Felt Reusable Surface Insulation

FRSI is the same Nomex material as SIP. The FRSI varies in thickness from 0.160 to 0.40 inch depending on the heat load encountered during entry. It consists of sheets 3 to 4 feet square, except for closeout areas, where it is cut to fit. The FRSI is bonded directly to the orbiter by RTV silicon adhesive applied at a thickness of 0.20 inch. A white-pigmented silicon elastomer coating is used to waterproof the felt and provide required thermal and optical properties. The FRSI has an emittance of 0.8 and solar absorptance of 0.32. FRSI covers nearly 50 percent of the orbiter's upper surfaces.