CRYOVOLCANISM ON TITAN AND ELSEWHERE IN THE SOLAR SYSTEM

Volcanism is a fundamental geologic process in the solar system, as it has occurred on most solid planetary bodies. Planetary volcanism is manifest across a range of morphologies, driving conditions, and compositions, including ices. Volcanism that occurs on the outer solar system’s satellites, known as cryovolcanism, is primarily the eruption of aqueous or non-polar molecular solutions or partly crystallized slurries, derived from partial melting of ice-bearing materials. Observations of Neptune’s moon Triton by the Voyager 2 spacecraft in 1989 revealed plume streaks and smooth surface regions interpreted as cryovolcanic. Jupiter’s moons Europa and Ganymede also show evidence of cryovolcanism, including the possible detection of active plumes. More recently, cryovolcanic features have been identified on Pluto by the New Horizons mission and on Ceres by Dawn, providing further evidence of the importance of cryovolcanism in shaping planetary surfaces.

The Cassini mission to Saturn has significantly added to our knowledge of cryovolcanism, revealing active jets from Enceladus that bring material from the interior ocean. Cryovolcanism likely also occurred on Titan, a world that Cassini data have revealed to be complex, in which interior, surface and atmospheric processes interact to create and modify geologic features. In terms of active or recent surface-shaping processes, Titan is one of the most Earthlike worlds in the Solar System. The most likely cryovolcanic features on Titan are in the Sotra Patera region, which a combination of data sets has shown to include the deepest pit known on Titan (Sotra Patera) and some of the highest mountains (Doom and Erebor Montes). Cryovolcanism on Titan can explain outgassing over time to sustain the methane in the atmosphere and has important implications for the satellite’s astrobiological potential. This paper will discuss evidence for and against cryovolcanism on Titan which, even at the end of the Cassini mission, is still a controversial topic.