Robotics technologist Brendan Chamberlain-Simon, left, of NASA's Jet Propulsion Laboratory and spacesuit engineer Zach Fester of the agency's Johnson Space Center adjust a thermal vacuum chamber called CITADEL at JPL on Nov. 12, 2024, before testing an astronaut boot inside the chamber.

Built to prepare potential robotic explorers for the frosty, low-pressure conditions on ocean worlds like Jupiter's frozen moon Europa, CITADEL (Cryogenic Ice Testing, Acquisition Development, and Excavation Laboratory) has also proven key to evaluating how astronaut gloves and boots hold up in extraordinary cold. It can reach temperatures as low as low as minus 370 degrees Fahrenheit (minus 223 degrees Celsius), approximating extreme conditions Artemis III astronauts will confront in permanently shadowed regions of the lunar South Pole.

The boot testing was initiated by the Extravehicular Activity and Human Surface Mobility Program at NASA Johnson and took place from October 2024 to January 2025. The boot is part of a NASA spacesuit called the Exploration Extravehicular Mobility Unit, or xEMU.

Test results haven't yet been fully analyzed. In addition to spotting vulnerabilities with existing suits, the experiments are intended to help NASA develop this unique test capability and prepare criteria for standardized, repeatable, and inexpensive test methods for the next-generation lunar suit being built by Axiom Space.