Researchers Uncover Evidence of Cryovolcanism on Pluto

A recent study published in *The Planetary Science Journal* reveals compelling evidence of cryovolcanism on Pluto, specifically within the Kildaze caldera located in the dwarf planet’s Hayabusa Terra region. Researchers aim to enhance understanding of Pluto’s geological activity, particularly how such processes can occur so far from the Sun.

The team analyzed images collected by NASA’s New Horizons spacecraft, which conducted a historic flyby of Pluto in July 2015. These images were compared with other cryovolcanic sites on Pluto, such as Virgil Fossae and Viking Terra, as well as analogous sites on Earth and Mars. On Earth, researchers looked to the Yellowstone caldera, Valles Caldera, and Long Valley Caldera for comparison, while Martian analogs included collapsed pit craters in Noctis Labyrinthus, a canyon-filled area in Valles Marineris, the largest canyon in the solar system.

To investigate the origins of the water ice found in Kildaze, the researchers employed a combination of digital elevation models, elevation profiles, and three-dimensional visualizations. Their findings suggest that the water ice in Kildaze is likely a few million years old, significantly younger than Pluto itself. The study concluded, “In consideration of the size, structure, composition, and youth of Kildaze and its surroundings, we suggest that this region is a cryovolcano with a caldera structure, having a history of one or more eruptions ejecting 1,000 km³ of cryolava, and possibly an unknown number of eruptions of a smaller scale.”

Cryovolcanism is characterized by the ejection of icy materials instead of molten lava typical of traditional volcanism. Since the term was first introduced in 1987, cryovolcanism has been observed on various celestial bodies including Ceres, Europa, Ganymede, Enceladus, and Titan. Potential mechanisms behind this phenomenon include external processes like impact cratering, tidal heating due to gravitational interactions, or internal heat generated by radioactive decay.

What makes Pluto’s case particularly fascinating is its distance from the Sun, raising questions about the sources of its internal heat. Scientists are divided on whether tidal heating from interactions with its largest moon, Charon, or radiogenic heating is responsible for maintaining Pluto’s geological activity. A study published in *Icarus* in 2022 proposed that tidal heating from Charon might allow Pluto to retain heat long after Charon itself had cooled.

Since the New Horizons mission, which took nearly nine years to reach Pluto, proposals for future missions have emerged. One concept includes an orbiter-lander combination powered by a fusion reactor, with the potential to reach Pluto in just four years. As research continues, scientists remain focused on the data returned by New Horizons, eager to unlock further secrets of Pluto’s geological processes.

As researchers dive deeper into the mysteries of Pluto’s cryovolcanic activity, the scientific community anticipates new revelations in the coming years. Understanding these processes not only sheds light on Pluto but also enriches our knowledge of cryovolcanism across the solar system. The quest for knowledge about our celestial neighbors continues, reminding humanity of the endless wonders that await exploration.