Active versus standby redundancy for improved cryocooler reliability in space
Long-life space cryocooler applications, such as NASA’s Atmospheric Infrared Sounder (AIRS) instrument, require that the cryocooler system possess a very high level of reliability. This need for high reliability not only demands that high reliability coolers be used, but often requires that some form of redundancy be incorporated. One common implementation is standby redundancy; however, active redundancy is another equally viable choice. Recently, experience with both types of redundancy has been gained with the AIRS instrument. The AIRS cryocoolers were initially designed and launched as standby redundant units; they were then switched over to active redundancy after six months of in-space operation.
AIRS PFM Pulse Tube Cooler System-Level Performance
JPL’s Atmospheric Infrared Sounder (AIRS) instrument is being built to make precision measurements of air temperature over the surface of the Earth as a function of elevation; the flight instrument is in the final stages of assembly and checkout at this time, and uses a pair of TRW pulse tube cryocoolers operating at 55 K to cool its sensitive IR focal plane.
Thermal Performance of Stirling-Cycle Cryocoolers: A Comparison of JPL-Tested Coolers
Spacecraft cryocoolers continue to attract interest in the space science community. To date, many Stirling cycle cryocoolers have been characterized by JPL in a number of performance areas including thermal performance. A number of factors are used to evaluate the efficiency and cooling power of cryocoolers at cryogenic coldtip temperatures. A comparison of the measured thermal performance of several cryocoolers is presented.