Pluto’s Cryovolcanic Activity Revealed by New Study

A recent study published in *The Planetary Science Journal* has unveiled potential signs of late-stage cryovolcanism on Pluto, particularly within the Kildaze caldera located in the dwarf planet’s Hayabusa Terra region. Researchers aimed to enhance understanding of Pluto’s geological activity, investigating how such phenomena could persist despite the planet’s significant distance from the Sun.

The study utilized images from NASA’s New Horizons spacecraft, which conducted a historic flyby of Pluto in July 2015. By comparing these images with known cryovolcanic sites on Pluto, such as Virgil Fossae and Viking Terra, as well as analog sites on Earth and Mars, the team sought to identify evidence of past cryovolcanic activity. Notable Earth analogs included the Yellowstone caldera, Valles Caldera, and Long Valley Caldera, while Mars was represented by collapsed pit craters in the Noctis Labyrinthus region of Valles Marineris, the largest canyon system in the solar system.

To analyze the Kildaze caldera, researchers employed a range of tools, including digital elevation models, elevation profiles, and 3D visualizations. This approach allowed them to ascertain the origins of the water ice present in the area. The findings indicated that the water ice within Kildaze is likely a few million years old, considerably younger than Pluto itself, yet it still suggests a relatively recent geological history.

The researchers concluded that Kildaze is likely a cryovolcano with a caldera structure, indicating a history of one or more eruptions that may have expelled approximately 1,000 km³ of cryolava, along with smaller eruptions yet to be quantified. Cryovolcanism, as defined by its icy “magma,” contrasts with traditional volcanic activity characterized by hot lava. Since the term was first introduced in 1987, cryovolcanism has been documented on various celestial bodies, including Ceres, Europa, Ganymede, Enceladus, Titan, and several moons of Uranus.

What makes Pluto’s case particularly intriguing is its position as the most distant known planet from the Sun, raising questions about the mechanisms driving its geological activity. Scientists hypothesize that potential sources of Pluto’s internal heat may include tidal heating from interactions with its largest moon, Charon, or radiogenic heating from the decay of isotopes within its interior. A study published in the journal *Icarus* in 2022 proposed that Pluto’s internal heat is primarily a result of tidal interactions with Charon, suggesting that this relationship helps retain heat long after Charon’s own internal heat has dissipated.

Although New Horizons remains the only spacecraft to have visited Pluto, proposals for future missions are underway. Among these is a concept for an orbiter-lander combination powered by a fusion reactor, expected to reach Pluto in just four years, a significant reduction compared to the nine years taken by New Horizons. As scientists continue to analyze the wealth of data returned by New Horizons, further insights into Pluto’s geological activity, particularly its cryovolcanism, are anticipated in the years to come.

The implications of this study are far-reaching, shedding light on the ongoing geological processes at work on Pluto. The findings not only deepen our understanding of this distant world but also contribute to the broader field of planetary science, enhancing our appreciation for the diverse geological phenomena that exist beyond Earth.