London: Did far-off comets housing vast oceans of water during the first million years of formation harbour some kind of primitive life?
The existence of water in comets bolsters support for a possible connection between life on Earth and comets.
The theory, known as Cometary Panspermia and pioneered by Chandra Wickramasinghe and the late Sir Fred Hoyle, argues that life was introduced to Earth by comets.
"These calculations, which are more exhaustive than any done before, leaves little doubt that a large fraction of the 100 billion comets in our solar system did indeed have liquid interiors in the past," Chandra Wickramasinghe, professor at Cardiff University and study leader, said.
The Cardiff University team has calculated the thermal history of comets after they formed from interstellar and interplanetary dust approximately 4.5 billion years ago.
Wickramasinghe and colleagues claim that the heat emitted from radioactivity warms initially frozen material of comets to produce subsurface oceans that persist in a liquid condition for a million years.
The formation of the solar system itself is thought to have been triggered by shock waves that emanated from the explosion of a nearby supernova.
The supernova injected radioactive material into the primordial solar system and some became incorporated in the comets.
Comets in recent times could also liquefy just below their surfaces as they approach the inner solar system in their orbits. Evidence of recent melting has been discovered in recent pictures of comet Tempel 1 taken by the "Deep Impact" probe in 2005.
These findings were published in the International Journal of Astrobiology.