The underground ocean that produced some of the stunning features on Pluto’s surface may still be splashing around beneath the crust today.
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When NASA’s New Horizons spacecraft flew by the tiny world in July 2015, it captured the sharpest-ever images of the planet’s surface.
To determine whether the ocean is still liquid or whether it has already frozen entirely, Hammond and his team ran a thermal evolution model using New Horizons data on Pluto’s diameter and density. This means that if the ocean was now frozen, the pressures at that depth could convert the ice into an exotic form called ice II.
The latest findings suggest the ocean could still hold liquid water beneath its surface, raising hopes that signs of life could still be possible.
Researchers however said that no signs of a global contraction were found on the surface of Pluto.
Long grooves on the surface of Pluto indicated a period of expansion for the dwarf planet.
Researchers were surprised after a detailed study on the geographical details gleaned from New Horizons and discovered that the flowing ice and epic ice mountains standing as high as 3,500 metres.
With the help of computer simulations, the group of Brown University researchers has demonstrated that in case solidification of global liquid ocean has taken place, the heavy outer ice shell would have smashed the freezing ocean into an odd kind of ice known as ice-II. As there is no evidence that has happened, Hammond said that “it suggests that ice II has not formed and that therefore, Pluto’s subsurface ocean has likely survived to present day”. Pluto has complex geology, sporting a surprisingly young surface composed of a rich assortment of chemicals, including water, ammonia and methane ices.
Taken together, the New Horizons data and Brown thermal model suggest Pluto does indeed host a subsurface ocean.
But how do we know it’s still liquid today? The new discovery has been largely attributed to the incredible images from New Horizons, which were recently released in full.
Studies show that even a small amount of such material (including uranium, thorium, and potassium) could produce enough heat inside Pluto to melt some of the water ice.
Noah Hammond, a Ph.D candidate in Brown University’s Department of Earth, Environmental and Planetary Sciences, and the study’s lead author, credits New Horizons for the findings. Tiny, frigid Pluto, long thought to be a frozen ball of ice, may yet have some spring in its step. That form of ice, Ice II, has a dense crystalline structure, and can only form if the planet’s outer shell is at least 260 meters thick.
Researchers had believed that Pluto’s ice shell was 260 kilometers thick, but the findings have made them reconsider the distance to more than 300 kilometers before penetrating the core to where the ocean is believed to have once been or where it can now be found.
“Those exotic ices are actually good insulators”. It was then found that Pluto was much more than a simple snowball in space.
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“That’s wonderful to me”, Hammond concluded. The possibility that you could have vast liquid water ocean habitats so far from the sun as Pluto – and that the same could also be possible on other Kuiper belt objects as well – is absolutely incredible.
