WHAT HAVE WE LEARNED ABOUT PLUTO FROM NEW HORIZONS MISSION (Invited Presentation)

The New Horizons mission to the Pluto system flew a high-resolution panchromatic imager (LORRI), a wide-field panchromatic and color imager (MVIC), infrared (LEISA) and ultraviolet (Alice) spectrometers, a radio experiment (REX), and two plasma instruments (PEPSSI and SWAP), which have revolutionized our understanding of Pluto. We now know Pluto to be less dense than other comparably sized KBOs, based on six months of astrometry (for the mass), and imaging and occultations (for the radius). LORRI, MVIC, and LEISA show a heterogeneous surface at all longitudes, with darker, CH₄-poor areas near the equator. At the longitudes of the encounter hemisphere, Pluto's surface shows an astonishing diversity of landforms, including rough northern uplands, scarps and crevasses, smooth N2 plains, craters both bare of volatiles and infilled, and multiple forms of mountains. The combined power of this suite of instruments allows us to investigate the geology not only by high resolution imaging, but also with topography, scattering properties at visible and radio wavelengths, how composition maps to landforms, the interaction of the surface with the lowest levels in the Pluto's N₂ atmosphere, the likely role of the atmosphere in photochemical processing, and the implications for the loss of Pluto's surface volatiles over billions of years.

This work was supported by NASA's New Horizons project.