A Cryogenic Heat Transport Loop for Space-Borne Gimbaled Instruments

A high-performance cooling system for gimbal-mounted infrared sensors is a critical need for future space-based target acquisition and tracking systems. A candidate approach uses a high performance cryocooler remotely located on the spacecraft platform combined with a high conductance, cryogenic heat transport system to exchange heat from the sensors to the cryocooler. The heat transport system must have high conductance, produce minimal parasitic heat loads, and impose minimal torque on the gimbal, in addition to the typical space requirements of light weight, compactness, and reliability. To meet these challenging requirements, we propose to develop a single-phase gaseous heat transport loop consisting of a miniature cryogenic circulator, ultra-flexible transfer lines, and compact heat exchangers. The circulator design has heritage in the unit developed by Creare for the Hubble Space Telescope, which has operated at 70 K for over 4.5 years with no change in performance. During Phase I, we proved feasibility of the concept by (1) producing preliminary designs of candidate heat transport systems for the Space Tracking and Surveillance System, and (2) successfully executing flexibility and life tests on the transfer lines at cryogenic temperatures. During Phase II, we will build and test the heat transport system at cryogenic temperatures.