Columbus APM TCS Design and Development Status

The redesign of Space Station Freedom (SSF) and the requirement of the Columbus programme board to reduce costs have led ESA to change the design and development strategy of the Attached Pressurised Module (APM). A revised APM reference design for integration with the SSF Alpha has been produced with sufficient flexibility to allow adaptation as part of a global space station or to permit operations as part of a European Free Flyer. The main objectives of the redesign have been to simplify the design, reduce the costs and provide increased autonomy from the SSF. The key groundrules for the redesign have been an AR5/ATV launch from the Centre Spatial Guyanais (CGS) into an orbit inclined at 51.6 degrees. The APM has a length equivalent to 5 double racks and a net launch mass of 1200 kg. It will be delivered to the SSF at an altitude of 407 km for a 10-year operational life. Safe disposal will be by ATV. The Thermal Control Subsystem architecture maintains a moderate temperature loop for transportation of waste heat from subsystem coldplates and payloads, and a low temperature loop to remove heat from the ECLSS condensing heat exchanger and cold payloads. Each loop interfaces with a separate heat exchanger of the SSF. Only two pumps will be used, in contrast with previous design. In the event of pump failure, operations can continue in a single loop configuration with SSF heat exchangers in series. Potential alternative solutions are under evaluation to guarantee the maximum payload support capability after a pump failure and avoid the necessity of loop reconfiguration. The necessity to have a lighter APM-5 implies a reduced mass target for TCS components, whose design has been reviewed with the objective of mass saving.