Title of Presentation: Cooling Technology for Large Space Telescopes

Primary (Corresponding) Author: Keith Walyus

Organization of Primary Author: NASA Goddard Space Flight Center


Abstract: The ST9-Large Space Telescope (LST) program plans to develop a system cooling technology, which is applicable to all future IR, Sub-millimeter and Millimeter Telescopes. This includes large 4 K space telescopes like the proposed Single Aperture Far-Infrared Telescope (SAFIR) mission.  This technology will also enhance the performance and lower the risk and cost for other cryogenic missions. The new paradigm for cooling to low temperatures will involve passive cooling using lightweight deployable membranes that serve both as sunshields and V-groove radiators, in combination with active cooling of the membranes with mechanical cryogenic coolers operating to temperatures down to 4 K.  The work we completed was directed towards an L2 orbit however the results are readily applicable to Earth trailing orbits like Spitzer.

The LST mission will develop and demonstrate a multi-layered sunshield, actively cooled by a multi-stage mechanical cryocooler, and further the models and analyses critical to scaling to future missions. The outer four layers of the sunshield cool passively by radiation, while the innermost layer is actively cooled to enable the sunshield to decrease the incident solar irradiance by a factor of more than one million.  The cryocooler cools the inner layer of the sunshield to 20 K, while also providing cooling to 6 K at a telescope mounting plate.  LST will be the first flight of this class of low temperature cryocooler. The technology readiness level of the active cooling technology will achieve a TRL level of 7 following the technology validation flight in Low Earth Orbit.

As part of the New Millennium charter, tests and modeling are tightly integrated to advance the technology and the flight design for “ST-class” missions.  Using commercial off-the-shelf products to develop validated modeling capabilities will allow the results from LST to apply to a wide variety of future missions. The LST mission will “rewrite the book” on cryo-thermal testing and modeling techniques, and validate modeling techniques to scale to future space telescopes such as SAFIR.