The four Galilean moons of Jupiter – Io, Europa, Ganymede, and Callisto – together provide a laboratory for studying what effect internal vs. external factors have on the surfaces we see today on Solar System moons. This project will characterize the surfaces of the four Galilean satellites using observations from telescopes operating at radio wavelengths. Observing all targets in the same way allows for a direct comparison between them. This shows how the unique characteristics of each moon, such as Ganymede’s magnetic field or Io’s high internal heating, affect its surface. The program will also develop workshops to train students in effective public communication and the creation of outreach content. This training will enable the students to showcase their own PhD topics at public science events.<br/> <br/>This project will characterize the thermophysical surface properties of the four Galilean satellites and how they vary across these satellites’ surfaces, constraining hemisphere-scale variations and identifying and interpreting localized thermal anomalies. The galilean moons present a range of internal heat flows, from the powerful tidal heating and volcanism of Io through the cratered, inactive surface of Callisto, and correspondingly hold records of different time periods in their surface features. The project will make use of multi-wavelength datasets (microns to centimeters, with an emphasis on recent ALMA and VLA data) in order to provide views of the surface at a range of depths down to half a meter. By applying sophisticated thermophysical models to spatially resolved data, the project can isolate specific latitudes, longitudes, and geological terrains and investigate how material properties (and potentially heat flow) correlate with surface location and terrain type. The resultant 3D (latitude, longitude, depth) maps of temperature and density will aid in the interpretation of the processes at work on these moons both locally and globally. The results of this study are timely because early JWST data, as well as upcoming data from the NASA Europa Clipper and ESA JUICE missions, will provide views of the galilean satellite surfaces at complementary thermal wavelengths.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.