Measuring Earth-to-Space Contrast Transmittance from Ground Stations

Inherent object and background radiance, beam transmittance through the atmosphere, and sky radiance are all measurable from a ground station. It is shown how, in the visible sectrum, the sky radiance and beam transmittance may be used to compute the path radiance for orbital downward paths of sight. Thus, the components for calculating apparent radiance, apparent contrast, and the contrast transmittance from earth to space are measurable from a ground station. our in-flight experiments were conducted to obtain measurements of contrast transmittance for comparison with measurements made simultaneously at ground stations. The in-flight and ground-based measurements are in good agreement.