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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 um) imager from eleven 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 et al. 2019). 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., Comment: 11 pages, 3 figures

A new global geologic map of Jupiter's volcanic moon, Io is being prepared, with the focus being on completion of a draft map by July 2008. Here initial results of the mapping are reported: a preliminary distribution of material units in terms of areas and a visual representation. Additionally, the mapping hopes to address some of the problems in Io geology. Thus far it has been discovered that Io's surface is dominated by plains material, thought to consist of Io's silicate crust covered by pyroclastic deposits and lava flows of silicate and sulfur-bearing composition. Many plains areas contain flow fields that cannot be mapped separately due to a lack of resolution or modification by alteration processes. Discrete lava flows and flow fields are the next most abundant unit, with bright (sulfur?) flows in greater abundance than dark (silicate?) flows. The source of most of Io's heat flow, the paterae, are the least abundant unit in terms of areal extent.Upon completion of the draft map for peer review, it will be used to investigate several specific questions about the geological evolution of Io that previously could not be well addressed, including: comparison of the areas versus the heights of Ionian mountains to assess their stability and evolution; correlation and comparison of Galileo Near-Infrared Mapping Spectrometer and Photopolarimeter-Radiometer hot spot locations with the mapped location of dark versus bright lava flows and patera floors to assess any variations in the types of sources for Io's active volcanism; and the creation of a global inventory of the areal coverage of dark and bright laval flows to assess the relative importance of sulfur versus silicate volcanism in resurfacing Io, and to assess whether there are regional concentrations of either style of volcanism that may have implications on interior processes.

Cassini has identified a geologically active province a the south pole of Saturn's moon Enceladus. The shape of Enceladus suggests a possible intense heating epoch in the past by capture into a 1:4 secondary spin/orbit resonance.

Inspired by the finding of Schubert et al that Io's figure is consistent with a hydrostatic shape, we explore the consequences of modeling Loki Patera as the surface of a large magma sea. This model is attractive because of its sheer simplicity and its usefulness in interpreting and predicting observations. Here, we report on that work.

The Galileo Photopolarimeter-Radiometer (PPR), when used in the radiometry mode which is most often used at Io, is a long-wavelength infrared single-aperture photometer. It is sensitive to temperatures from about 60 to several hundred K, and is thus useful for studying the volcanoes and background temperatures on Io. PPR can take raster scan images when it is the primary instrument being used (these data were discussed last year, see Rathbun et al., 2002). It can also take data in ride-along mode in conjunction with another remote sensing instrument (either SSI or NIMS) producing one-dimensional temperature scans. The best data of this type were taken during the close approach flybys during orbits I24, I25, I27, I31, I32, and I33 and include measurements of the volcanoes Pele, Prometheus, Pillan, Zamama, Tvashtar, Daedalus, Amarani, Gish Bar, Isum, Emakong, Tupan, and Tohil.

We use heat balance arguments to obtain a new estimate of Io's heat flow that does not depend on assumptions about the temperatures of its thermal anomalies. Our estimated heat flow is somewhat less than 2.2 +/- 0.9 W/sq m. Additional information is contained in the original extended abstract.

Recent Galileo PPR (Photo-Polarimeter Radiometer) results will be shown, including global day and nighttime maps, high latitude regional maps, and high-resolution scans across hotspots and from pole to pole. SO2 vapor pressure, global heatflow, and hotspot power outputs are estimated. Additional information is contained in the original extended abstract.

The "Mitten" (provisionally named Murias Chaos by the International Astronomical Union) is a region of elevated chaos-like terrain in the leading hemisphere of Europa. Its origin had been explained under the currently debated theories of melting through a thin lithosphere or convection within a thick one. Galileo observations reveal several characteristics that suggest that the Mitten is distinct from typical chaos terrain and point to a different formational process. Photoclinometric elevation estimates suggest that the Mitten is slightly elevated with respect to the surrounding terrain; geologic relations indicate that it must have raised significantly from the plains in its past, resembling disrupted domes on Europa's trailing hemisphere. Moreover, the Mitten material appears to have extruded onto the plains and flowed for tens of kilometers. The area subsequently subsided as a result of isostatic adjustment, viscous relaxation, and/or plains loading. Using plate flexure models, we estimated the elastic lithosphere in the area to be several kilometers thick. We propose that the Mitten originated by the ascent and extrusion of a large thermal diapir. Thermal-mechanical modeling shows that a Mitten-sized plume would remain sufficiently warm and buoyant to pierce through the crust and flow unconfined on the surface. Such a diapir probably had an initial radius between 5 and 8 km and an initial depth of 20-40 km, consistent with a thick-lithosphere model. In this scenario the Mitten appears to represent the surface expression of the rare ascent of a large diapir, in contrast to lenticulae and chaos terrain, which may form by isolated and clustered small diapirs, respectively.

A wealth of data about Loki, the most powerful volcano on Io, has been collected and here, we try to begin synthesis of these data. These data suggest periodic lava lake overturn. Further, these eruptions may be truly periodic, and therefore predictable. Additional information is contained in the original extended abstract.

We attempt to improve on previous Io heat flow estimates by using higher resolution data from Galileo Photopolarimeter Radiometer (PPR) and improved thermophysical models of the surface, including finite thermal inertia, the pedestal effect, and disk-resolved radiance.