Charon: An Ice Machine in the Ultimate Deep Freeze

The spectrum of Charon obtained by NIRI at Gemini North. It is centered at 2.2 microns for the sub-Pluto (top) and anti-Pluto (bottom) hemispheres of Charon. The solid line denotes the best fit for a model of a surface with ammonia hydrate and water ices. The dashed lines are data that indicate the position of the ammonia hydrate feature. The sub-Pluto and anti-Pluto ammonia hydrate minima are located at 2.2131 and 2.1995, respectively. (The error bars represent 1 sigma.).