July 30, 2009

Study: Comets once had watery interiors

Comets held a vast ocean of water in their interiors during the first million years after their formation, a study by a Welsh university says.

The liquid environment of early comets, along with the large quantity of organic matter already discovered, would have provided great culture for primitive bacteria to grow and multiply, researchers at Cardiff University said Thursday in a release.

The team calculated the thermal history of comets after they were formed from interstellar and interplanetary dust about 4.5 billion years ago. A supernova injected radioactive material into the Earth's solar system in its infancy and some of the radioactive material became incorporated in the comets, the researchers theorized.

Chandra Wickramasinghe, Janaki Wickramasinghe and Max Wallis said heat emitted from radioactivity warms initially frozen material of comets to produce subsurface oceans that existed for 1 million years.

These calculations, which are more exhaustive than any done before, leave little doubt that a large fraction of the 100 billion comets in our solar system did indeed have liquid interiors in the past, Wickramasinghe said.

Their findings were included in a paper published recently in the International Journal of Astrobiology.