Thermal Characteristics of Active Lava Flows on Io Observed by the JIRAM Instrument on Juno

Abstract 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 during 2022–2024, to identify new characteristics of active lava flows and changes since observations from previous missions (Voyager, Galileo, and New Horizons). At least two new vents as well as a new flow field are identified along with some significant changes seen at other sites. Our new JIRAM observations of Culann, Tvashtar, Daedalus, Kanehekili, Masubi, Amirani, Prometheus, and Girru show that volcanism continues at these sites since previous missions, in some cases suggesting long duration (>45 years) eruptions. A large (∼130 × 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.” Flows were also detected by JIRAM at Quzah, Xihe, and a large, recently emplaced flow was observed in the south polar region at Illyrikon Regio. Comparison with locations of plumes detected by Juno's camera shows that plumes coincide with distal margins of flow fields where brightness temperatures are high, indicating Promethean‐type flow and plume activity. The spatial distribution of hotspots on most of the observed flows is consistent with earlier suggestions that the flows are inflated pāhoehoe‐type flow fields, although activity at Kanehekili and Quzah Flucti may well display characteristics of higher‐discharge rate, ‘a‘ā, eruptions.