Pluto Ices: Spectra, Geology, and Timescales
Session 3.02 Dwarf Planets / Ices
Tuesday 06-25 | 09:30 - 09:50

Pluto shows a variety of ices on its surface, detectable in near-infrared spectra from space-based or ground-based telescopes and NASA's New Horizons spacecraft. Some of these ices (N2, CO, and CH4) are volatile enough to move between Pluto's surface and its tenuous atmosphere. Other of the ices (H2O, sometimes with trace NH3) reveal Pluto's bedrock. Still other species (C2H6 and reddish material likely composed of large organic molecules) are photochemical products, formed either in the atmosphere or on the surface. Near-IR spectra (1.25 to 2.5 micron) were taken by New Horizons shortly before its 2015 closest approach. Spectra of Pluto's encounter hemisphere were acquired with a spatial resolution of 6–7 km per pixel, or about 365 pixels across Pluto's 2378-km diameter. This scale is fine enough to allow correlation with geologic features.

One area of recent interest is the ice patterns in Pluto's craters at low-to-mid latitudes west of Sputnik Planitia. A collection of craters, for which New Horizons measured albedos, colors, topography, and infrared spectra, show distinctive patterns of volatile ice. These patterns may allow us to tell whether the ice is sculpted on the timescale of Pluto's day (6.4 Earth days), its year (248 Earth years), or its obliquity cycle (2.8 million Earth years).

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