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Posted on May 21, 2019
New simulations of Pluto suggest the possibility of a long-lived liquid ocean existing under the ice crust of Sputnik Planitia located near the equator and about the size of Texas. The simulations showed that without an insulating layer of gas hydrate, the groundwater would have completely froze hundreds of millions of years ago. but with one, he hardly freezes. In addition, it takes about a million years for an ice crust of uniform thickness to form completely over the ocean, but with an insulating layer of ice. Hydrates gas, it takes more than a billion years.
An insulating gas layer beneath the icy surfaces of distant celestial objects could mean that there are more oceans in the universe than previously thought.
Researchers from the Japanese University of Hokkaido, the Tokyo Institute of Technology, Tokushima University, Osaka University and the University of Tokyo. University of Kobe, as well as the University of California at Santa Cruz, have been examining what could maintain the warmth of the ocean underwater while maintaining the internal surface of the frozen and uneven hull. Pluto. The team has speculated that an "insulating layer" of gas hydrates exists beneath the icy Sputnik Planitia surface.
The Pluto view is illustrated above with the color-coded topography as measured by NASA's New Horizons satellite. Purple and blue are low and yellow and red are high, and the unofficially named Planitia Sputnik stands at the top like a large elliptical basin 1300 km (800 miles) wide, 2.5 km (1.5 mile) deep, probably the site of an ancient impact on Pluto. New Horizons data suggest that at the bottom of this nitrogen-filled basin is an ocean of dense, salty, ammonia-rich waters. (MP Schenk LPI / JHUAPL / SwRI / NASA).
The international team estimates that the most likely gas in the assumed insulating layer is methane from the Pluto core. This theory, in which methane is trapped as a gas hydrate, is compatible with the unusual composition of Pluto's atmosphere: low in methane and high in nitrogen.
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Similar insulating layers of gas hydrates could maintain long-lived underground oceans in other relatively large but poorly heated icy moons, as well as in distant celestial objects, the researchers conclude. "It could mean that there are more oceans in the universe than previously thought, which would make the existence of an extraterrestrial life more plausible." "said Shunichi Kamata of the University of Hokkaido, who led the team.
According to a study published in the journal Nature Geoscience, computer simulations convincingly prove that an insulating layer of gas hydrates could prevent an underwater ocean from freezing under the frozen exterior of Pluto.
In July 2015, NASA's New Horizons spacecraft flew over Pluto's system, providing the very first close-up images of this distant dwarf planet and its moons. The images showed the unexpected topography of Pluto, including a white ellipsoidal basin called Sputnik Planitia.
Scientists believe that because of its location and topography, an underwater ocean exists under the ice shell that is cleared at Sputnik Planitia. However, these observations are at odds with the age of the dwarf planet, since the ocean should have been frozen long ago and the inner surface of the ice shell facing the ocean would have also had to be flattened.
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Gas hydrates are ice-like crystalline solids formed from a gas trapped in molecular cages. They are very viscous, have low thermal conductivity and could therefore provide insulating properties.
The researchers carried out computer simulations covering a period of 4.6 billion years, when the solar system began to form. The simulations showed the thermal and structural evolution of Pluto's interior and the time required for the basement ocean to freeze and the ice cover covering it to be uniform in thickness. They simulated two scenarios: one in which an insulating layer of gas hydrates existed between the ocean and the ice shell and the other in which it was otherwise.
The Daily Galaxy via Hokkaido University
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