Reflectance of Titan’s surface from DISR

This reflection spectrum of the surface was obtained after landing using an on-board lamp (red line). The surface is dark and brownish. The reflectivity shows absorption probably due to water ice. The slope of the reflectivity in the infrared is unlike any existing laboratory measurements. Spectra of two different organic tholins (black lines) are shown for comparison. These laboratory analogues of Titan’s photochemical end-products are consistent with the visible spectrum of the surface but cannot explain its infrared reflection spectrum.