'It's not an asteroid': Harvard scientist disputes NASA chief over mysterious space object

A Harvard astrophysicist behind the theory that a mysterious object speeding through the solar system could actually be a lost Soviet spacecraft is pushing back on NASA's top official, saying the object is 'not an asteroid.'

Known as 1998 KY26, the roughly 36-foot-wide object is believed to be a near-Earth asteroid, but it is accelerating in a way that gravity alone cannot explain. Harvard astrophysicist Avi Loeb and his colleagues have examined whether it could instead be Phobos 1, a Soviet spacecraft that stopped communicating while travelling to Mars in 1988.

NASA Administrator Jared Isaacman weighed in on the mysterious object on Thursday during an appearance on 'Fox & Friends.' 'I've not seen any evidence to suggest this is anything other than an asteroid,' Isaacman said.

Loeb challenged that assessment in an interview with Fox News Digital on Friday. '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 said.

Scientists have been trying to explain what is causing the additional acceleration. One theory has been that KY26 is a 'dark comet,' a rocky object behaving like a comet without producing a visible cloud or tail. New research from Georgia Tech has cast doubt on whether KY26 could retain enough ice to produce that effect, while other research has suggested that pressure from sunlight and heat radiating from its surface could account for the acceleration.

Loeb told Fox News Digital that his team found KY26's trajectory closely resembles that of the failed Soviet mission, and calculated that sunlight reflecting off Phobos 1 could produce a push consistent with the non-gravitational acceleration observed in KY26. He also pointed to recent observations indicating the object is highly reflective and rotates about once every five minutes.

The lack of a visible cometary tail or evidence of material escaping the object is central to Loeb's scepticism of the dark-comet explanation. 'It could be a comet shedding some gas backward that is pushing it forward, but in that case we should have seen the gas,' Loeb said. 'We should have seen the dust because for comets we see a tail and the dust particles are being pushed away from the sun by the solar radiation.' He added: 'We don't see a cometary tail. We don't see any evidence for outgassing around this object. That's the puzzle.'

Loeb compared the debate over how to classify KY26 to encountering an unfamiliar animal at a zoo. 'If you are an expert on zebras and you see an elephant, you would say the elephant is a zebra without stripes,' Loeb said. 'But that's an oxymoron because it's a completely different animal.'

Loeb also argued that scientists should be willing to consider explanations outside the familiar categories of asteroids and comets when observations do not neatly fit either one. 'Innovation in science requires some imagination,' he said. 'It requires you to allow for the possibility that our knowledge is incomplete.' Fox News Digital reached out to NASA for a response to Loeb's comments and asked whether Isaacman stands by his assessment of KY26.