1,2,3,4,6,2,8,9,10,12- 1Hellenic Space Center (HSC), Space Sciences and Space Exploration, Athens, Greece (anezina.solomonidou@hsc.gov.gr)
- 2Université Paris Cité, Institut de Physique du Globe de Paris, CNRS, Paris, France
- 3Institute of Planetary Research, German Aerospace Center (DLR), Berlin, Germany
- 4Istituto Nazionale di Astrofisica – Istituto di Astrofisica e Planetologia Spaziali (INAF-IAPS), Rome, Italy;
- 5Blue Marble Space Institute of Science, Seattle, WA, USA
- 6LIRA, Paris Observatory, Univ. PSL, Sorbonne Univ., Université Paris Cité, CY Cergy Paris Univ., CNRS,92190 Meudon, France
- 7Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
- 8INAF - Astronomical observatory of Padova, Padova, Italy
- 9Università degli Studi Gabriele d'Annunzio, Italy
- 10Department of Geophysics, Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic
- 11SETI Institute, Mountain View, CA, USA
- 12European Space Research and Technology Centre, Netherlands
Ganymede, Jupiter’s largest moon and a confirmed ocean world, is one of the primary targets of the European Space Agency’s European Space Agency JUICE mission, launched in April 2023. A major scientific objective of JUICE is to investigate the geological evolution of Ganymede and assess evidence for past or potentially ongoing cryovolcanic and tectonic activity, as well as material exchange between the surface, subsurface, and internal ocean. Candidate cryovolcanic regions are considered of particular astrobiological interest and have been identified by the JUICE Science Working Team as high-priority observational targets.
Previous studies based on Voyager and Galileo imagery identified approximately twenty candidate paterae and possible cryovolcanic regions on Ganymede (Collins et al., 2013). However, their origin, composition, and geologic context remain poorly constrained due to the limited spatial and spectral resolution of currently available datasets.
Here, we present a comprehensive reassessment of these twenty candidate regions in preparation for upcoming JUICE observations. We combine geomorphological analysis with a systematic compositional investigation using reprocessed Galileo Near-Infrared Mapping Spectrometer (NIMS) data and a consistent linear spectral unmixing methodology. Our approach enables comparative evaluation of spectral variability and compositional trends across all candidate regions using temperature-dependent laboratory spectral endmembers.
The results reveal distinct spectral groups among the candidate paterae, ranging from water-ice-dominated terrains to salt-rich assemblages, with systematic differences observed between model runs under varying thermal conditions. Several regions exhibit coherent morphological and compositional characteristics compatible with cryovolcanic resurfacing and/or brine-related processes. These candidate regions emerge as particularly compelling targets for future high-resolution observations by JUICE instruments, including JANUS and MAJIS.
This work refines the prioritization of candidate cryovolcanic regions on Ganymede and provides an important framework for the interpretation of forthcoming JUICE observations, contributing to the broader investigation of ocean worlds and their astrobiological potential.
How to cite: Solomonidou, A., Ntinos, C., Stephan, K., Tosi, F., Malaska, M., Coustenis, A., Rodriguez, S., Lopes, R., Lucchetti, A., Mitri, G., Kalousova, K., Valenti, M., and Witasse, O.: Identifying Priority Cryovolcanic Targets on Ganymede for ESA’s JUICE Mission, Europlanet Science Congress 2026, The Hague, The Netherlands, 7–11 Sep 2026, EPSC2026-269, https://doi.org/10.5194/epsc2026-269, 2026.
