Six landslides on Pluto force a rethink of how cold a cold world can be

Six giant landslide deposits, the largest more than 40 kilometres across, have been identified on Pluto from images taken by NASA's New Horizons spacecraft during its 2015 flyby, according to a paper published on 13 July 2026 in the journal Icarus. The find is the first direct evidence of mass wasting on the dwarf planet, and it challenges the long-standing view of Pluto as a static ball of nitrogen and methane ice.

The discovery matters because Pluto has no liquid water, no known sub-surface ocean capable of driving landslides the way Earth's do, and surface temperatures around minus 230 degrees Celsius. Yet the deposits the team mapped, long, lobate flows spilling from scarp edges into surrounding plains, look, in shape and scale, like rock-and-mud slides on Earth or Mars. Something on Pluto is letting ice behave like a granular fluid, even at 40 kelvin.

A familiar shape on an unfamiliar surface

The researchers identified six landslide complexes scattered across Pluto's encounter hemisphere, the face imaged in detail during the 14 July 2015 flyby of New Horizons. Four sit at the eastern edge of Sputnik Planitia, the vast nitrogen-ice plain that forms the western lobe of Pluto's heart-shaped Tombaugh Regio. A fifth lies near the pitted highlands of Piri Planitia, and the sixth on the flanks of an isolated mountain block in the far south of the imaged terrain. The largest deposit extends roughly 44 kilometres from its source scarp; the smallest runs about 10. All show the same morphology: a steep headwall, a debris track, and a broad, tongue-shaped runout at the base.

The deposits are unmistakable in the highest-resolution Long Range Reconnaissance Imager (LORRI) and Multispectral Visible Imaging Camera (MVIC) frames. They were not catalogued in the original post-flyby mapping push, which focused on Pluto's geology at regional scale. They are visible now because the team looked specifically for landforms that, on Earth, are signatures of ice or rock avalanches.

The nitrogen problem

Mass wasting requires a material that can yield under stress and flow. On Earth that role is played by water-saturated soil, snow, or rock; on Mars, by permafrost-rich regolith and CO₂ frost. On Pluto, the obvious candidates are the volatile ices that coat Sputnik Planitia and its surroundings: nitrogen, methane, and carbon monoxide, all of which are mechanically weak compared with water ice and which sublimate rather than melt at Pluto's surface conditions.

The paper, led by planetary scientist Al Emondi and colleagues and published in Icarus, argues that the most likely agent is nitrogen ice, possibly laden with water-ice fragments. Nitrogen is soft enough at Pluto's temperatures to deform under modest stress, and Sputnik Planitia is known to convect on multi-million-year cycles, slowly overturning its nitrogen layer. That convection, combined with sublimation-driven retreat of the plain's margins, could destabilise the edges and trigger failure. Methane and CO₂ frosts layered on top may act as a seasonal trigger, weakening the substrate when they sublimate away each Pluto year of 248 Earth years.

The counter-narrative is that these features are not landslides at all but ancient debris flows from the late heavy bombardment era, frozen in place for billions of years. The paper concedes that older surfaces cannot be ruled out for some of the deposits but notes that several show crisp margins and a lack of superimposed craters, which is consistent with relative youth. Without impact-crater counts on the runouts themselves, the age remains poorly constrained. The argument is geological inference, not chronology.

What it changes

Until now, Pluto's surface has been treated as a slow-motion canvas, shaped by volatile transport and glacial flow on million-year timescales. Landslides add an episodic, catastrophic mode to that repertoire. The implication is that even at 40 kelvin, with no liquid water and an atmosphere measured in microbars, Pluto's surface can change abruptly. That has consequences for how mission planners model hazard and stability around potential future landing sites, including the proposed NASA Persephone concept, a nuclear-powered orbiter and probe that has been in pre-formulation at the Applied Physics Laboratory since 2024.

It also feeds back into comparative planetology. Mars has dry-rock and CO₂-driven avalanches; icy moons such as Europa and Enceladus show chaotic terrains that may involve partial resurfacing by soft ice; Earth has the full water cycle. Pluto now sits inside that continuum rather than outside it. A dwarf planet 40 times farther from the Sun than Earth is running a version of the same geomorphic playbook.

What to watch next

Two follow-ups are realistic on a near-term horizon. First, the team plans higher-order modelling of nitrogen-ice rheology under Pluto conditions, to test whether the runout distances match what a sublimating nitrogen slab can produce. Second, the New Horizons data set remains only partially exploited: the spacecraft returned roughly 50 gigabits of imaging and composition data, and Icarus editors expect more Pluto surface papers through 2027 as the archive is re-mined with new questions in mind.

The honest caveat: with one flyby and no return mission, every Pluto discovery is built on a single snapshot. The landslides are real in the imagery. Whether any of them are still moving, or whether they finished their work in the deep past, the data cannot yet say.

Desk note: Monexus framed this as a planetary-science finding with cross-cutting implications for icy-body geomorphology, rather than as a space-exploration spectacle. The wire ledes emphasised "landslides on Pluto"; the structural question is what nitrogen-ice failure tells us about resurfacing across the outer solar system.

Wire provenance

This editorial synthesis draws on the following public wire/social posts:

• https://www.nasa.gov/mission/new-horizons/
• https://science.nasa.gov/mission/lorri/