The far-reaches of our solar system is far from boring. NASA’s New Horizons probe proved that. When New Horizons approached the dwarf planet last year, no one knew what to expect. All we had to go on were blurry images captured from the most powerful telescopes.

Most of us assumed we would see an ancient world peppered with craters. A world with no geological activity. We couldn’t be more wrong. We found a world with smooth plains, ice volcanoes and hazy skies.

Pluto haze

Pluto mountains and plains

Hints of a time when liquids flowed and pooled on the surface.

Pluto pond

And a world that is geologically active, with evidence of tectonic activity across Pluto’s icy surface. How? It’s a question planetary scientists have grappled with since the first images were beamed back to Earth.

A trio of scientists have a potential answer – a subsurface liquid water ocean. The team used modeling to explain what drives the geological activity on the planet’s surface.

“Our model shows that recent geological activity on Pluto can be driven just from phase changes in the ice – no tides or exotic materials or unusual processes are required. If Pluto’s most recent tectonic episode is extensional, that means that Pluto may have an ocean at present. This lends support to the idea that oceans may be common among large Kuiper Belt objects, just as they are common among the satellites of the outer planets,” said Amy Barr, co-author of a new paper detailing the results.

Let’s break what they looked at. The one thing that stands out about Pluto’s surface is the lack of compressional tectonic features. These form if the innermost layers of water had frozen into a denser form of ice called ice II. It’s a phase of ice formed under high pressures and low temperatures. A set of conditions we would expect to see in Pluto’s ice shell.

“The formation of ice II would cause Pluto to experience volume contraction and compressional tectonic features to form on the surface,” says lead author Noah Hammond. “Since the tectonic features on Pluto’s surface are all extensional and there is no obvious compressional features, it suggests that ice II has not formed and that therefore, Pluto’s subsurface ocean has likely survived to present day.”

If this model is correct, the implications are huge. Subsurface oceans could be a common feature throughout the Kuiper Belt. And where there is water, there is the potential for life.

Man, it makes you wish New Horizons could have entered orbit around Pluto. Imagine what we could learn with months or years of continuous study instead of a flyby. C’mon NASA, let’s head back to Pluto again.


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