Low Cost Cryocooler Electronics for Space Missions

ABSTRACT: The objective of the LCCE Program is the development of a flight-qualified LCCE that will support a broad range of mechanical cryocoolers of interest to the United States Air Force. The LCCE will solve a fundamental acquisition problem, namely the absence of affordable, radiation hard cryocooler electronics. A flight-design LCCE will be designed, fabricated, performance tested with cryocoolers, and subjected to environmental testing to achieve Technology Readiness Level (TRL) 6 by the end of Phase II. The present state for space cryocooler electronics acquisition is characterized by point designs, which in turn leads to high costs ($1-2M typical) and long acquisition times (18 months typical). Alternatively, non-radiation hard tactical cryocooler electronics are the other option. Neither meets the requirements for cost-sensitive military spaceflight platforms. The objective state is one in which a low cost (<$300K in small lot built quantity, $100K goal), total dose radiation hard, SEL immune, high reliability, open architecture Cryocooler Electronics exists that support a wide range of cryocoolers of interest to the USAF and DoD. The availability of that design will allow the USG user community to pick the mechanical cryocooler best suited to the mission needs rather than being constrained by electronics TRL and/or availability. BENEFIT: Infrared sensors are used in many applications across the Department of Defense including gun sights, targeting pods on fixed-wing and rotary-wing aircraft, ground based and naval surveillance, unmanned aerial surveillance (UAS) platforms, and satellites. The greatest sensitivity, particularly at mid wave infrared (MWIR, nominally 3 to 7 microns) and above, has traditionally been achieved with intrinsic semiconductor-based detectors. These detectors, which include a broad range of chemistries among which the most common are indium antimonide (InSb) and mercury-cadmium-telluride (HgCdTe), require cryogenic refrigeration for operation. New, competing Quantum Well Infrared Photodetector (QWIP) technology is starting to receive attention, particularly at NASA/GSFC; these detectors also require cryogenic refrigeration to achieve optimal performance. The most demanding applications are the space-borne, high-performance cryogenic IR sensors. In addition to the typical mass and efficiency demands of a military platform, a significant complicating factor is the need for radiation-hard components to survive the harsh space environment. This is the primary cost driver on the IR sensor electronics, including the cryocooler drive and control electronics, because of the high component cost and the circuit design complications caused by limited radiation-hard parts availability. The present approach across industry to meet these coupled performance and environmental requirements centers on custom, point-designs to meet each mission. Each major IR sensor component and electronics module tends to be a point design to meet a particular combination of mission, spacecraft, and payload requirements. This drives up nonrecurring engineering cost and results in long development timelines for each new system. These long timelines and high costs are inconsistent with the procurement needs of ORS and other cost-sensitive space flight missions. The LCCE Program is addressing this problem for the cryocooler electronics. During Phase I, an architecture has been defined that is modular, scalable, affordable, and provides the critical cryocooler operational functionality that typically envelopes the needs of a low cost space mission (high efficiency motor drive and closed loop temperature control). This architecture will be reduced to practice in Phase II, culminating in a flight-design Engineering Model immediately applicable for a wide range of DoD missions.