The development of high-temperature composite solar array substrate panels for the messenger spacecraft

The MESSENGER (MErcury Surface, Space, ENvironment, GEochemistry, and Ranging) spacecraft will be the first spacecraft to orbit the planet Mercury. Designed and built by The Johns Hopkins University Applied Physics Laboratory (JHU/APL), the spacecraft will orbit the planet for one year. In order to reduce cost and schedule of this NASA Discovery Mission, the solar arrays were required to be constructed of conventional, space-qualified materials. System thermal, mass, and stiffness requirements dictated that the panel facings be fabricated from a high thermal-conductivity and stiffness pitch-fiber composite material capable of withstanding short-term temperatures as high as 270C. A toughened, 177oC-curing cyanate ester composite material resin system with extensive flight heritage was chosen, with a post-cure used to extend the glass-transition temperature closer to the maximum predicted temperature. A lengthy development program was conducted at JHU/APL to provide assurance that the materials and processes chosen were capable of performing under such a demanding thermal environment. The results of this program will be applicable to other high-temperature spacecraft applications of advanced pitch-fiber cyanate ester composite structures.