A Harvard astrophysicist who has suggested that a puzzling object in the solar system may be a lost Soviet spacecraft is disputing NASA Administrator Jared Isaacman’s view that it is an asteroid.
The object, known as 1998 KY26, is about 36 feet across and is generally classified as a near-Earth asteroid. But it appears to be accelerating in a way that gravity alone does not explain. Avi Loeb and his colleagues have proposed that it could be Phobos 1, a Soviet probe that lost contact with Earth in 1988 while on its way to Mars.
Isaacman said Thursday that he had seen no evidence the object was anything other than an asteroid. Loeb challenged that conclusion in an interview the following day.
“First of all, it’s not an asteroid,” Loeb said, arguing that the object’s apparent acceleration suggests it is being acted on by a force beyond gravity. Asteroids, he said, are simply rocks.
Researchers have offered several possible explanations for the extra acceleration. One is that KY26 could be a dark comet: a rocky body that behaves like a comet but shows no obvious cloud or tail. Recent work by Georgia Tech researchers has raised questions about whether the object could hold enough ice to behave that way. Other studies suggest sunlight or heat radiating from its surface might produce the observed effect.
Loeb said his team found that KY26’s path through space closely resembles the route of the failed Soviet mission. They also calculated that sunlight reflecting off Phobos 1 could create a force consistent with the object’s acceleration. Loeb pointed to observations suggesting KY26 is highly reflective and completes a rotation roughly every five minutes.
For Loeb, the absence of a visible tail or escaping material is a major problem for the dark-comet theory. A comet shedding gas might be pushed forward, he said, but researchers would expect to detect the gas or dust. Neither has been observed around KY26.
He compared the difficulty of classifying the object to seeing an unfamiliar animal and trying to fit it into a category one already knows. Scientists, he argued, should consider explanations beyond the usual labels when the evidence does not fit neatly.
“Innovation in science requires some imagination,” Loeb said. “It requires you to allow for the possibility that our knowledge is incomplete.”
Loeb acknowledged that the spacecraft explanation has not been proved. A possible answer may come in 2031, when Japan’s Hayabusa2 mission is expected to reach KY26.
Loeb said the encounter could reveal that the object is a remnant of Soviet space history rather than a natural body. He joked that the probe might find a label reading “Made in the USSR.” But he also said the theory would be disproved if Hayabusa2 reaches the object and finds an ordinary rock or ice body.
