Pluto’s mysterious far side may conceal towering ice formations, according to recent research that offers clues about the bladed terrain marking the dwarf planet’s alien landscape.
These massive ice spires, first spotted by NASA’s New Horizons mission nearly a decade ago, comprise what planetary scientists call a “bladed terrain,” where jagged ridges are formed over time by the erosion of methane ice.
High-resolution images of the Kuiper belt object were initially obtained in 2015 as NASA’s New Horizons spacecraft conducted its flyby of the former planet. Now, analysis of lower-resolution data is adding an additional layer of data that offers clues about the potential presence of similar features on Pluto’s unexplored regions, hinting at climate processes that sculpt Pluto’s entire surface.
The research, by Ishan Mishra and colleagues with NASA’s Jet Propulsion Laboratory (JPL), the California Institute of Technology (Caltech), and international contributors, was published last month in the Journal of Geophysical Research: Planets.
Probing the Unseen with Light
Without any close-up images of Pluto’s far side available, researchers leveraged photometric analysis to test the hypothesis that similar features detected on the dwarf planet’s encounter hemisphere—the probe-facing side photographed by New Horizons in 2015—also appeared on its non-encounter regions.
To achieve this, the international team behind the study examined the way sunlight reflects off different areas on Pluto’s surface, which allowed them to estimate the “macroscopic roughness” of various regions. In essence, this involves how bumpy or jagged the terrain is in relation to what existing imagery can reveal.
The team’s study focused on high-altitude zones in Pluto’s non-encounter hemisphere, where the methane is present in abundance. These regions were areas where the New Horizons spectrometer LEISA had previously detected strong signatures of methane ice.
Employing a “crater-roughness” model originally developed several decades ago, the research team estimated surface roughness on Pluto’s surface by employing models that examined the way light bounces off parabolic depressions—one could think of these as areas featuring bowl-shaped craters.
Although there was a fair amount of uncertainty about the exact values, the team nonetheless produced clear results that reveal regions on Pluto hypothesized to feature bladed terrain were significantly rougher than other areas of Pluto, including the known bladed terrain on its encounter hemisphere, as seen during the New Horizons flyby several years ago.
Spiky Clues to an Active World
The new research contributes to the growing body of data that suggests bladed terrain on icy planets such as Pluto forms through sublimation, where methane ice transforms directly from a solid to a gas. This would account for the formation of bowl-like depressions with razor-edged ridges extending several hundred meters in height.
The process is likely driven by long-term climate cycles and variations in solar heating. The fact that Pluto’s far side may also host these features suggests that sublimation-driven erosion is a global phenomenon on the dwarf planet, occurring across its hemispheres over long stretches of geological time.
Expanding the Map of Pluto
Since Pluto’s encounter hemisphere received most of the attention during the 2015 flyby carried out by New Horizons, there is still limited imagery and other data available about its far side.
Mishra and his team’s recent research, with the clever use of photometry, now offers some of the strongest evidence yet that such geological features are present in areas that currently remain hidden from view.
Additionally, the team’s new study also demonstrates how light-scattering models can aid astronomers in studying other distant planetary surfaces for which imagery is currently lacking. The technique may even prove invaluable for future planetary missions, where high-resolution imaging may not be possible due to shadows cast by large crater rims or other features that conceal portions of the surface.
The new findings were detailed in the paper, “Investigating the Extent of Bladed Terrain on Pluto via Photometric Surface Roughness,” published on July 5, 2025.
Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. He can be reached by email at micah@thedebrief.org. Follow his work at micahhanks.com and on X: @MicahHanks.