Spectral mapping and long-term seasonal evolution of Pluto

Abstract

NASA's New Horizons mission has provided a wealth of new data about the Pluto system, including detailed surface geology and volatile distribution maps revealing striking latitudinal and longitudinal variations. We begin by studying the methane distribution and surface colors using data from New Horizons' Ralph/MVIC instrument. From this study we find that Pluto's equatorial region shows a broader diversity of terrains and more stark longitudinal contrasts than the more homogeneous north polar region. Pluto's south polar region is currently in constant shadow and thus was not observed by New Horizons. We consider how this diversity formed and survived in the context of Pluto's extreme Milancovid cycles and resultant "super seasons". Over timescales of roughly 3 million years Pluto's obliquity varies by 23 degrees (between 103 degrees and 126 degrees) while its longitude of perihelion regresses. This pair of cycles create "super season" epochs where one pole experiences a short intense summer and long winter in constant darkness, while the other experiences a short winter and much longer, but less intense summer. Through thermal modeling and volatile sublimation and deposition modeling we determined that Pluto's high obliquity creates conditions at its equator that favor albedo contrast and can support them on million year timescales more effectively than Pluto's polar regions can. Finally, we look ahead to a possible next step in small body spacecraft exploration, a study of Apophis during its 2029 close approach to Earth. Since the earlier portion of this thesis focused on the encounter, data collection, and scientific analysis portion of a spacecraft mission (New Horizons), we go full circle by exploring the early stage of the