Cryogenic Cooler Progress! NASA technology makes significant progress towards a five-year life space cryogenic cooler that weighs less than 15 kilograms and provides 0.45 watts of cooling power at 30 degrees Kelvin for only 75 watts of input power. This cooler at its design point is 50% more efficient than any comparable cooler to date.
The OSAT Sensors and Instruments Technology program competitively selected two industry teams to build technology demonstration cryo-coolers for evaluation at the NASA Goddard Spaceflight Center. The Ball Aerospace technology demonstration cooler exceeds the contract specification by more than 50%. This Ball cryo-cooler produced 0.45 watts of cooling at 30 degrees Kelvin at a total input power of 95 watts. This 95 Watt input power includes 20 watts of losses associated with breadboard electronics. The engineering model electronics (already designed) should eliminate these losses. The overall efficiency of the Ball cooler at its design point is 50% more efficient than any other cooler to date. The Ball cooler weighs less than 15 kg.
The Ball compressor incorporated radial position sensors that have provided proof that the compressor has non-contacting bearings. This feature is unique to the Ball cooler. It essentially guarantees that the cooler will not wear out.
The Ball two-stage Stirling cooler, known as the " 30K cooler," has turned out to be much more than was expected. Everyone, including Goddard personnel, believed that a single-stage Stirling cooler would be ready for flight before a two-stage machine. It now appears that the Ball two-stage cooler will be the first cooler ready for flight with true clearance seals (and therefore with high probability of long life). Goddard has recently completed a set of performance tests that indicate that the Ball cooler has excellent thermodynamic performance even in the 55 - 80 Kelvin temperature range. Thus, the Ball cooler could be useful to a wide variety of programs.
The final step after the technology demonstration model is to build and life-test the engineering model. The engineering model will include the more efficient electronics and use the non-contacting bearings in both the cold and warm ends of the cooler. The engineering model will be completed and life tests begun in either fiscal year 1995 or 1996, depending upon the available level of funding.