Thermal Vacuum Qualification Testing of the International Space Station Photovoltaic Radiators 1999-01-1973
The Photovoltaic Radiator (PVR) of the International Space Station (ISS) is a critical component of the Space Station’s thermal control system. It will cool the photovoltaic power system electronic equipment and the batteries used for power storage. The PVR will also provide environmental cooling for the service module during early phases of the Space Station.
Prior to on-orbit operation, verification testing of the PVR was required to ensure the Orbital Replacement Unit (ORU) would operate as expected in the extreme on-orbit thermal environments. The on-orbit operational requirements included extreme thermal gradients, thermal cycles, and a range of coolant temperatures and flow rates, ORU pressure drop, deployment time, and electrical power consumption. The PVR ORU was tested in the world’s largest vacuum chamber at NASA Lewis Research Center’s (LeRC) Plum Brook Station Space Power Facility (SPF) located at Sandusky, Ohio. Test operations included the combined efforts from Boeing Canoga Park, NASA-LeRC, NASA-Plum Brook Station, and Lockheed Martin Vought Systems. Personnel from NASA-JSC, NASA-KSC also oversaw various aspects of the tests. These efforts included hardware and software as well as the managerial, engineering and technical expertise necessary to set-up and conduct the test.
Testing of the PVR included both performance testing of the radiator’s capability to reject heat in a thermal vacuum environment at various coolant temperatures and flow rates, and demonstration of the capability of the radiator to deploy and retract in its intended operational environment. This paper describes the test findings and the efforts required to ensure the ORU would operate as expected. Lessons learned as a result of these tests are also presented.