to spectroscopy of Titan’s hydrocarbon lakes

[1] Reflectance spectroscopy of outer solar system bodies provides direct observations for interpreting their surface compositions. At Titan, the Cassini spacecraft revealed dark patches in the surface reflectance at 2 and 5 mm, interpreted as hydrocarbon lakes forming seasonally through a methane cycle. Whereas the composition of planetary materials in the solar system has been inferred from characteristic absorption bands, identification of phase states (liquid versus solid) on dynamic planetary surfaces requires laboratory reflectance ratio measurements at relevant temperatures. Using visible and near-infrared radiation from the National Synchrotron Light Source (NSLS), reflectance ratios of solid (single crystal) versus liquid CH4 were measured at temperatures from 50–100 K. Although the wavelength and shape of the characteristi