Global Shape and Regional Topography of Io: First Galileo Results

Galileo CCD images of Io are much superior in their geometrical precision to the vidicon images obtained by Voyager. In addition, the viewing angles obtained from Galileo in Jupiter orbit yield a more homogeneous coverage of Io's surface than could be obtained during the Voyager fly-bys. Hence, these new data allow us to carry out analyses to determine Io's morphology using a variety of methods, such as control point network analysis, limb studies, stereo image processing, and shadow-length measurements. We focus on control point and stereo analyses in this study. Global shape models may give important boundary conditions for studies of internal structure from theoretical modelling of planetary shapes in tidal equilibrium and gravity data, whereas regional topography may reveal the structure of the crust and variations in conductive heat flow.