Pluto's ice volcanoes are very strange

Pluto’s ice volcanoes are very strange

Perspective view of the icy volcanic region of Pluto

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

Images collected by NASA’s New Horizons spacecraft in 2015 hinted at the presence of ice volcanoes on Pluto. New analysis of the data suggests they are in fact a prominent feature of the dwarf planet, with the largest reaching over 4 miles (6.4 km) tall.

Ice volcanoes are similar to “normal” volcanoes, except that they eject icy material instead of lava. They are known to exist throughout the solar system, including on Saturn’s moon Enceladus and the dwarf planet Ceres, with data from New Horizons suggesting they are even found on distant Pluto. A new research published today in Nature Communications claims that ice volcanoes exist to a large extent on the dwarf planet, and to a degree never thought possible.

“We suspected that some features of Pluto were icy volcanoes, but now we’ve determined that there are a lot of them and they cover a very large area,” said Kelsi Singer, first author of the new study and planetary scientist. in Southwest. Research Institute in Boulder, Colorado, explained in an email. “It requires a large volume of moving icy material, and it requires more heat than we originally thought would be available near Pluto’s surface.”

The old adage says that where there is smoke, there is fire, but in this case where there are cryovolcanoes, there must be liquid water. And for liquid water to exist, there must be heat. Preliminary research has suggested that there is virtually no heat beneath Pluto’s surface, but new findings are now challenging that assumption. Singer and his colleagues aren’t sure exactly how Pluto managed to retain so much heat, “but one idea is that there is an insulating layer on Pluto or parts of Pluto that can trap heat, and heat can s “Build up to low levels.” Higher over time,” Singer said.

A colorized view of Wright Mons in the cryovolcanic region

A colorized view of Wright Mons in the cryovolcanic region
Picture: NASA/JHUAPL/SwRI

The largest of the observed features is called Wright Mons, rivaling Hawaii’s Mauna Loa in size. Geoffrey Collins, professor of geology in the Department of Physics and Astronomy at Wheaton College, likes the new paper but said he is not yet ready to declare it a cryovolcano.

“I’ve seen a lot of weird things on the surface of other worlds, but Wright Mons on Pluto is definitely one of the weirdest,” Collins told me in an email. “This study interprets it as a volcano, but perhaps we need to let go of some of our terrestrial notions of what volcanoes look like when we talk about ice volcanoes on Pluto.”

For the new study, Singer’s team reviewed all available data collected by the New Horizons spacecraft, which flew past Pluto on July 14, 2015 at speeds reaching 84,000 km/h. The team “wanted to collect as much information as possible about these structures, including their sizes and shapes, as well as their composition, to try to understand how they formed,” Singer said.

The scientists focused on an area southwest of Sputnik Planitia, a 1,050 km wide ice-covered impact basin. This is where Wright Mons is located, as well as another important mound known as Piccard Mons, the first named after Orville and Wilbur Wright and the second after Auguste Piccard, a 20th century physicist and balloonist . These and other features in this area were produced by cryovolcanism and consist mostly of water ice, according to the research.

These mounds are impressively large, especially considering that Pluto is only 2,380 km across. The tallest of the volcanic domes is 7 kilometers high and ranges in size from 30 to 100 km wide. As the document notes, this terrain is likely the result of multiple eruption sites and significant amounts of eruptive material.

Singer said she was surprised by the size of the area covered by cryovolcanic material, an expanse measuring 300 km by 600 km, at least as far as they could see. It’s possible that more cryovolcanic material exists in areas that New Horizons missed when it zoomed past. He was also surprised by the complexity of the features.

“There were probably many eruption sites and some of the growing volcanic domes merged,” he said. “It was a challenge trying to figure out how these structures formed, because they are so different from any other structure we’ve seen anywhere in the solar system. But it was also a fun and interesting puzzle to start with the basic information about the features and try to imagine and understand how they formed.

The team experimented with models of various geological processes to see if they could replicate the icy volcanoes seen on Pluto. “The closest model was where material is extruded under volcanoes and they build a dome by injecting material from below,” Singer explained. “But many other models we’ve tried haven’t worked, and there’s still a lot to explain.”

Interestingly, impact craters are not found in this area, unlike other places on Pluto. This suggests that cryovolcanic activity must have occurred relatively recently and that Pluto’s internal structure retains significant amounts of waste heat.

Collins said Wright Mons looks vaguely like a cone with a hole in the middle, but on closer inspection, its slopes don’t appear to be composed of flow from vents, as is the case with terrestrial volcanoes.

“Instead, it’s a crazy quilt of little domes stacked on top of each other, and those are covered by even more bumps and pits,” he told me. “It’s like looking at a head of cauliflower, although this observation gives us no idea what caused it. This hole in the middle is huge, suspiciously reaching to the lower elevation of the surrounding terrain. There is no indication that it has collapsed again, like a volcanic caldera. It’s as if the construction of the volcano prevented half of it for some reason.”

Ultimately, Collins said we still don’t really know what these features are and whether Wright Mons is really a volcano. “I don’t know yet,” he said, “but this paper has a lot of good data and has the best insight yet.”

The best thing about Pluto is that it didn’t disappoint. The dwarf planet has escaped close inspection for so long, forcing us to imagine what it would actually look like. New Horizons has exposed Pluto as the oddball we’ve all been hoping for, an object of curiosity that will keep scientists busy for quite some time.

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