Ice and Carbon on Asteroids
Scientists using a NASA funded telescope have detected water ice and carbon based organic compounds on the surface of an asteroid. The cold facts of the discovery of the frosty mixture on one of the asteroid belt's larger occupants, suggests that some asteroids, along with their celestial brethren, comets, were the water carriers for a primordial Earth. The research is published in today's issue of the journal Nature. These findings may give clues as to how the primordial oceans and life on Earth once formed.
What lies beyond our world is not easy to detect. Still what is out there in the outer solar system may give clues as to how the solar system first formed and how life arose on Earth.
University of Central Florida researchers have detected a thin layer of water ice and organic molecules on the surface of 24 Themis, the largest in a family of asteroids orbiting between Mars and Jupiter. This asteroid is 297 million miles distant from the Sun.
Carbon bearing asteroids are well known. The asteroid belt between Mars and Jupiter consists primarily of three categories of asteroids: C-type or carbonaceous asteroids, S-type or silicate asteroids, and M-type or metallic asteroids.
Carbonaceous asteroids, as their name suggests, are carbon rich and dominate the belt's outer regions. Together they comprise over 75% of the visible asteroids. They are more red in hue than the other asteroids and have a very low albedo. Their surface composition is similar to carbonaceous chondrite meteorites. Chemically, their spectra match the primordial composition of the early Solar System, with only the lighter elements and volatiles removed.
The current unexpected findings (unexpected because a surface layer of ice would have been expected to have "boiled" off over the billions of years since the solar system began.) will be published Thursday, April 29 in Nature, which will feature two complementary articles by the UCF-led team and by another team of planetary scientists.
It has been speculated that free water or ice might exist in the asteroid belt. The present findings confirm this fact. Somewhere in this belt it has been theorized is the point where ice will not form (snow belt).
Some solar system formation theories suggest asteroids brought water to Earth after the planet formed dry. Scientists say the salts and water that have been found in some meteorites (and now perhaps the asteroids) support this view. Comets, which spend more of their time in the outer and far colder regions of the system, are more likely to have volatiles such as water/ice.
Researchers were surprised to find ice and carbon based compounds evenly distributed on 24 Themis. More specifically, the discovery of ice is unexpected because surface ice should be short lived on asteroids, which are expected to be too warm for ice to survive for long.
The second article posted on Themis is the result of six years of observing asteroid by astronomer Andrew Rivkin of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. Rivkin, along with Joshua Emery, of the University of Tennessee in Knoxville, employed the NASA Infrared Telescope Facility to take measurements of the asteroid on seven separate occasions beginning in 2002. Buried in their compiled data was the consistent infrared signature of water ice and carbon-based organic materials.
For further information: http://www.eurekalert.org/pub_releases/2010-04/uocf-aim042810.php or http://www.jpl.nasa.gov/news/news.cfm?release=2010-142&rn=news.xml&rst=2581