Frozen asteroid

Ice confirmed on 24 Themis

Ice has been detected on one of the largest-known asteroids in the solar system, a finding now detailed in published reports.

FROSTED ROCK New observations of the asteroid 24 Themis, the large object portrayed here along with two much smaller related objects and the sun in this artist’s illustration, confirm that it’s the first known asteroid to have frozen water on its surface. Gabriel Pérez, Servicio MultiMedia, Instituto de Astrofisica de Canarias, Tenerife, Spain

Science News first reported that frozen water resides on the surface of 24 Themis, an asteroid orbiting in the middle of the asteroid belt, last October when the work was presented at a conference. Now the two teams cited in the original article — Humberto Campins of the University of Central Florida in Orlando and his collaborators, and Andrew Rivkin of Johns Hopkins University’s Applied Physics Laboratory in Laurel, Md., and Joshua Emery of the University of Tennessee in Knoxville — have both published their findings in the April 29 Nature.

Read the original article here.

Planetary scientist Henry Hsieh of Queen’s University Belfast notes that the new findings mean that planetary scientists can now directly the measure the abundance of ancient asteroid water that may have been the source of Earth’s oceans rather than having to estimate the amount from the hydrated minerals found in some meteorites. “Investigation of the chemical and isotopic composition of main-belt asteroid ice by either ground-based telescopes or spacecraft will allow comparison with terrestrial water, yielding a bounty of insights into this ancient water source,” he notes in a commentary accompanying the articles published by the Campins group and Rivkin and Emery in the same issue of Nature.

“Stay tuned,” Hsieh says. “The story is just beginning.”

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