The surface energy budget is an important input parameter for modelling the dynamical processes of the KOSI samples. In order to calculate the absorbed fraction of the irradiation the directional-hemispherical albedo of the samples must be known. The albedo is calculated from the spectral radiance factor in the wavelength range from .36 &mgr;m to 2.5 &mgr;m. All samples were analysed before and after the experiments. The spectra of the experiments KOSI 3, 4 and 6 have been measured under three different illumination geometries.

During the KOSI sublimation experiments a dust mantle 1 to 5 millimeter thick forms on top of the samples. This changes the spectrophotometric properties of the sample surfaces in terms of scattering characteristics and water ice absorptions at 1.5 &mgr;m and 2.0 &mgr;m. Water ice absorptions observed after the experiment may be partly due to frost contamination. ¿American Geophysical Union 1991