The dwarf planet Pluto is so small and so far from the Sun that we once thought it was completely frozen. However, the complex geology observed by NASA’s New Horizons spacecraft and analyzed by scientists , coupled with the absence of impact craters in some parts of this world, indicates that recent geologic activity has reshaped some areas.
New topographic data and images
Thanks to new images from New Horizons, scientists have discovered that Pluto’s landscape is sculpted by huge cryovolcanoes that we have never seen anywhere in the solar system. While we have found ice volcanoes elsewhere, such as on the dwarf planet Ceres or on Saturn’s moon Titan, none are quite the shape and type of those on Pluto. One of its colossal ice volcanoes is as large as Hawaii’s Mauna Loa volcano , one of the largest on Earth.
Pluto retains heat better than previously thought
Thus, southwest of Sputnik Planitia, so much sleet has erupted from below the surface that mountains of ice rise up to 7 kilometers high. The Sputnik Planitia Ice Sheet covers an ancient impact basin that is about 1,000 km wide and has high elevations with jagged flanks . Their analysis of the images indicates that the area is likely to be covered in ice volcanoes and that they are mostly made up of water ice.
“One of the regions with very few impact craters is dominated by huge ridges with mountainous flanks. Similar features exist nowhere else in the Solar System imaged,” write researchers from the Southwest Research Institute in Boulder, Colorado. “The existence of these massive features suggests that Pluto’s interior structure and evolution allow for greater heat retention or more heat overall than was anticipated before New Horizons.”
Pluto’s ice volcanoes range in height from a few kilometers to 7 km high and are between 10 km and 150 km wide , with some coalescing to form even larger structures, the authors say in their study published in the journal Nature Communications.
The researchers suggest that several eruptions are likely to have occurred in the past, although a specific timeline remains unclear, but creating the terrain would have required multiple eruption sites and a large volume of material to create these ice volcanoes. .
Although much of Pluto’s surface is riddled with impact craters, the area with the ice volcanoes appears to be impact-free. This suggests that the cryovolcanic activity was “relatively recent,” according to the researchers. It may also indicate that Pluto’s internal structure has more heat than previously thought to drive this cryovolcanic activity.
“The existence of these massive features suggests that Pluto’s interior structure and evolution allow for greater heat retention or more heat overall than was anticipated before New Horizons, allowing for the mobilization of water ice-rich materials.” at the end of Pluto’s history”, clarifies Kelsi Singer, leader of the work.
And how does a cryovolcano or ice volcano act?
Ice volcanoes, rather than hot molten lava, erupt with a “thicker, muddier mixture of frozen water or even possibly a solid flow like glaciers,” says Singer. And it is that it is difficult to think that it was something liquid, because it is too cold in this tiny world: the average temperature of the surface of Pluto is approximately -233 ºC .
Referencia: Singer, K.N., White, O.L., Schmitt, B. et al. Large-scale cryovolcanic resurfacing on Pluto. Nature Communications 13, 1542 (2022). DOI: https://doi.org/10.1038/s41467-022-29056-3