Strange bumpy terrain on Pluto, unlike anything seen before in the solar system, indicates that giant ice volcanoes have been active relatively recently on the dwarf planet, say scientists.

The observation, which was made by analyzing images taken by NASA’s New Horizons spacecraft, suggests Pluto’s interior was warmer much later than previously thought, according to a new published study. in the journal Nature Communications.

Rather than spewing lava into the air, ice volcanoes ooze a “thicker, viscous mixture of ice and water, or maybe even solid flow like glaciers,” said author Kelsi Singer. and planetary scientist at the Southwest Research Institute in Colorado.

Ice volcanoes were already thought to exist on several cold moons in the solar system, but those on Pluto “look so different from anything we’ve ever seen”, Ms Singer told AFP.

“The features of Pluto are the only large field of very large icy volcanoes and they have a unique texture of undulating terrain.”

Singer said it’s hard to determine exactly when the ice volcanoes formed “but we think they could be as young as a few hundred million years old or even younger.”

Unlike much of Pluto, the region has no impact craters, meaning “it cannot be ruled out that it is still forming even today,” he said. she adds.

extremely significant

Lynnae Quick, a planetary scientist at NASA’s Goddard Space Flight Center who specializes in ice volcanoes, said the findings were “extremely significant”.

Perspective view of the icy volcanic region of Pluto. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Isaac Herrera/Kelsi Singer

“They suggest that a small body like Pluto, which should have lost much of its internal heat a long time ago, may have retained enough energy to facilitate widespread geologic activity quite late in its history,” he said. she told AFP.

“These discoveries will lead us to reassess the possibilities of maintaining liquid water on small frozen worlds far from the Sun”.

David Rothery, professor of planetary geosciences at the Open University, said “we don’t know what could provide the heat needed to cause these icy volcanoes to erupt.”

According to the study, one of the structures, Wright Mons, is about five kilometers high and 150 kilometers wide, and has about the same volume as one of Earth’s largest volcanoes, Mauna Loa. in Hawaii.

Mr Rothery told AFP that he had been to Mauna Loa and had “felt the immensity of this volcano”.

“It makes me realize how big Wright Mons is compared to Pluto, which is a much smaller world than ours.”

The analyzed images were taken when the New Horizons – an unmanned nuclear-powered spacecraft the size of a baby grand piano – became the first spacecraft to pass near Pluto in 2015.

They have made it possible to better understand Pluto, which was long considered the furthest planet from the Sun before being reclassified as a dwarf planet in 2006.

“I like the idea that we have so much left to learn about the solar system,” Singer said.

“Every time we go somewhere new, we find new things we didn’t expect, like giant, newly formed ice volcanoes on Pluto. »

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