NASA’s upcoming missions to the Moon are set to be a lot more chilly than the Apollo program, and the agency is working to figure out how to keep its astronauts snug when visiting the permanently shadowed regions of the lunar south pole.
A team of NASA engineers is preparing to test elbow joints in a large cryogenic chamber to evaluate the fabric of the next-generation spacesuits designed to be worn by astronauts on the Moon. The Cryogenic Ice Testing, Acquisition Development, and Excavation Laboratory, or CITADEL for short, was built to test robot parts for non-crewed missions launching to places like the icy moons of the solar system. CITADEL is now being used for humanity’s long-anticipated return to the Moon.
“We want to understand what the risk is to astronauts going into permanently shadowed regions, and gloves and boots are key because they make prolonged contact with cold surfaces and tools,” Zach Fester, an engineer with the Advanced Suit Team at NASA Johnson and the technical lead for the boot testing, said in a statement.
The 4 feet (1.2 meters) tall and 5 feet (1.5 meters) wide CITADEL is housed at NASA’s Jet Propulsion Laboratory. While most cryogenic facilities use liquid nitrogen to cool an object, CITADEL uses compressed helium to reach temperatures as low as -370 Fahrenheit (-223 Celsuis). The chamber takes several days to reach the desired temperatures, and opening it can restart the entire process. To avoid that the CITADEL is equipped with four load locks, drawer-like chambers through which test materials can be inserted while maintaining its chilled vacuum state.
CITADEL also has a robotic arm to grab test materials, as well as visible and infrared light cameras to capture the entire testing process. For simulations of the Moon missions, the team will also add abrasion testing and lunar regolith-like material to the chamber, and aluminum blocks to simulate tools that the astronauts might grab.
In the past, NASA would use its actual astronauts for thermal testing, forcing them to insert their gloved hands inside a chilled glove box, grab a frigid object and hold onto it until their skin temperatures dropped as low as 50 degrees Fahrenheit (10 degrees Celsius). The space agency now uses a custom-built manikin hand and foot for testing inside CITADEL. The manikin’s extremities are equipped with a system of fluid loops to mimic the flow of warm blood through the appendages, and dozens of temperature and heat flux sensors collect data from inside the gloves and boots.
NASA’s Artemis 3 mission is set to land astronauts on the lunar surface for the first time since the days of Apollo. While Apollo astronauts landed near the equator on the near side of the Moon, the Artemis crews will explore the lunar south pole. The Moon’s south pole is of great interest to scientists as it may hold water ice in permanently shadowed regions, but it does present a harsh environment due to extreme temperatures and areas where the Sun’s light doesn’t reach. The Artemis astronauts will spend somewhere around two hours at a time inside craters that may contain ice deposits, where temperatures can reach a chilling -414 degrees Fahrenheit (-248 degrees Celsius), according to NASA.
Astronauts returning to the Moon will don new, fashion-forward spacesuits. In 2022, NASA tasked Axiom Space with developing the first moonwalking spacesuits since the Apollo missions. The company then announced the AxEMU, short for Axiom Extravehicular Mobility Unit, which was built on the legacy of the Apollo spacesuits while incorporating new technology to allow astronauts more mobility and better protection against the lunar environment. Axiom Space partnered with Prada to draw on the brand’s expertise in design and materiasl, while also trying to provide an aesthetically pleasing look for the astronauts on the Moon.
The ongoing tests in CITADEL will help NASA prepare criteria for its next-generation AxEMU spacesuits. Meanwhile, the gloves being tested in the chamber are the sixth version of a glove NASA began using in the 1980s, and a part of the Extravehicular Mobility Unit that the astronauts on board the International Space Station wear to carry out spacewalks. The gloves have so far performed poorly in CITADEL, proving that they would not meet the thermal requirements of the lunar south pole, according to NASA. Results from the testing on the boots haven’t been fully analyzed yet.
Shane McFarland, technology development lead for the Advanced Suit Team at NASA Johnson, said in a statement, “This test is looking to identify what the limits are: How long can that glove or boot be in that lunar environment? We want to quantify what our capability gap is for the current hardware so we can give that information to the Artemis suit vendor, and we also want to develop this unique test capability to assess future hardware designs.”
NASA’s Artemis 3 mission is set to launch in 2027, sending astronauts on a journey across previously unexplored areas of the Moon. Hopefully the astronauts can keep warm in the dark and chilly lunar south pole.