Demonstration of Liquefaction for Lunar and Martian Surfaces using Tube-on-Tank Heat Exchanger with an Integrated Cryocooler and Prototype Lander Tank

As in-situ resource utilization (ISRU) concepts and systems emerge, applicable technologies are being developed and matured in tandem. Although there are many different ways to use the resources found on other bodies, one of the most prevalent applications suggested is manufacturing propellants. One of the key technologies for the eventual use of these propellant-production-based ISRU systems is the liquefaction and storage of the produced propellants. The most-mentioned propellant combinations include oxygen-hydrogen and oxygenmethane. The liquefaction of oxygen in these systems will differ from oxygen liquefaction systems on Earth due to the requirements, which are more highly constrained for efficiencies driven by mass and power as opposed to cost. These systems have been developed conceptually and many of the components have been tested previously or are in development. However, the need to demonstrate the system-level operations still exists. The demonstration of a prototypical oxygen liquefaction system using tube-on-tank broad area cooling was completed to gain a better understanding of system-level operations during liquefaction activities. Demonstration testing included system performance determination, constant liquefaction demonstrations, and transient liquefaction demonstrations. The demonstrations showed the operational capabilities of the tube-on-tank system with an integrated cryocooler. Testing met all target liquefaction rates and completed all planned demonstrations of transient operations. Additional testing explored subsurface versus ullage introduction of the gaseous oxygen (GO2) flow stream, as well as demonstrating a novel fiber optic sensor that measured the temperature gradients along the fluid center line within the tank.