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FILE – This image made available by NASA in March 2017 shows Pluto lit by the sun as the New Horizons spacecraft moves away from it at a distance of about 200,000 kilometers. Research Institute via AP)
Scientists explain that an ocean on long-frozen Pluto may actually be hidden from view by a cloud of insulating gas.
New research suggests that there could be more oceans in the universe than previously thought and increases the possibilities for extraterrestrial life.
In July 2015, NASA's New Horizons space shuttle flew over the Pluto system and provided the first ever close-up images of the distant dwarf planet and its moons.
After analyzing the images, the scientists estimated that an underwater ocean must exist under an ice shell that was thinning in a Texas-sized basin called Sputnik Planitia.
The team, from the Japanese University of Hokkaido, Tokyo Institute of Technology, Tokushima University, Osaka University, from the University of Kobe and the University of California at Santa Cruz, felt that the ocean should have froze millions of years ago.
But the formation of the lands shown in the images contradicts what was previously thought of the surface, since the inner surface of the ice shell facing the ocean should have appeared flat.
In the new study published in the journal Nature Geoscience, researchers created computer simulations covering a period of 4.6 billion years, when the solar system began to form, to simulate two scenarios.
The simulations showed that without insulating layer of gas hydrates, the ground sea would have froze hundreds of millions of years ago, as it would have been enough for a million years for the ice crust to form completely over the ocean.
But the results suggest that with the insulating layer, the ocean is barely freezing and slowing down the process from a million to a billion years.
The team therefore believes that there must be an "insulating layer" of ice-like crystalline solids formed of gas and trapped in molecular cages below the surface.
Because these gas hydrates are highly viscous and have low thermal conductivity, they could create an insulating effect.
The team believes that the insulating layer is probably made up of methane from the Pluton bedrock, the Pluto atmosphere being low in methane and rich in nitrogen.
Similar insulating layers of gas hydrates could keep other oceans beneath the surface in other icy moons and distant celestial objects, according to the team.
The main author, Associate Professor Shunichi Kamata of Hokkaido University, said: "This could mean that there are more oceans in the universe than previously thought, which would make more plausible the existence of an extraterrestrial life. "
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