Active thermal control for an advanced power platform

Effective use of the Shuttle Orbiter during the operational phase will require the provision of electrical power from free-flying power platforms which will interface with the Orbiter. Such platforms present unique requirements for active thermal control based upon the long life and high heat load requirements which will be necessary to provide 25 kW or more of electricity to the Orbiter and payloads. This paper will present key issues in the design of these active thermal control systems (ATCS) and will discuss potential solutions intended to ensure maximum effectiveness of advanced power platforms. Such issues include proper selection of coolant fluid for the power platform and payload loops; selection and development of thermal control surfaces for five-year life; the use of off-the-shelf hardware vs development of unique hardware, central vs decentralized control of the ATCS; system life and reliability as a factor in determining redundancy and the possibility of on-orbit EVA maintenance; and the interfaces between the power platform and the Orbiter and payloads.