anism and support structure which has also been used in orbit. The Skylab Apollo Telescope Mount (ATM) solar arrays were successfully deployed using the same basic concept that SD will use (i.e. a scissors arm with cable actuator). The SD power module will incorporate all the successful radiator technologies demonstrated previously. Building on this technology provides a low risk and low cost approach to producing a flight qualified radiator. For the other two assemblies, the receiver and concentrator, a strong base has been developed since 1984 with the infusion of over $20 million of NASA Advanced Development, Contractor Internal Research and Development and NASA Supporting Development Resources. For the receiver assembly, a strong technology base involving thermal storage materials compatibility, mechanical strength, thermal energy storage performance, and receiver thermal performance has been developed. Over 5000 hours of exposure of the thermal storage containment materials to the LiF-CaF2 salt show negligible corrosion. In addition, extensive testing at Lewis and at contractors has shown that the thermal performance is completely verifiable by ground testing and analysis (i.e. no flight test is required). Also, tests conducted by Allied-Signal with a single tube segment of the receiver has verified the operation of the baseline thermal energy storage configuration. Finally, a full-scale advanced development CBC receiver for a 25 kW SD system is being built at the Boeing Aerospace Corporation and will be tested during the summer of 1989. Rocketdyne, meanwhile, has completed an impressive system demonstration test at their Santa Susanna test site in which a receiver unit with integral thermal energy storage was mounted on a Vanguard concentrator and successfully demonstrated essentially uniform receiver/thermal storage capability. Key accomplishments have been realized in concentrator reflective and protective coatings, optical characterization, and structural rigidity. The Harris corporation, Lewis Research Center, and 3M have demonstrated the reflective capability of the individual facets and the resistance of protective coatings to atomic oxygen. In addition, a full scale concentrator (19 panels) has recently been fabricated by the Harris Corp. A successful seven-panel assembly and repeatability test was completed recently. The concentrator is now at Lewis Research Center for a series of optical tests. In conclusion, a strong technology base exists for the development of the Solar Dynamic power module system. On-orbit Assembly On-orbit assembly of the SD modules will be accomplished using assembly equipment developed for the baseline phase of the Space Station Freedom Program (SSFP). In addition, assembly of the SD modules will employ many of the techniques developed and performed on-orbit during the baseline phase, such as those required for Photovoltaic (PV) module assembly. The assembly concepts for either phase, however, will require extensive testing and evaluation as SSFP hardware matures. The text below provides a brief overview of the SD module assembly concept. Assembly of the SD modules will rely on the Mobile Servicing Center (MSC) for transporting equipment to the assembly area outboard the alpha gimbal and positioning components for installation. The MSC will also serve as a work platform for the Extravehicular Activity (EVA) required for SD module assembly. Details about the MSC are provided in reference [5]. The Astronaut Positioning System (APS) attached to the Mobile Transporter (MT) on the MSC will position the EVA crew to make structural and utility connections after SD module components have been positioned
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