Lockheed Martin’s Advanced Technology Center has developed a series of long life small cryocoolers for avionics and space sensor applications. We report the technology readiness level and performance of the Lockheed Martin Space Mini cryocooler thermal mechanical unit (TMU). The design is based on the standard unit originally developed for NASA/GSFC and a higher capacity developed for ESA. This Mini TMU provides a single stage cold head separated from the compressor and is an ideal choice for medium size cryogenically cooled instruments.
Lockheed Martin’s Advanced Technology Center, part of Lockheed Martin Space Systems Company, has developed a series of long life microcryocoolers for avionics and space sensor applications. We report the development and testing of three varieties of single-stage, compact, coaxial, pulse tube microcryocoolers. These coolers support emerging large, high operating temperature (100-150K) infrared focal plane array sensors with nominal cooling loads of 200-2000 mW, and all share long life technology attributes used in space cryocoolers, which typically provide 10 years of continuous operation on orbit without degradation. These three models of microcryocooler are the 345 gram Micro1-1, designed to provide 1 W cooling at 150 K, the 450 gram Micro1-2, designed to provide 2 W cooling at 105 K, and the 320 gram Micro1-3, designed to provide 300 mW cooling at 125 K while providing the capability to cool the IR focal plane to 125 K in less than 3 minutes. The Micro1-3 was also designed with a highly compact package that reduced the coldhead length to 55 mm, a length reduction of more than a factor of two compared with the other coldheads. This paper also describes recent design studies of 2-stage microcryocoolers capable of providing cooling at 25-100K. LMSSC is an industry leader in multiple-stage coolers, having successfully built and tested eight 2-stage coolers (typically cooling to 35-55K), and four coolers with 3 or 4 stages (for cooling to 4-10K). The 2-stage microcryocooler offers a very low mass and compact package capable of cooling HgCdTe focal planes, while providing simultaneous optics cooling at a higher temperature.
Lockheed Martin's Advanced Technology Center (LM-ATC) has delivered a flight model cryocooler system for NASA's Geosynchronous Imaging Fourier Transform Spectrometer (GIFTS). This system was developed as a New Millennium Program to demonstrate technologies, which enable revolutionary science. One of the new technologies for future generation remote sensors is the two-stage pulse tube cryocooler. This cooler is presently being integrated with the spectrometer at Space Dynamics Laboratory (SDL) in preparation for system tests.
In addition, a similar two-stage Engineering Model cryocooler was developed for a different program. LM-ATC's pulse tube cryocoolers employ a unique staging arrangement, resulting in high power efficiency, compact and efficient packaging, and interfacing and excellent reliability. They are robust and simple, consisting of a two-stage coldhead with no moving parts, driven by a moving magnet compressor and powered by a high-efficiency electronic controller that includes ripple suppression and vibration cancellation. The design is a "split" system in which the compressor and cold head are separated by a transfer line. The approach allows on orbit adjustment of the relative cooling loads and temperatures of the two stages.
These two stage cryocoolers are developed for simultaneous cooling of the focal plane and the optics at two different temperatures. The electronic controller provides precise temperature control of the focal plane and also provides a vibration reduction loop. The total mass of these systems, including electronics, is approximately 9 Kg.
This paper presents the performance and characteristics of these systems.