Bench cooling the Thematic Mapper

The present investigation is concerned with the bench cooling system which was developed in conjunction with the Thematic Mapper (TM), a second-generation earth resources sensor. A small, permanently evacuated dewar, which is carried into space with the instrument, is employed to provide thermal isolation for bench cooling IR detectors of many space-borne instruments. This approach has, however, a number of disadvantages. The system designed for cooling the TM makes, therefore, use of a new approach, involving a temporarily evacuated, take-apart dewar in combination with a temperature-controlled Joule-Thomson cryostat.