Under Pluto’s icy crust may exist a liquid ocean
One of the most distinctive features of Pluto is its heart. Part of this area known as Sputnik Planitia may be hiding a liquid ocean under a thick, icy crust. An insulating layer of gas hydrates can keep the subsurface ocean from freezing, scientists argue.
In July 2015, NASA’s New Horizons space probe flew near Pluto providing the first detailedołowe images of this distant dwarf planet and its moonow. Photographs have shown the unexpected topography of Pluto, including a white ellipsoidal basin named Sputnik Planitia and roughly the size of Texas, located near ropenetrates.
This region is part of the left lobe of a large, bright structure called the Tombaugh Regio, ktora resembles the shape of a heart – the most distinctive feature of this dwarf planet. Researchers believe that under the left lobe of the „hearts” Pluto’s icy crust may contain a liquid ocean, whichory is protected from freezing by a layer of hydrateoin gas.
The results of the study appeared in the journal „Nature Geoscience”.
The existence of an ocean of liquid water beneath Pluto’s surface is indicated by a number of observations. These are m.In. gravitational anomalies or tectonic features – deep cracks in the area mentioned, whichore appear to come from the process of below-surfaceoin the freezing. The volume of ice is larger than the water that forms it, so cracks form on the surface when it freezes.
Another mechanism to explain the cracks would be gravitational interaction, ktore would have stretched the object and thusob would heat the subsurface ocean. But Pluto does not have a larger object nearby, ktory moheads to produce such an effect, which means that its ocean should freeze.
The issue was pondered by scientists from Hokkaido University, Tokyo Institute of Technology, Tokushima University, Osaka University, Kobe University and the University of California at Santa Cruz. Their heads were busy thinking what could keep the ocean from freezing over. Syndromeoł hypothesized an insulating layer of hydrateoin the gaseous under the icy surface of Sputnik Planitia.
Gas hydrates are ice crystals, in which theoThe gas molecules are trapped in them, the mainownie methane. They are very viscous, have low thermal conductivity and can therefore provide excellent insulating properties.
To support their concept, the researchers conducted computer simulations covering a period of 4.6 billion years, from the beginning of theoin the formation of the Solar System. Simulations showed the thermal and structural evolution of Pluto’s interior and the time it took for the subsurface ocean to freeze over. They simulated two scenarios: one in which theorym there was an insulating hydrate layeroin the gaseous between the ocean and the icy crust, and the other, in which theorym it was not.
Simulations showed that without the insulating layer, the subsurface ocean would freeze completely hundreds of millions ofoin years ago, but with an insulating layer it hardly froze at all. Simulations have shown roalso that it takes about a million years for a dense ice crust to form over the ocean. However, with an insulating layer composed of hydratesoin gas this time stretched to more than a billion years. The results of these studies confirm the possibility of a liquid ocean under the ice crust of the Sputnik Planitia area.
Teamoł believes that the most likely gas in the hypothetical containment layer is methane from Pluto’s rocky core. The concept with methane locked in molecular cages of ice seems to be confirmed by the composition of the atmosphere of the secret dwarf planet, whichora is low in methane and rich in nitrogen.
Similar insulating layers may hold subsurface oceans in other relatively large but minimally heated icy moons and distant celestial bodies. – This could mean that there is more ocean in the Universeoin than previously thought, making the existence of extraterrestrial life more likely – said Shunichi Kamata of Hokkaido University, ktory led a team of researchers.