Cryogenic/Thermal System for the SIRTF Observatory
The Space Infrared Telescope Facility (SIRTF) Observatory will be launched in the year 2001 and will provide unprecedented sensitivity to explore the birth and evolution of the universe. The Science Instruments will be maintained at a temperature of 1.4 K inside a superfluid helium cryostat. The telescope is located outside the cryostat and will be warm at launch. Helium effluent will vapor cool the telescope and cryostat vacuum shell to their required 5.5 K operating temperature. This is made possible by a multistage thermal system that controls Spacecraft and Sun heat inputs to the telescope and cryostat to very low levels. The system achieves this by using heat rejection to space, low-thermal conductance alumina/epoxy truss supports, miniature electrical cables, and radiation shields to block radiation from the Spacecraft elements. The preliminary design and predicted performance of this unique cryogenic/thermal system are described.
KeywordsOuter Shell Star Tracker Heat Rejection Helium Bath Shell Temperature
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