3,5,- 1Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, USA
- 2Laboratoire de Planétologie et Géosciences, CNRS Nantes Université, Université d’Angers, Le Mans Université, Nantes, France
- 3Department of Earth and Planetary Sciences, Harvard University, Cambridge, USA
- 4Department of Earth and Planetary Sciences, University of California, Riverside, USA
- 5Jet Propulsion Laboratory, California Institute of Technology, Pasadena, USA
Cassini/INMS observations of Saturn’s largest moon Titan, a frigid world T0~ 94 K, hosting a terrestrial-like atmosphere composed predominantly of N2, strongly suggest a missing flux of H2 and CH4 gas in its ~ 1.4 bar atmosphere. Indeed, modeling efforts to date have explored the possibility of extant life on this habitable world, via the process of methanogenesis akin to Enceladus. However, the precise atmospheric influence of cryovolcanism on this likely active body has been understudied, a mechanism Europa Clipper is set to probe at Jupiter’s moon Europa. Here we show that if H2 is sourced from the interior of Titan it is not implausible that it is in thermal equilibrium with its atmosphere. This implies a component of Titan’s atmosphere is indeed sourced by subterranean outgassing and possibly hydrothermal vents, both of which have significant astrobiologic implications. In our surface-atmosphere model, non-equilibrium photochemistry determines the lifetime of the outgassed volatiles, which may in principle, be stochastic. Given that Titan’s high-eccentricity suggests its orbit has undergone significant dynamical evolution, experiencing a range of gravitational tides from ~100 Myr – 4.5 Gyr, it is difficult to determine the current state of Titan’s outgassing without an in-situ Geophysics and Meteorology package, such as the upcoming Dragonfly/DraGMet with a mission launch date set for July 2028. Synthetic Aperture Radar features by Cassini RADAR however do suggest that a putative cryovolcano such as Doom Mons may have fully supplied the hydrocarbon atmosphere against its photodissociation and escape rates over geologically recent timescales. Another putative cryovolcano Erebor Mons, along with geomorphological evidence of equatorial maar-like pits, implies Titan’s volcanic output over time, is far larger than the current venting rate at Enceladus. Although atmospheric hydrocarbon measurements appear to be energetically favorable for possible subterranean life, it is unclear whether the venting hydrocarbons are a product of a subsurface ocean. Future measurements by the Dragonfly Mass Spectrometer (DraMS) will be able to distinguish subsurface end-members under various thermal equilibrium and non-equilibrium chemical conditions.
How to cite: Oza, A., Yung, Y., Tobie, G., Adams, D., Park, J., Schoenfeld, A., Vance, S., Yang, J., Bagheri, A., Bartlett, S., Malaska, M., Petricca, F., Thiagarajan, N., and Lopes, R.: Hydrothermal and Tidal Energy Flux at Titan, Enceladus, and Europa, EPSC-DPS Joint Meeting 2025, Helsinki, Finland, 7–12 Sep 2025, EPSC-DPS2025-1715, https://doi.org/10.5194/epsc-dps2025-1715, 2025.
