Pluto seems frozen in the cold, far beyond Neptune. Yet the images from the New Horizons probe continue to deliver surprises. Researchers have identified the first confirmed landslides on the surface of the dwarf planet.
The discovery does not come from a new mission. It results from a thorough examination of images taken during the 2015 flyby. Even after a single close visit, the data from New Horizons remain rich enough to reveal new landscapes.
Artist's view of the New Horizons probe carrying plutonium.
New Horizons/Wikimedia
The team spotted six debris flows in three craters located near Sputnik Planitia. This vast plain of nitrogen ice forms the famous heart-shaped bright region. The observed traces descend the inner walls of the craters.
These landslides left behind wide sheets of material. Some extend 10 to 14.5 km across the crater floors. The largest would cover about 130 km², an area comparable to that of a small town.
On Earth, such movements are often slowed by friction and gravity. On Pluto, the situation is very different. Low gravity and icy materials could allow debris to travel greater distances more easily.
Map of landslides on Pluto:
(a) general location;
(b-b′) landslide LD1 in Coughlin crater;
(c-c′) landslides LD2 and LD3 in Giclas crater;
(d-d′) landslides LD4, LD5, and LD6 in an unnamed crater.
Images from New Horizons' LORRI camera, resolution of about 300 m per pixel.
Credit: NASA / JHUAPL / SwRI.
The images show hummocky deposits, probably rich in blocks of solid ice. At their starting point, researchers observe well-defined concave cliffs. This set of shapes corresponds to the signatures expected after a landslide.
The exact origin of these movements remains uncertain, however. In one crater, a nearby impact may have destabilized the slope. Elsewhere, temperature variations and state changes of volatile ices may have weakened the terrain.
These observations do not necessarily indicate that Pluto is still sliding today. They nonetheless show that its relief was shaped by complex movements of material. Future, more precise images would help spot other traces on this icy world.