Pluto May be a Geologically Active Dwarf Planet, New Horizons Reveals

First Posted: Aug 12, 2015 05:18 PM EDT

Pluto may actually be geologically active. Data from NASA New Horizons mission hints that the dwarf planet may be far more "alive" than previously thought.

Pluto's surface and an atmosphere are dominated by nitrogen gas. However, the dwarf planet's small mass allows hundreds of tons of atmospheric nitrogen to escape into space each hour. So how is it that the tiny world still retains nitrogen?

"More nitrogen has to come from somewhere to resupply both the nitrogen ice that is moving around Pluto's surface in seasonal cycles, and the nitrogen that is escaping off the top of the atmosphere as the result of heating by ultraviolet light from the sun," said Kelsi Singer, one of the researchers, in a news release.

In this latest study, the researchers looked at a number of different ways that nitrogen might be resupplied. They wondered if comets could deliver enough nitrogen, or if craters made by comets striking the surface could deliver enough nitrogen. This would, however, require a very deep layer of nitrogen ice at the surface, which isn't proven. The researchers also looked at whether craters could expose more surface area, by punching through surface deposits that would likely be built up over time.

"We found that all of these effects, which are the major ones from cratering, do not seem to supply enough nitrogen to supply the escaping atmosphere over time," said Singer. "While it's possible that the escape rate was not as high in the past as it is now, we think geologic activity is helping out by bringing nitrogen up from Pluto's interior."

Interestingly, the newest images of Pluto show land forms that suggest heat is rising beneath the surface, with troughs of dark matter either collecting, or bubbling up, between flat segments of crust. This could explain how the nitrogen is replenished. With that said, further research is needed before any conclusions are drawn.

The findings are published in The Astrophysical Journal.

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