Instrument
 

Cryocooler

Cryocooler

 
The GeDs are cooled on-orbit by a single electro-mechanical cryocooler. Recently, under contract to NASA/GSFC, Sunpower Inc. has developed an inexpensive single stage, integral (counterbalanced) Stirling cycle cooler which can provide up to 4W of cooling at 77 K, with an input of 100W. This M77 cryocooler has been designed for operational lifetimes greater than 50,000 hours, using a gas bearing/flexure system to prevent contact of moving parts. In extensive studies over the past two years at GSFC, M77 coolers have been vibrated to the GEVS mandated 14.1 Grms, run under thermal vacuum conditions from -25C to +30C, and life-tested already (continuing) for ~>10,000 hrs. Monitoring during these tests showed no internal contamination of the working gas. Units already tested at GSFC are fully qualified for flight, and will be used for HESSI.  More Diagrams and Illustrations...