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| A new study led by Southwest Research Institute (SwRI) posits that liquid nitrogen is rising to Pluto’s surface through cracks in the northern edge of the Sputnik Planitia, part of the massive heart-shaped glacier on the dwarf planet’s surface. This is the first evidence of liquid flowing currently on Pluto. For scale, Pluto is about 3/4ths as wide as the continental United States. Image Credit: Courtesy of NASA/Johns Hopkins APL/SwRI |
Scientific Frontline: Extended "At a Glance" Summary: Liquid Nitrogen Flows on Pluto
The Core Concept: Recent analyses indicate that liquid nitrogen is actively or recently rising to the surface of Pluto's Sputnik Planitia, marking the first evidence of recent liquid flows on the dwarf planet. This phenomenon creates distinct surface features comparable to meltwater channels found on Earth's glaciers.
Key Distinction/Mechanism: Because Pluto's atmospheric and thermal conditions make liquid precipitation physically impossible, the liquid nitrogen originates from basal melting beneath the kilometers-deep glacier. Driven by buoyancy and basal pressure, the liquid travels upward through narrow conduits—similar to geysers or lava tubes—where it reaches the surface, flows downward along slopes, and temporarily darkens the surrounding nitrogen ice.
Major Frameworks/Components:
- Geologic Convection Cells: Large, city-sized structures located on the northern Sputnik Planitia that are separated by dark, occasionally wetted linear and diffuse features.
- Basal Melting Dynamics: Computational models demonstrating that stress, strain, and depth-induced pressure at the base of solid nitrogen glaciers can melt the material into a liquid state.
- Comparative Planetary Glaciology: Methodological comparisons between New Horizons data and NASA Landsat 9 imagery of the Greenland ice sheet, linking terrestrial water-melt patterns to plutonian nitrogen-melt patterns.
Branch of Science: Planetary Science, Astrophysics, and Glaciology.
Future Application: These dynamics offer a framework to evaluate similar geyser and cryovolcanic activity across the Kuiper Belt and on outer-planet moons like Neptune's Triton. Furthermore, the findings motivate new laboratory research into the physics of solid-state nitrogen under stress at extremely low temperatures.
Why It Matters: This discovery redefines Pluto as a world with active, time-variable surface geology, demonstrating how complex internal thermodynamics drive material behavior in extreme extraterrestrial environments.
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| Researchers for an SwRI-led study compared New Horizons images to NASA Landsat 9 images of the Greenland ice sheet. Dark, narrow surface features have been identified here in areas in Greenland where liquid water darkens the ice and snow in a manner analogous to what is now believed to perhaps be occurring on northern Sputnik Planitia on Pluto due to present or recent liquid nitrogen there. The newly-published Pluto study identifies very similar features in the northern edge of Pluto’s Sputnik Planitia glacier, suggesting the recent presence of liquid nitrogen there. Image Credit: Courtesy of NASA/Johns Hopkins/SwRI |
A new study led by the Southwest Research Institute (SwRI) provides evidence that liquid nitrogen is rising to Pluto’s surface through cracks in the northern edge of Sputnik Planitia, part of the massive heart-shaped glacier on the dwarf planet’s surface. This is the first evidence of liquid recently flowing on Pluto. The study is based on data from NASA’s New Horizons spacecraft and is led by SwRI associate vice president Dr. Alan Stern, the principal investigator of the New Horizons mission.
“Pluto never stops surprising us,” lead author Stern said, “and this new result certainly does that. In addition to suggesting that liquids have recently expressed themselves on Pluto’s surface, it also suggests a new kind of time-variable feature on Pluto.”
Sputnik Planitia is a vast, frozen nitrogen glacier on Pluto, larger than Texas and Oklahoma combined. In 2015 and 2016, New Horizons images of the northernmost portions of this region revealed city-sized geologic convection cells on Sputnik Planitia, separated by thin, dark, linear features and more diffuse, dark features. New analyses now indicate that these dark, linear, and diffuse features appear to be occasionally wetted by a liquid—most likely liquid nitrogen. This result has been published in the peer-reviewed Planetary Science Journal.
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| Pluto’s northern Sputnik Planitia glacier (in the western or left side of Pluto’s brightheart) is shown here in a color mosaic made from New Horizons imagery. The direction of north is shown on the image. The image is ~ 700 x 350 kilometers across. The red box has been added to show most of the region containing dark features attributed to the wetting of the glacier by liquid nitrogen sourced from a “basil melting” process beneath the glacier, as described in the published paper by Stern et al. (2026) Image Credit: Courtesy of NASA/Johns Hopkins APL/SwRI |
Pluto’s atmospheric and thermal conditions make liquid nitrogen rain physically impossible. Nonetheless, the surface patterns on northern Sputnik Planitia have been darkened in ways that resemble glacial features on Earth that have been wetted by water rain or the emergence of subsurface liquids.
The SwRI-led team of Pluto researchers compared the New Horizons images to NASA Landsat 9 imagery of locations on Earth, including the Greenland Ice Sheet. There, dark, narrow surface features have been identified in areas where liquid water occurs on the ice and snow. The Sputnik Planitia images from New Horizons appear very similar, suggesting that subsurface liquids, specifically nitrogen, are rising and wetting Pluto’s nitrogen ice.
“The surface of Sputnik Planitia is quite young, probably less than 1 million years based on modeling of the surface overturn, and thus these features that we are looking at must have formed since then,” said SwRI principal scientist Dr. Kelsi Singer, one of the study’s co-authors. “Pluto has many unique terrains seen nowhere else in the solar system, and this area of Sputnik Planitia is one of them. Its surface provides a different set of conditions compared to what we are used to on Earth, and exploring that allows us to better understand how materials behave in environments that are difficult to produce on Earth.”
The new work provides the first evidence of recent liquid flows to the surface of Pluto. Earlier research, including some led by first author Stern, suggested ancient liquid flows, but the new work suggests there is currently, or was recently, liquid nitrogen beneath the surface of the glacier.
Computer modeling led by Dr. Orkan Umurhan, senior research scientist at the SETI Institute, shows that nitrogen ice at the base of Pluto’s kilometers-deep Sputnik glacier can melt, forming liquid nitrogen. Furthermore, these computer models revealed that this liquid can be transported upward to the surface through small conduits, similar to lava or geyser tubes, driven by buoyancy or pressure from below. The researchers found that once reaching the surface, the melted nitrogen can remain liquid long enough to flow down slopes on Sputnik Planitia's nitrogen glacier, wetting the icy surface and producing the observed dark features.
“I think the great significance of these findings, and the tantalizing picture that it promotes, is a great motivation and reason to further examine solid-state nitrogen physics at very low temperatures,” Umurhan said. “Specifically, it’s important to examine the physics taking place in solid nitrogen materials under stress and strain, which can cause them to melt. These processes have never been studied in real detail in the laboratory.”
While no other regions of Pluto show evidence of basal flow, over half of Pluto remains unmapped in high resolution. The melting process and the liquid’s upward movement on Pluto could also potentially explain other events seen across the solar system, such as the geysers observed by NASA’s Voyager 2 on Neptune’s moon Triton. Further high-resolution mapping of Pluto and other Kuiper Belt planets is needed to determine if similar processes are occurring elsewhere in that region of the solar system.
additional information: The Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, designed, built, and operates the New Horizons spacecraft and mission for NASA’s Science Mission Directorate. The Planetary Missions Program Office at Marshall Space Flight Center (MSFC) in Huntsville, Alabama, provides NASA oversight for New Horizons. Southwest Research Institute, based in San Antonio, directs the mission via principal investigator Dr. Alan Stern, who leads the science team, payload operations, and science planning. New Horizons is part of the New Frontiers Program managed by NASA's MSFC.
Published in journal: The Planetary Science Journal
Title: Evidence for Possible N2 Basal Flow beneath Pluto’s Northern Sputnik Planitia
Authors: S. A. Stern, Orkan Umurhan, Gary D. Clow, Robert S. Anderson, Alan Howard, and Kelsi N. Singer
Source/Credit: Southwest Research Institute
Edited by: Scientific Frontline
Reference Number: PS080526_01
