Innovative Inorganic Electrochromic Thermal Control Systems

"Thermal control coatings are an important part of any spacecraft. Smaller light weight satellites are especially sensitive to radical changes in their thermal environment as they orbit the earth. An intelligent thermal management system is vital for thesesatellites. This program will develop a new design for an inorganic solid state electrochromic (EC) variable emittance coating with an emittance modulation range from 0.2 to 0.8. This is a substantial improvement in emittance modulation for EC coatings.Prototype coatings will be applied to substrates of silicon or germanium wafers, which also serve as infrared (IR) transparent windows, to create variable emittance devices (VEDs). These devices may be applied to satellite surfaces for thermal control.Sample devices will be subjected to 2000 equivalent sun hours of ultraviolet (UV) radiation in order to demonstrate the feasibility of their use mid-earth to geosynchronous orbits. These designs will be optimized for range of emittance modulation anddurability. The emittance modulation range will be further increased by adding one or more IR antireflective (AR) coatings to the substrates/IR windows. This EC technology will benefit the military and civilian aerospace industry by improving thermalstability of spacecraft and space structures for commercial and military applications. Successful completion of the Phase I program will produce a new design for an electrochromic variable emitta