Lessons Learned during the Integration Phase of the NASA IN-STEP Cryo System Experiment

Abstract

The Cryo System Experiment (CSE), a NASA In-Space Technology Experiments Program (INSTEP) Class D Flight Experiment, was developed by Hughes Aircraft Company to validate in zero-g space a 65 K cryogenic system for focal planes, optics, instruments, or other equipment (gamma-ray spectrometers and infrared and submillimeter imaging instruments) that require continuous cryogenic cooling. The system consists of a long-life, low-vibration Stirling-cycle, 65 K, Improved Standard Spacecraft Cryocooler (ISSC), and a diode oxygen heat pipe thermal switch that enables physical separation between the cooling source and the element to be cooled.

A key value of this flight experiment has been the opportunity for Hughes and the Jet Propulsion Laboratory (JPL) to identify and resolve cooler and imaging-instrumentation integration issues that will be encountered when these enabling thermal management technologies are integrated in future space cryogenic cooling systems.

Presented are generic lessons learned from the system integration of cryocoolers for a flight experiment including: launch-vibration restraints for the expander cold-tips, implementation of compressor and expander hysteresis test capability, the design and installation of a high-compliance thermal strap to minimize side loads on the expander, the inclusion of both the cooler as well as its heat rejection materials in the mass calculation, contamination/parasitics, system operations/software, electrical interface requirements, and the safety implications associated with the classification of mechanical components and the radiation environment.