# Hayabusa2 Target Too Warm for Ice, Deepening Acceleration Mystery

> Japan's Hayabusa2 probe faces a mystery as its next asteroid target is too warm to hold ice, deepening the unexplained acceleration puzzle.
- Title: Hayabusa2 Target Too Warm for Ice, Deepening Acceleration…
- Summary: Japan's Hayabusa2 probe faces a mystery as its next asteroid target is too warm to hold ice, deepening the unexplained acceleration puzzle.
- Keywords: hayabusa2, 1998 ky26, ryugu, jaxa, icarus, yarkovsky effect, dark comet, apollo-class asteroid, markets, BigGo Finance
- Source: BigGo Finance — https://finance.biggo.com/news/1c6ca74a-de92-4706-bad0-bd872b1e8458
- Author: BigGo Finance
- Published: 2026-11-10T19:25:12+00:00
- Read time: 1 min
- Topics: hayabusa2, 1998 ky26, ryugu, jaxa, icarus, yarkovsky effect, dark comet, apollo-class asteroid, finance, markets
## Asteroid 1998 KY26
A new study in the journal Icarus finds the asteroid is too warm to retain buried water ice.

> Here, we show that all locations on the surface or in the interior of 1998 KY26 have orbit-averaged temperatures significantly above the sublimation point of volatiles in vacuum
## Temperature Thresholds
Even its coldest regions average at least 212 Kelvin, well above the threshold for ice survival.
## Dark Comet Theory
The object was proposed as a dark comet after a 2023 paper found accelerations exceeding the Yarkovsky effect.
## Ice Survival Challenge
Water ice needs temperatures below roughly 145 Kelvin to survive for long stretches.
## Hayabusa2 Mission Timeline
Hayabusa2 returned samples from Ryugu in 2020 and is due to reach 1998 KY26 in July 2031.
## Asteroid Characteristics
1998 KY26 is about 11 meters wide and rotates roughly every five minutes.
## Accelerating Mystery
The puzzle dates to 2023 when a study reported non-gravitational accelerations larger than the Yarkovsky effect.
## Mission Challenges
1998 KY26 is smaller and spins faster than expected, complicating Hayabusa2's landing attempt.
## Key takeaway

Asteroid 1998 KY26 is too warm to retain buried water ice, undermining the dark comet theory for its odd acceleration.