Science & Tech · Space · 11 hrs ago
Study questions whether ice explains 1998 KY26's unexplained acceleration
Near-Earth object 1998 KY26 is accelerating in a way that gravity alone does not explain.
Researchers first suggested that hidden ice could turn into gas and push the object, like a weak rocket.
A new study finds it is too warm to keep water ice for long, making that explanation unlikely.
The researchers instead describe it as probably a dry asteroid, but their study does not explain the acceleration.
Harvard astrophysicist Avi Loeb suggests it could be the lost Soviet Phobos 1 spacecraft, though his study has not been peer-reviewed.
NASA chief Jared Isaacman said he had no evidence that the object is a threat or anything other than an asteroid.
The object is expected to pass about 16 million kilometres from Earth in May 2039, more than 40 times the distance to the Moon.
A new study questions whether ice can explain the unexplained acceleration of near-Earth object 1998 KY26.
The Georgia Institute of Technology researchers conclude that the object is probably too warm to retain water ice for long.
Their study does not provide a new explanation, but points to an earlier proposal involving solar radiation pressure and heat emission.
Harvard astrophysicist Avi Loeb argues instead that 1998 KY26 could be the lost Soviet Phobos 1 spacecraft, a claim based on an unreviewed study.
NASA chief Jared Isaacman said he had no evidence that the object is a threat or anything other than an asteroid.
- Who
- Two aerospace engineers at the Georgia Institute of Technology studied the object. Harvard astrophysicist Avi Loeb has proposed a different explanation.
- What
- A study questions whether water ice could drive 1998 KY26’s unexplained acceleration. It does not establish the cause.
- When
- The study was published in Icarus; the article was published on November 13, 2026.
- Where
- The object is in space, orbiting the Sun.
- Why
- The object’s motion cannot be explained by gravity alone, and researchers are examining possible causes.
Georgia Institute of Technology study authors
Avi Loeb and co-authors
Identity and ice hypothesis
Georgia Institute of Technology study authors
The study authors say 1998 KY26 is probably a dehydrated asteroid and that it is too warm to retain ice for long.
Avi Loeb and co-authors
Loeb argues that 1998 KY26 is the lost Soviet spacecraft Phobos 1.
Explanation of acceleration
Georgia Institute of Technology study authors
The study does not offer its own explanation and points to an earlier proposal involving solar radiation pressure and heat emission.
Avi Loeb and co-authors
Loeb and his co-authors attribute the acceleration to sunlight’s radiation pressure on the body and the spacecraft’s solar panels.
The Soviet Mars probe Phobos 1 was launched.
Phobos 1 was lost after an erroneous control command.
Researchers used about 25 years of telescope data to find that 1998 KY26’s motion differed from what the gravity of the Sun and planets would predict.
The Georgia Institute of Technology study questioning the ice explanation was reported as published in Icarus.
1998 KY26 is expected to pass within about 16 million kilometres of Earth.
- Object
- 1998 KY26
- Estimated size
- About 11 metres
- Distance from Earth
- About 300 million kilometres
- Predicted close approach
- About 16 million kilometres from Earth in May 2039
- Ice temperature threshold
- Water ice would need to remain below about −128°C to persist in space for a long time
- Hypothetical ice loss
- A reserve equal to 1% of the object’s mass would be lost in just over 2,000 years; if it caused the acceleration, in about 62 years
What people are saying
We have found that 1998 KY26 is probably a dehydrated asteroid
The similarity of the orbit of 1998 KY26 to the orbit of the lost spacecraft Phobos 1 suggests that the two objects are identical.
I have no evidence that the object is a threat or anything other than an asteroid.