Spacecraft Thermal Protection Systems (TPS) Based on Polybenzoxazole (PBO) With Unique UV, Atomic-O and Solar Wind Protective Coatings

Poly(benzoxazole) (PBO) is a new polymeric material extremely promising for external spacecraft structural applications, including, e.g., debris and micrometeoroid shields and crew suits. One of its drawbacks is its reduced resistance to the far-UV and atomic-O. If a well-adhering, protective coating for PBO fibers and sheets could be found, a plethora of space applications would be opened up. In ongoing work with very thin, flexible, Variable Emittance panels for spacecraft thermal control applications, this firm has developed new unique, proprietary, very thin (< 0.4 micron), very light weight coatings which are applied on the top conducting polymer (CP) layer of these devices (the layer which faces the space environment). These coatings provide protection against UV/VUV, atomic-O, Solar Wind and electrostatic discharge in space, and have very high flexibility and very good adhesion. In further work, these coatings were deposited on PBO, and shown to have excellent adhesion and impart good UV protection. The present work seeks to further develop this technology by testing and refining a large number of these coatings on a variety of PBO substrate types. Extensive mechanical, UV and space vacuum testing, and at least one atomic-O and one Solar Wind test, are planned.