Alumina Optical Surface Heat Shield For Use In Near-Solar Environment

Experiments indicate that coating a heat shield with alumina can significantly reduce spacecraft temperature during operation near the sun. A thin alumina (Al(2)O(3)) coating applied to carbon-carbon (C-C) reflects the majority of the visible solar irradiance while reemitting absorbed energy in the infrared. Testing on Al(2)O(3)-coated C-C coupons using visible and NIR lasers (from ambient to 1773 K) show that the solar-absorptance-to-IR emittance ratio (alpha(S)/epsilon(IR)) of the Al(2)O(3)-coated heat shield was 0.6 or less. Compared with an uncoated carbon-carbon heat shield, the coated version is at least 12% cooler, enabling thermal insulation mass reductions, improved scientific measurements, and the use of less exotic thermal protection materials.