This innovation is a concept for a novel thermal architecture that would enable a day-long surface mission on Venus. A Venus lander mission could last much longer than a few hours on the surface of the planet by absorbing heat from the Venus environment, and from the electronics within the lander, by using an expendable fluid cooling system. The fluid would evaporate in the structural shell, absorbing heat coming from the ambient environment, keeping the shell relatively cool compared to the ambient temperature. The evaporating fluid would create a liquid flow from a reservoir used to cool electronic components within the lander. The liquid reservoir must be contained within the lander structure to serve as a heat sink to maximize the lander lifetime on the surface. A pressure tank would be used to bring the fluid to a point where it could boil and vent into the Venus atmosphere.
The cooling system concept has three basic elements: a pressurized storage reservoir of the coolant fluid; a single-phase, low-temperature heat exchanger that absorbs heat from the electronics; and a high-temperature, two-phase heat exchanger where the fluid is boiled into a vapor by absorbing heat from the structural shell. The latent heat of vaporization is able to absorb ≈10 times more heat per unit mass than the heat of fusion of a typical phase change material. The vapor from the coolant system is vented to the atmosphere. Venting would not be needed for the first few hours on the surface, so atmospheric science could be done early and not be influenced by venting. The ammonia coolant vapors would have a lower density than the planet’s carbon dioxide atmosphere, and would tend to rise above the lander naturally and likely not affect continued atmospheric science measurements.
This work was done by Michael T. Pauken of Caltech, and Sheldon Jeter and Christopher J. Fernandez of the Georgia Institute of Technology for NASA’s Jet Propulsion Laboratory. NPO-49708
This Brief includes a Technical Support Package (TSP).
Expendable Cooling System for Venus Lander Concept
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Overview
The document is a technical report detailing the development of an expendable cooling system designed for a one-day Venus Lander mission. Authored by Dr. Michael T. Pauken and colleagues from the Jet Propulsion Laboratory and Georgia Institute of Technology, the report outlines the objectives, methodologies, and findings of the research aimed at enabling extended surface operations on Venus, a planet known for its extreme temperatures and pressures.
The primary goal of the project was to create a thermal control architecture that would allow a Venus Lander to operate for an unprecedented duration of up to one day, significantly surpassing the operational lifetimes of previous missions, such as the Soviet Venera Landers, which lasted less than two hours. The proposed system utilizes an expendable coolant to manage heat generated by onboard electronics and the structural shell of the lander, thereby facilitating a more interactive scientific exploration process.
The report describes a series of tasks undertaken to achieve this goal. Task 1 involved defining the mission's scope and capabilities, establishing target budgets for mass, volume, power, and energy requirements. Task 2 included a collaborative workshop with Georgia Tech to refine the design parameters for the thermal subsystem. Task 3 focused on gathering thermodynamic and heat transfer data for potential expendable coolant fluids, such as ammonia and water, assessing their suitability for the harsh Venusian environment.
Subsequent tasks (4-6) involved developing analytical models for the thermal subsystem, conducting parametric studies to optimize the balance between insulation, phase change materials, and expendable coolant, and building an experimental apparatus to validate the cooling system's performance. The experimental setup demonstrated the system's ability to absorb heat effectively, even under conditions simulating the extreme environment of Venus.
The report includes figures illustrating the thermal architecture and performance comparisons between the expendable cooling system and traditional cooling methods. The findings suggest that the proposed expendable coolant system could significantly enhance the operational capabilities of a Venus Lander, allowing for real-time data analysis and targeted scientific investigations, thus paving the way for more ambitious exploration of Venus.
Overall, this research represents a significant advancement in thermal management systems for planetary exploration, with potential implications for future missions to Venus and other celestial bodies.
