Surface Compositions Across Pluto and Charon
  The New Horizons spacecraft mapped colors and infrared spectra across the encounter hemispheres of Pluto and Charon. The volatile ices CH$_4$, CO, and N$_2$, that dominate Pluto's surface, have complicated spatial distributions resulting from sublimation, condensation, and glacial flow acting over seasonal and geological timescales. Pluto's H$_2$O ice "bedrock" is also mapped, with isolated outcrops occurring in a variety of settings. Pluto's surface exhibits complex regional color diversity associated with its distinct provinces. Charon's color pattern is simpler, dominated by neutral low latitudes and a reddish northern polar region. Charon near infrared spectra reveal highly localized areas with strong NH$_3$ absorption tied to small craters with relatively fresh-appearing impact ejecta. 
W.M. Grundy, R.P. Binzel, B.J. Buratti, J.C. Cook, D.P. Cruikshank,   C.M. Dalle Ore, A.M. Earle, K. Ennico, C.J.A. Howett, ...
astro-ph.EP