likely from the inner part of the asteroid belt.