Design Considerations and Thermal Analyses of the Space Telescope Imaging Spectrograph (STIS) Thermal Interface Kit (STIK) 2000-01-2271
The Space Telescope Imaging Spectrograph (STIS) was installed on the Hubble Space Telescope (HST) during the HST's Second Servicing Mission (SM-2) in February 1997. Since the HST was deployed in April 1990, the effective thermal sinks seen by the spacecraft's science instruments have increased due to a degradation of the multilayer insulation (MLI) on the external surfaces of the HST and due to the increased power dissipated in the HST's aft shroud by the second and third generation science instruments. In order to maintain the instruments detectors at their required temperatures, the Aft Shroud Cooling System (ASCS) was designed and will be installed during the HST's Servicing Mission 3B (SM-3B) which is scheduled for July 2001.
The third generation science instruments, the Advanced Camera for Surveys (ACS) and the Cosmic Origins Spectrograph (COS), will be installed during Servicing Missions 3B and 4, respectively, and will be designed with the thermal interface needed to connect them to the ASCS. However, since STIS was designed, built and installed on HST before the ASCS was developed, it has no direct thermal interface for connection to the ASCS.
STIS was originally designed with internal heat pipes, which carry the heat from the Multi-Anode Microchannel Array (MAMA) detectors to a copper radiator plate on the instrument's aft bulkhead. The power is then radiated to the HST's aft shroud environment. The STIS Thermal Interface Kit (STIK) has been designed to utilize and improve these heat rejection capabilities by attaching a thermal pressure plate onto the existing copper radiator and connecting it through a Capillary Pump Loop (CPL) directly to the ASCS.
This paper describes the design of the STIK and presents the thermal analyses of the three new expected STIS operational states.