4,- 1Jet Propulsion Laboratory - California Institute of Technology, Planetary Sciences, Pasadena, United States of America (ashley.davies@jpl.nasa.gov)
- 2Lunar and Planetary Laboratory, University of Arizona, 1629 E University Boulevard, Tucson, AZ 85721, USA (jeperry1@arizona.edu)
- 3School of Earth and Space Exploration, Mail Code 6004, Arizona State University, Tempe, AZ 85287, USA (David.Williams@asu.edu)
- 4Department of Astronomy, University of California, Berkeley, CA 94720, USA (imke@berkeley.edu)
- 5Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA (dekleer@caltech.edu)
NASA’s Juno spacecraft has provided vital observations allowing investigation of Io’s extraordinary volcanic activity at global, regional and local scales. Here, we report on volcanic changes on Io since the last Galileo (2002) and New Horizons (2007) flybys as observed by NASA’s Juno spacecraft [1]. We examine Io’s volcanism down to the local scale (<10 km/pixel), drawing upon a catalog of thousands of hot spot detections at (currently) 360 individual locations identified in Jovian Infrared Auroral Mapper (JIRAM) image frames obtained between March 2017 and (at time of writing) August 2024. We describe some of the more prominent areas of volcanic activity first identified or better resolved in Juno data in particular at Tonatiuh, Lei-Kung Fluctus, Volund, Guaraci Fluctus (formerly “East Kanehekili”), Seth Petera [Figure 1], and others, examining appearance, volcanological and geological settings, observed thermal emission, and evolving behavior, quantifying the changes that have taken place. At Tonatiuh we have used JunoCam and Stellar Reference Unit (SRU) data to provide context to the JIRAM infrared observations; at Guaraci Fluctus we combine observations from multiple assets, incorporating data from the James Webb Space Telescope and Keck telescope [2], to provide a more comprehensive understanding of the evolution of this eruption and mapping the newly-emplaced lava flow field [Figure 2]. We note considerable changes in surface appearance at Volund and north of Volund since Galileo. At Vivasvant Patera, located in Io’s north polar region, JunoCam data show a patera floor with multiple, low-albedo, colorful and mostly warm units, with the most prominent, thermally-active area at the base of a steep-sided mountain. We identify changes in the locations of thermal emission at Amirani, showing that lava flow emplacement is now confined to the southern end of the Galileo-era flow field. At Prometheus, JIRAM data show that lava flows are covering new surface areas in the “crook” of the older, Galileo-epoch flow field. This new location of flow emplacement promises to maintain the persistent Prometheus plume through mobilization of surface ices. We further examine different types of active paterae, including activity in the lava lakes at Pele and Loki Patera. We also identify a group of bright eruptions whose spatial and temporal locations might suggest regional clustering, as previously seen in Keck [3] and Galileo NIMS data [4]. Examining the JIRAM dataset from a global perspective, our estimates of volcanic thermal emission are broadly consistent with previous analyses of spacecraft data. Acknowledgements: Part of this work was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract to NASA, and with the support of the New Frontiers Data Analysis Program (award 80NM0018F0612). References: [1] Perry, J. et al. (2025) Plan. Sci. J. 6, 84, doi 10.3847/PSJ/adbae3. [2] de Pater, I. et al. (2025) JGR, submitted. [3] de Kleer, K. and de Pater, I. (2016) Icarus, 280, 378-404, doi 10.1016/j.icarus.2016.06.019 [4] Davies, A. G. and Veeder, G. J. (2023) JGR-Planets, 128, e2023JE007839, doi 10.1029/2023JE007839. [5] Williams, D. A. et al. (2011) Icarus, 214, 91, doi 10.1016/j.icarus.2011.05.007.
Figure 1. (a) The region around Seth Patera (131.1 °W, -4.8 °N) observed by Juno/JIRAM in the M-band filter during orbit 55 (15 October 2023). (b) Composite of six JIRAM frames with pixel scales ranging from 3.7 to 4.5 km. A log stretch was used to accentuate fainter thermal structures, while preserving details within bright areas within the Seth flow field. The composite image is overlain on a Galileo SSI mosaic obtained in July 1999). Thin, filament-like streaks in the JIRAM data are a camera artifact. Figure from [1].
Figure 2. (a) JunoCam imagery of Kanehekili (center left) and Guaraci Fluctus (center right) and surrounding terrain. North is up. JunoCam images are from orbit 58 (3 February 2024). (b) Preliminary updated geological map of Kanehekili Fluctus and Guaraci Fluctus with estimated areas of the low-albedo flow features. Base geologic map is from [5]; units presented here are described therein. The most notable deposits are purple, representing different flow units; cross-hatched regions representing dark diffuse deposits; and slashed areas representing red or orange diffuse deposits. Figure from [1].
How to cite: Davies, A., Perry, J., Williams, D., de Pater, I., de Kleer, K., Seeger, C., and Nelson, D.: Io’s Volcanic Activity: Changes Observed during the Juno Epoch, EPSC-DPS Joint Meeting 2025, Helsinki, Finland, 7–12 Sep 2025, EPSC-DPS2025-372, https://doi.org/10.5194/epsc-dps2025-372, 2025.
