Scientists finds water ice on asteroid’s surface

Washington, April 29 ( Asteroids may not be the dark, dry, lifeless chunks of rock. According to recent research, there is evidence of water ice and organic material on the asteroid 24 Themis.

The research led by Josh Emery, assistant professor with the earth and planetary sciences department at the University of Tennessee (UT), found evidence that supports the idea that asteroids could be responsible for bringing water and organic material to earth.

Using NASA’s Infrared Telescope Facility on Hawaii’s Mauna Kea, Emery and Andrew Rivkin of Johns Hopkins University in Laurel examined the surface of 24 Themis, a 200-km wide asteroid that sits halfway between Mars and Jupiter.

By measuring the spectrum of infrared sunlight reflected by the object, the researchers found the spectrum consistent with frozen water and determined that 24 Themis is coated with a thin film of ice. They also detected organic material.

“The organics we detected appear to be complex, long-chained molecules. Raining down on a barren earth in meteorites, these could have given a big kick-start to the development of life,” Emery said.

Emery noted that finding ice on the surface of 24 Themis was a surprise because the surface was too warm for ice to stick around for a long time.

“This implies that ice is quite abundant in the interior of 24 Themis and perhaps many other asteroids. This ice on asteroids may be the answer to the puzzle of where earth’s water came from,” he said.

Still, how the water ice got there is unclear. 24 Themis’ proximity to the sun causes ice to vapourise.

However, the researchers’ findings suggest the asteroid’s lifetime of ice ranges from thousands to millions of years depending on the latitude.

Therefore, the ice is regularly being replenished.

The scientists theorize this is done by a process of “outgassing” in which ice buried within the asteroid escapes slowly as vapour migrates through cracks to the surface or as vapour escapes quickly and sporadically when 24 Themis is hit by space debris.

Since Themis is part of an asteroid “family” that was formed from a large impact and the subsequent fragmentation of a larger body long ago, this scenario means the parent body also had ice and has deep implications for how our solar system formed.

The discovery of abundant ice on 24 Themis demonstrates that water is much more common in the Main Belt of asteroids than previously thought, said an UT release.

The findings were detailed in the Thursday issue of Nature.