Thermal Design Considerations of the Hubble Space Telescope (HST) Science Instrument Control and Data Handler (SI C and DH-2)

Following a failure in side 1 of the HST SI C&DH in September 2008, HST Servicing Mission 4 (SM-4) was delayed so that a SI C&DH Orbital Replacement Unit (ORU) could be qualified for flight. This second generation SI C&DH (SI C&DH-2) included several enhancements which increased its thermal dissipation near critical components. In order to maintain the SI C&DH-2 within its operational temperature limits, several thermal modifications were installed prior to its final qualification testing. This paper presents the thermal modifications performed on the SI C&DH-2, as well as the thermal ground test results and a correlation of the SI C&DH-2 thermal design to flight telemetry.