Pluto is revealing a surprisingly dynamic side. A new study led by researchers at the Southwest Research Institute (SwRI) suggests that liquid nitrogen may be actively seeping onto the dwarf planet’s surface, marking the first evidence of recent liquid flow on Pluto.
The Discovery
Re-examining high-resolution imagery from NASA’s New Horizons spacecraft, scientists focused on Sputnik Planitia—a massive, heart-shaped glacier larger than Texas and Oklahoma combined.
- Dark Markings: Researchers identified narrow dark lines and diffuse patches across the ice.
- Earth Analogs: These features closely mirror patterns seen on Earth's ice sheets (such as in Greenland) where liquid water sits on top of ice or seeps up from underneath.
- Geologically Young: Because Sputnik Planitia’s surface is estimated to be less than one million years old, these markings likely formed in very recent geological history.
How Nitrogen Liquid Moves on Pluto
Because of Pluto’s freezing temperatures and near-vacuum atmosphere, liquid nitrogen cannot fall as rain. Instead, computer simulations developed at the SETI Institute point to a unique internal process:
- Subsurface Melting: Heat and intense pressure at the base of the multi-kilometer-thick glacier melt the nitrogen ice into a liquid state.
- Rising Conduits: Driven by buoyancy and pressure, the liquid forces its way upward through narrow fractures, acting like subterranean geyser tubes or lava conduits.
- Surface Spreading: Upon breaking through the surface, the liquid nitrogen flows downhill across the icy terrain, wetting the surrounding area and leaving temporary dark tracks before freezing solid.
Why It Matters
These findings challenge the idea of Pluto as a dead, frozen world, proving it harbors time-variable features and active subsurface processes. Furthermore, similar mechanisms could explain mysterious eruptions elsewhere in the outer solar system, such as on Neptune’s moon Triton.
