JIRAM Observations of Volcanic Flux on Io: Distribution and Comparison to Tidal Heat Flow Models.

Juno has allowed clear, high‐resolution imaging of Io's polar volcanoes using the Jovian Infrared Auroral Mapper (JIRAM) instrument. We have used data from JIRAM's M‐band (4.78 μm) imager from 11 Juno orbits to construct a global map of volcanic flux. This map provides short‐term insight into the spatial distribution of volcanoes and the ways in which high‐ and low‐latitude volcanoes differ. Using spherical harmonic analysis, we quantitatively compare our volcanic flux map to the surface heat flow distribution expected from models of Io's tidal heat deposition (summarized in de Kleer, Park, et al. (2019, https://doi.org/10.26206/d4wc‐6v82). Our observations confirm previously detected systems of bright volcanoes at high latitudes. Our study finds that both poles are comparably active and that the observed flux distribution is inconsistent with an asthenospheric heating model, although the south pole is viewed too infrequently to establish reliable trends. Plain Language Summary: Our study uses data from an infrared camera on Juno called the Jovian Infrared Auroral Mapper (JIRAM) to image Io, the innermost Galilean moon of Jupiter. Io is the most volcanically active body in the Solar System. Io's volcanoes are powered by both the extreme tides from Jupiter and the gravitational interactions between it and Jupiter's other moons. These tides generate friction inside Io. Simulations of Io's interior suggest that, depending on how deep that friction is being generated, the surface heat flow will be higher in certain areas (de Kleer, Park, et al., 2019, https://doi.org/10.26206/d4wc‐6v82). Using JIRAM, we have mapped where volcanoes are producing the most power and compared that to where we expect higher heat flow from the interior models. Our map doesn't agree with any of these models very well. JIRAM observed more volcanic activity at the poles than we expected to see based on previous observations. However, since the south pole was only observed twice, it's possible that these observations don't represent the average volcanic activity of the south pole. Very bright volcanoes that may have been continuously active for decades were also imaged during these Juno fly‐bys, some of which are nearer the poles than the equator. Key Points: We have produced a global volcanic flux map of Io using data from 11 Juno fly‐bysOur flux map doesn't agree well with tidal heat flow models reported in de Kleer, Park, et al. (2019, https://doi.org/10.26206/d4wc‐6v82)The M‐band flux is anti‐correlated with the asthenospheric heating model and has only very weak agreement with the global magma ocean model [ABSTRACT FROM AUTHOR]