According to an article in the latest issue of planetary science journal, Icarus, the colossal “ice-scrapers” observed on Pluto’s surface are vestiges from the last Ice Age that occurred on the dwarf planet millions of years ago.
Scientists believe that the “ice blades” are the result of solid methane evaporation that formed the towers of ice on the mountain peaks along Chile’s Chajnantor plain.
"When we realized that bladed terrain consists of tall deposits of methane ice, we asked ourselves why it forms all of these ridges, as opposed to just being big blobs of ice on the ground. It turns out that Pluto undergoes climate variation and sometimes, when Pluto is a little warmer, the methane ice begins to basically 'evaporate'," said Jeffrey Moore, a research scientist at NASA's Ames Research Center in California's Silicon Valley.
Scientists use the term "sublimation" for the process where ice transforms directly into gas, skipping over the intermediate liquid form.
Examining the 3D images sent down by the New Horizons probe, Moore and his colleagues determined that the thin ice blades discovered on Pluto were similar to those found in the Atacama Desert and other mountainous areas in South America, discovered by Charles Darwin back in 1839, and which are created on Earth when the sun’s rays unevenly turn snow drifts into water vapor.
Later, when the climate warmed up, the methane ice started to evaporate forming spiky structures, which over the past several million years have grown to be hundreds of feet tall.
Scientists see this as a sign of Pluto’s climate being much more changeable and dynamic than previously thought.