Light Pressure Measurement at DLR Bremen

The solar light pressure exerted on a thin foil is the quantity that determines crucially the performance of a solar sail propulsion technology. Besides the distance from the sun and the relative position of the sail to the sun, the light pressure depends on the quality of the sail surface. The surface quality, especially the reflectivity, degrades by exposing the sail to particle and electromagnetic irradiation under space conditions. This process will be simulated by a test facility at DLR Bremen. By directly measuring the light pressure after exposing the foils to a certain dose yields a kind of integral quantity of the degradation effects. To this end a light pressure measurement facility based on a high precision balance has been developed, completed and tested at DLR Bremen.