Aug. 31 (UPI) -- Scientists at the University of Chicago and Pennsylvania State University believe some water worlds could be habitable.
Scientists have identified oceans on the moons of Jupiter and Saturn as a prime target for the discovery of alien life, but most assumed water worlds -- planets covered entirely by water -- are inherently unstable.
However, new research suggests water worlds are more stable than previously thought.
"This really pushes back against the idea you need an Earth clone -- that is, a planet with some land and a shallow ocean," Edwin Kite, assistant professor of geophysical sciences at Chicago, said in a news release.
Because it takes a long time for life to develop and evolve, scientists searching for alien life look for atmospheric stability. Land is essential to Earth's approach to longterm climate stability.
Across large time scales, Earth cools itself by pulling greenhouse gases from the atmosphere and turning them into minerals, and warms itself by releasing carbon into the atmosphere via volcanoes.
Water worlds can't use the Earth method. To see if there was an alternative approach to atmospheric stability, scientists simulated thousands of randomly generated planets. Their model tracked the evolution of the atmosphere on each simulated world.
"The surprise was that many of them stay stable for more than a billion years, just by luck of the draw," Kite said. "Our best guess is that it's on the order of 10 percent of them."
As their model revealed, some water worlds are born with just the right amount of carbon and are the right distance from their host star. The landless planets simply stabilize their climate by moving carbon back and forth between their oceans and atmosphere.
Kite and his colleagues detailed their work this week in the Astrophysical Journal.