Exploration Extravehicular Mobility Unit (xEMU) Hard Upper Torso (HUT) Chamber B Thermal Vacuum Testing Results

NASA's Exploration Extravehicular Mobility Unit (xEMU) is the government reference next-generation space suit design and is engineered to protect astronauts from extreme lunar environmental temperatures. To evaluate the xEMU hardware thermal requirements, the xEMU Testing Team invented, designed, and executed a dual-suit, uncrewed thermal vacuum (TVAC) test at Johnson Space Center's (JSC) Chamber B. This paper details the test methodology, hardware setup, and results from the xEMU Hard Upper Torso (HUT). Two HUTs, one composite HUT and one aluminum HUT, were tested simultaneously in Chamber B with different thermal environments. For the aluminum HUT on the Short xEMU (SxEMU) test article, five thermal profiles were tested during five simulated Extravehicular Activities (EVAs). For the composite HUT on the second xEMU eleven unique thermal profiles were tested, including both cold and hot environmental cases, over the course of five continuous days of testing. The radiative thermal environment was controlled through exposure to liquid-nitrogen shrouds on the chamber walls and through a separate heater cage surrounding each respective test article. The thermal effects of the Exploration Informatics (xINFO) lights and camera on the HUT were also tested. Seventy-two temperature sensors were used to collect data in critical locations in the xEMU HUT assembly. This paper will document the testing results and compare the test data against the xEMU HUT and system-level thermal models for model validation. To conclude, this paper will address knowledge gaps presented by unmanned thermal vacuum testing with regard to the HUT and the current state of HUT thermal testing.