Pluto and Charon ’ S Topographic Variance Spectra from Limb Profiles

Introduction: The New Horizons mission [1] revealed Pluto as a geologically active body [2,3] while Charon’s surface is older but also tectonically deformed [4]. Topography can be used to probe the geophysics of these bodies, and can be derived either from stereo observations [5,6] or from limb profiles [7]. In this work we focus on limb profiles and look at the variation of topographic roughness with wavelength to make geophysical inferences [8]. Topography: To derive topography from limb profiles we first locate the limb in an image using Method A from [7]. Then an orthographic projection [9] is used in conjunction with spacecraft location and pointing information to determine the latitude, longitude and radius at each limb location. In Figure 1 we present maps of Pluto and Charon which show limb topography locations and values. Profiles are temporally positioned from right to left in the approach sequence.