A new NASA study has suggested that there could be a high number of icy worlds in the Solar System that has liquid water below the surface.
The findings expand the number of worlds where alien life can be possibly found since liquid water is essential to supporting known form of life. Astronomers think that there are dozens of these potentially habitable worlds.
Trans-Neptunian Objects
Bodies called the Trans-Neptunian Objects, or TNOs, which include the dwarf planet Pluto, lie beyond the orbit of Neptune. These worlds are relatively very far from the sun that their surface temperatures of about 200 degrees Celsius below zero are cold enough to prevent liquid water to exist.
In the new study, however, Prabal Saxena of NASA's Goddard Space Flight Center in Greenbelt, Maryland, and colleagues found evidence that the gravitational interaction of these TNOs with their moons may produce enough heat in the interior of these bodies to sustain liquid oceans beneath their icy surface.
How Liquid Subsurface Oceans Form In Frigid Worlds
Astronomers think that liquid water may exist in Pluto and other outer solar system bodies because analysis of light reflected from some TNOs revealed signatures of ammonia hydrates and crystalline water ice. Researchers suggest that these emerged to the surface from an interior liquid water source through a process known as cryovolcanism.
Most of the long-lived heat inside of TNOs were from the decay of radioactive elements that were infused into these objects. The heat is warm enough to melt a layer of the icy crust and generate a subsurface ocean that can last for billions of years. As the radioactive elements decay into more stable ones, however, they stop releasing heat and this can eventually cool down the interior of these bodies causing any subsurface ocean to freeze.
Implications In The Search For Alien Life
If the findings of the study, which was published in Icarus on Nov. 24, are right, these could have implications in the search for potentially habitable worlds beyond Earth. The presence of water has long been associated with potentials for supporting life.
In an earlier study revealing the likely composition of habitable planets, researchers suggested that even in worlds outside the solar system, the most habitable planets are highly likely waterworlds with oceans.
"These objects need to be considered as potential reservoirs of water and life. If our study is correct, we now may have more places in our solar system that possess some of the critical elements for extraterrestrial life," Saxena said.
