Thermal characteristics of active lava flows on Io observed by the JIRAM instrument on Juno

We use data from the Jovian InfraRed Auroral Mapper (JIRAM) instrument on the Juno spacecraft, acquired during close fly-bys of Jupiter’s moon Io between 2022 to 2024, to identify new characteristics of active lava flows on the surface. At least two new vents as well as a new flow field are identified along with some significant changes seen at other sites. Following on from the Voyager and Galileo missions, the lavas from Amirani and Prometheus volcanoes continue to be active suggesting a long duration (>45 years) for these eruptions. The activity at Amirani has changed since observed by Galileo, with the northern (distal) part of the flow no longer active or below the detection limit of JIRAM at a spatial resolution of 1-10 km/pixel. The flow now displays multiple points of activity visible in the southern flow region and within the dark patera and fracture south of the flow, clearly seen in JIRAM’s higher resolution images. The activity at Prometheus did not show the major changes comparable to those observed between Voyager and Galileo, when the flow and plume moved ~90 km west. However, the hottest area of the flow has shifted to the region around and to the south of the source patera at the eastern end of the 100 km flow field, in the location of the main flow region observed during Voyager. A large (~130 x 40 km) active flow field was detected to the NE of Seth Patera as well as a probable new ~120 km long active flow at a previously unrecognized site designated “Unknown 13”. The spatial distribution of hotspots on each of the observed flows is consistent with the earlier suggestions that the flows are inflated pāhoehoe-type flow fields.