A new international scientific study led by Dr. Anezina Solomonidou of the Hellenic Space Center (HSC), with co-author Dr. Athena Coustenis, member of the Board of Directors of HSC, has identified some of the most promising candidate cryovolcanic regions on Ganymede, Jupiter’s largest moon. These regions represent important targets for future observations by the European Space Agency’s Jupiter Icy Moons Explorer (JUICE).

The study, titled “Potential Cryovolcanic Regions on Ganymede: A Priority Target for JUICE”, has been accepted for publication in the Planetary Science Journal and brings together researchers from Greece, France, Italy, Germany, the United States, the Czech Republic, as well as scientists from space organizations including ESA and NASA’s Jet Propulsion Laboratory.

Ganymede is considered one of the most important “ocean worlds” beyond Earth, as a deep subsurface ocean is believed to exist beneath its icy crust. Using reprocessed data from the NIMS spectrometer aboard NASA’s Galileo mission, the research team investigated unusual surface depressions and flow-like structures that may be linked to cryovolcanism — the eruption or emplacement of water-rich and volatile materials instead of molten rock. Among the strongest candidate regions identified are four specific paterae, namely depressions that may have acted as cryovolcanic vents through which icy material reached Ganymede’s surface. Identifying such regions is particularly important for astrobiology, since cryovolcanism may transport material from the subsurface ocean to the surface, providing valuable information about the chemical composition and potential habitability of these icy worlds.

The study also highlights the importance of future observations by JUICE instruments, particularly the MAJIS imaging spectrometer and the JANUS camera system, in determining whether these features are indeed associated with cryovolcanic activity.

Dr. Solomonidou stated:

“Ganymede is one of the most fascinating worlds in the Solar System. Understanding possible cryovolcanic activity can help us better understand how ocean worlds evolve and whether they may host conditions suitable for life.”

The JUICE mission, launched in 2023, is ESA’s first large-class mission dedicated to the exploration of Jupiter’s icy moons and is expected to arrive in the Jovian system in 2031. This study reflects the continuously growing participation of Greek scientists in major international planetary exploration missions and highlights the role of the Hellenic Space Center in ESA’s scientific activities.