Global compositional cartography of Pluto from intensity-based registration of LEISA data

Abstract

In 2015 the New Horizons spacecraft reached the Pluto system and returned unprecedentedly detailed measurements of its surface properties. These measurements have already been integrated into global reflectance, topography and narrow-band multispectral surface maps. However, analysis of the hyperspectral data from the Ralph/LEISA infrared spectrometer, which lets us analyse the surface composition, has until now been confined to the high-resolution encounter hemisphere of Pluto. We use an innovative technique — intensity-based registration — to co-register this high-resolution data with lower-resolution measurements taken during the spacecraft’s approach, and present the first global qualitative composition maps for CH4, N2 and H2O ice, and a tholin-like red material. We compare these maps with the other maps produced for Pluto and study the global extent of the previously-described latitudinal distribution of the surface components, which is relatively longitudinally constant with the exception of Sputnik Planitia. We also correlate these compositional components with geological features and propose physical interpretations, which include: CH4-ice-rich dissected plateaus in high northern latitudes, CH4-rich eroded terrain with N2-rich infill in medium northern latitudes, CH4-rich bladed terrain in low northern latitudes, and a red material belt overlaying H2O ice in low southern latitudes.