CHARACTERIZATION OF REFLECTED LIGHT FROM THE SPACE POWER SYSTEM H. B. LIEMOHN, D. L. TINGEY, D. H. HOLZE, AND B. R. SPERBER BOEING AEROSPACE COMPANY SEATTLE, WA 98124 Presented at the DOE/NASA Satellite Power System Program Review April 22-25, 1980 University of Nebraska - Lincoln The development and operation of a Space Power System would place very large structures in orbit around earth for several decades. Sunlight reflected off such structures, particularly specular components from large flat areas, is expected to create ground illumination that will attract observers. In order to assure that this illumination does not exceed the irradiance tolerances of the eye, reflections from these satellites must be carefully controlled by vehicle orientation and surface specifications. The solar power satellite (SPS) at geosynchronous altitude (GEO) has 55 km2 of glass covered solar cells that are oriented normal to the sun, as well as a 1 km2 microwave antenna. Transportation of construction materials from low earth orbit (LEO) to GEO requires 23 Orbit Transfer Vehicles (OTVs) that have 1.6 km2 solar panels oriented normal to the sun during their 6 month transits. The Staging Base (SB) at LEO, that accommodates OTV fabrication and cargo transfer, consists of 0.5 km arms protruding from a .44 km2 open grid aligned with its orbit plane. Diffuse reflections would make the SB/OTVs readily discernible in the daytime and the OTVs and SPSs observable all night (except during eclipse). Sporadic specular glints would appear on the ground from the OTVs and SPSs near the midnight meridian, from the solar panel surfaces of OTVs during LEO fabrication, and from OTVs near LEO at dawn and dusk. The ground level irradiance has been evaluated for several unusually bright configurations using the Baseline System Design. For example, the present microwave antenna on SPS produces ground irradiance comparable to that from the full moon during operations around the equinoxes. Various modifications in the design and operation are suggested to reduce the brightness of these reflections.
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