From Voyager and Galileo to JUICE: Investigating Potential Cryovolcanic Regions on Ganymede

Ganymede, the largest and most massive satellite in the solar system, has been extensively explored by past missions, including Voyager 1 and 2, and, more recently, Galileo. These missions revealed remarkable geological and geophysical features, highlighting the need for further investigation [1;2]. The ESA-led JUpiter ICy moons Explorer (JUICE), launched in April 2023, aims to conduct detailed observations of Ganymede from orbit, with a particular focus on its past and/or recent cryovolcanic and tectonic activity, as well as potential exchanges between the surface, subsurface, and possibly an internal ocean [e.g., 3].Voyager imaging suggested that light material areas on Ganymede might represent resurfaced dark terrain due to cryovolcanic flows [2]. Additionally, small, isolated depressions known as paterae have been proposed as potential cryovolcanic source vents resembling calderas [5]. [6] classified these "potential cryovolcanic regions" as key observation targets for JUICE, incorporating 20 out of 30 previously mapped paterae and other candidate regions identified in Voyager and Galileo data [7]. More recently, JunoCam provided close-up images of Ganymede, revealing previously unrecognized paterae [8]. Their small size suggests localized cryovolcanic activity, making it crucial to investigate whether their formation consistently aligns with tectonic boundaries. The high-resolution imaging capabilities of JUICE's JANUS camera, are expected to resolve long-standing questions about cryovolcanism on Ganymede and the origins of its complex geological features. Here, we present a spectral analysis of high-resolution paterae images captured by Galileo NIMS, along with geomorphological comparisons to analogous features on other planetary bodies. These insights will aid in refining our understanding of cryovolcanic processes and their implications for Ganymede’s evolution and potential habitability.

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