Surviving the Lunar Night

Advanced Cooling Technologies, Inc. (ACT) is excited to announce a $5 Million NASA Sequential Phase II SBIR Program Award, “Development of Lunar Vehicle and Payload Thermal Control Systems for Extreme Lunar Environments”. As part of this project, ACT is subcontracting Astrobotic to provide their industry experience with lunar landers and rovers, including system-level architecture and critical design requirements. Astrobotic will validate the technology using their Peregrine lander, Griffin lander, and CubeRover thermal system architectures as a baseline.

The lunar day and night cycle poses a significant thermal challenge to small, low-power payloads, rovers, and landers. Due to the slow rotation of the lunar surface relative to the Sun, the environmental temperature drops to below 100K for approximately 14 Earth days. In order to enable long-duration science missions on the lunar surface, it is necessary to maintain the electronics above survival temperature during the lunar night. The Apollo astronauts went to the moon during the early lunar morning, which is a relatively benign thermal environment. In contrast, lunar landers and rovers must be able to survive and function over multiple lunar day/night cycles. It has been estimated that for every watt of power supplied by batteries during the lunar night, an additional 5kg of battery mass is required. Surviving multiple lunar cycles without the use of active power sources for heating and cooling will require the advanced thermal management techniques that will be developed in this program. The proposed program will develop systems that operate during the day to reject waste heat with high thermal conductance, and survive the lunar night with high thermal resistance to minimize heat losses.

Figure 1. Conceptual illustration of combined Thermal Switch and Variable Conductance Thermal Control System for Lunar Landers and Rovers. (a) During the day the electronics are generating heat and the thermal switch and VCHP is ON. Heat is rejected to the radiator and stored in the liquid Phase Change Material (PCM). (b) At night, the thermal switch is OFF, and the VCHP is shut down, with Non-Condensable Gas (NCG) blocking the condenser and adiabatic section. Thermal resistance between electronics and sink is maximum. The PCM cools down and freezes, supplying heat to maintain the temperature of the electronics.

The principal objectives of the proposed program are to develop high technology readiness level (TRL) thermal “toolbox” elements and develop complete thermal control system designs for lunar landers, rovers, and habitats.

The reference architecture, illustrated in Figure 1, consists of passive elements for (1) Heat Acquisition, Heat Collection from electronics, (2) Heat Transport, (3) Heat Rejection, and (4) Heat Storage. These are toolbox elements, that can be combined in a number of different ways, depending on particular design/mission needs and constraints.

Devices to be incorporated in the thermal control systems include:

Heat Acquisition: High Conductivity (HiK™) plates with embedded heat pipes, space copper/water heat pipes, ICE-Lok™ improved Wedge locks
Heat Transport: Loop Heat Pipes (LHPs) with Thermal Control Valves (TCVs), Warm and Cold Reservoir Variable Conductance Heat Pipes (VCHPs), VCHP loops, and Two-Phase Thermal Switches (TPTS)
Heat Storage: Phase Change Material (PCM) heat sinks
Heat Rejection: Radiators with embedded Constant Conductance Heat Pipes (CCHPs), LHP radiators, and Variable View Factor Radiators

“Since 2010, ACT R&D has been working with NASA Marshall and NASA Johnson Space Centers to develop cutting edge thermal control systems for Lunar Landers and Rovers,” said Bill Anderson, Chief Engineer at ACT, and Principal Investigator for the program. This program gives us an opportunity to further mature ACT’s technologies and integrate them into complete Lunar thermal control systems.”

The thermal control systems will be jointly developed by ACT and Astrobotic and tested in Astrobotic’s lunar test chambers. “At the heart of lunar landers, rovers, and other lunar mobility systems is a complex thermal management system that enables us to operate in the extreme heat and extreme cold of the lunar surface,” said Jay Eckard, Technical Project Manager at Astrobotic, “We’re really excited about the work we are doing with ACT, not only for the capabilities this technology can add to our own product lines but also what it can provide to the entire space industry.”

SPACE NEWS ARTICLE

About ACT:

Advanced Cooling Technologies, Inc. (ACT) is a premier thermal management solutions company, providing design and manufacturing services to meet our global customers’ needs across all points of the product lifecycle. We serve our customers’ thermal management and energy recovery needs in diverse markets including Defense, Aerospace, Electronics, HVAC, Medical, Enclosure Cooling, and Calibration Equipment. ACT specializes in providing performance and cost-optimized thermal management technologies and solutions.

Research & Development remains the essential ingredient for our continued success. R&D continues to lead the product and market diversification efforts and shapes the innovative solutions provided to our customers. A snapshot of current R&D programs reveals diverse activities ranging from developing thermal protection materials for space reentry vehicles to investigating nanoscale heat transfer in next-generation electronic devices to designing mega-watt class cooling systems for power plants.