In 2031, Japan’s Hayabusa2 spacecraft will arrive at the near-Earth asteroid 1998 KY26: a tiny body that is accelerating in a way that astronomers have struggled to explain. Some studies have suggested that the asteroid is pushed along by water escaping from it as gas, making it an as-yet theoretical “dark comet.”

But through new simulations, Korbin Hansen and Masatoshi Hirabayashi at the Georgia Institute of Technology show that the asteroid is far too warm to hold on to ice, pouring cold water on the idea that comet-like accelerations could occur without a visible cloud.

Their findings have been published in Icarus.