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