panels is also feasible. Both conditions will spread specular reflections and reduce the local intensity of ground irradiance by distributing the light over a larger area. For example a 5° misalignment results in a 100- fold reduction in ground irradiance (see equation 2). This misalignment would, of course, be counterproductive to the vehicle reorientation discussed above. Many other structural surfaces in the Space Power System spacecraft are nominally flat for structural convenience alone. Specular reflections from structural beams, astronaut housing on the SB, thermal control surfaces, and propellant storage systems might be drastically curtailed by introducing surface curvature. Diffuse reflections are relatively unaffected by this procedure. Surface Quality. The Baseline Space Power System Design includes many surfaces that have specular characteristics in visible light. This surface quality can be altered for some of the applications without affecting the serviceability of the element. For example, the surface of the SPS antenna is an electrical ground plate that presently is polished aluminum; but its electrical properties at the microwave frequencies of interest would not be affected by surface roughening (etching) on the scale size of visible wavelengths to create a diffuse reflector. Another large shiny surface is the aluminized backside of the solar panels on OTV. These surfaces might be painted without affecting the thermal or electrical quality of the system. Other smaller structures might be converted from specular to diffuse reflectors by etching or coating the material. The front side of the solar cells is covered with glass for ionizing radiation protection; its specularity might be reduced by use of nonglare glass that has an optically rough surface. These reductions in the specular components reappear, of course, as slight enhancements to the diffuse components of reflected 1ight. Clearly there are options available to reduce ground irradiance from sunlight reflections off the Space Power System spacecraft. How effective they would be and how practical they are for overall performance and cost remains to be assessed.
RkJQdWJsaXNoZXIy MTU5NjU0Mg==