Active Thermal Control System Pump Trade Study for Use on Dream Chaser® Spaceplane Cargo System

Sierra Nevada Corporation’s Dream Chaser® spacecraft is under contract with NASA to resupply cargo to the International Space Station (ISS) beginning in 2021. One of the major subsystems of this spacecraft is the Thermal Control System (TCS), which maintains the thermal environment of the composite vehicle throughout all mission phases. The TCS maintains a shirt sleeve environment for ISS astronauts working inside the pressurized vehicle. Requirements for the reusable vehicle dictate a lifespan of 15 missions with no planned maintenance between each mission. Implementation of these conditions allows for efficient turnaround time between flights, but generates unique challenges in providing the required motive force necessary to maintain the active cooling loop while creating a robust system that can withstand 15 missions. The pump selection and design is further complicated since it must function during a vertical launch configuration, micro-gravity, and horizontal landing. The TCS team performed a trade study of various pump types, and down selected to a centrifugal pump or a fluid displacement pump. This paper discusses the advantages and disadvantages of the two different pump types, the trade evaluation criteria, and any risks associated with long duration flight for each pump type. After completing the trade study, the data led the team to move forward with a centrifugal pump based on the requirements defined by the customer and available technology.