NASA's upcoming lunar missions promise to be significantly colder than those undertaken during the Apollo program. As astronauts prepare to explore the Moon's permanently shadowed regions at the lunar south pole, the agency is focused on ensuring that they remain comfortable and safe in these extreme conditions.

A dedicated team of engineers at NASA is currently conducting tests on elbow joints within a large cryogenic chamber, which has been specifically designed to evaluate the next-generation spacesuits intended for use on the Moon. This facility, known as the Cryogenic Ice Testing, Acquisition Development, and Excavation Laboratory (CITADEL), was initially established to test robotic components for non-crewed missions targeting the icy moons of our solar system. However, it has now taken on a pivotal role in humanity's long-awaited return to our lunar neighbor.

We want to understand what the risks are for astronauts venturing into the permanently shadowed regions of the Moon, explained Zach Fester, an engineer with the Advanced Suit Team at NASA Johnson Space Center and the technical lead overseeing boot testing. He emphasized the importance of the gloves and boots worn by astronauts, noting that these components frequently come into contact with extremely cold surfaces and tools.

The CITADEL facility is an impressive structure, measuring 4 feet (1.2 meters) in height and 5 feet (1.5 meters) in width. It is located at NASAs Jet Propulsion Laboratory. Unlike most cryogenic facilities that utilize liquid nitrogen, CITADEL employs compressed helium to achieve frigid temperatures as low as -370 degrees Fahrenheit (-223 degrees Celsius). Achieving these temperatures is a meticulous process, often taking several days, and once the chamber is opened, the entire cooling process must restart. To mitigate this issue, CITADEL is equipped with four load locksdrawer-like chambers that allow test materials to be introduced without compromising the vacuum state within the chamber.

In addition, CITADEL features a robotic arm to handle test materials and is outfitted with visible and infrared cameras to document the entire testing process. As part of the simulations intended for the Moon missions, the team will incorporate abrasion testing and lunar regolith-like material into the chamber, along with aluminum blocks to simulate tools that astronauts may encounter.

Historically, NASA has relied on actual astronauts for thermal testing, requiring them to insert their gloved hands into a cooled glove box and hold onto freezing objects until their skin temperature dropped to around 50 degrees Fahrenheit (10 degrees Celsius). Now, however, NASA has developed a custom-built manikin hand and foot for testing inside CITADEL. These manikin extremities are equipped with an intricate system of fluid loops designed to replicate the flow of warm blood through human appendages. Additionally, numerous temperature and heat flux sensors gather data from within the gloves and boots during testing.

The Artemis 3 mission is poised to land astronauts on the lunar surface for the first time since the Apollo era. Unlike the Apollo missions, which focused on the Moon's equatorial regions, the Artemis crews are set to explore the lunar south pole. This area is of significant scientific interest, as it may contain deposits of water ice in regions that are perpetually shadowed from sunlight. However, this terrain also poses extreme challenges, characterized by harsh temperatures and areas that rarely experience sunlight. According to NASA, astronauts could spend up to two hours at a time in craters believed to harbor ice deposits, where temperatures can plummet to a bone-chilling -414 degrees Fahrenheit (-248 degrees Celsius).

In preparation for these daunting conditions, astronauts will don new, cutting-edge spacesuits. In 2022, NASA enlisted Axiom Space to create the first moonwalking spacesuits since those used during the Apollo missions. Axiom subsequently introduced the AxEMU, short for Axiom Extravehicular Mobility Unit. This modern suit builds on the legacy of the Apollo designs while integrating advanced technology that enhances astronaut mobility and offers better protection against the unique challenges of the lunar environment. Notably, Axiom Space collaborated with the renowned fashion house Prada to leverage their expertise in design and materials, ensuring that the astronauts not only function well but also look appealing in their lunar attire.

Ongoing evaluations at CITADEL aim to help NASA establish criteria for the next-generation AxEMU spacesuits. Currently, the gloves being tested in the facility are the sixth iteration of a design first introduced in the 1980s and are part of the Extravehicular Mobility Unit utilized by astronauts aboard the International Space Station during spacewalks. Early results from CITADEL indicate that these gloves may not meet the thermal requirements needed for the lunar south pole. Meanwhile, the analysis of the boot testing outcomes is still pending.

Shane McFarland, the technology development lead for NASA's Advanced Suit Team, stated, This test is focused on identifying the limits: How long can the glove or boot withstand the lunar environment? Our goal is to quantify the capability gap of current hardware to provide useful data to the Artemis suit vendor, and to develop this unique testing capacity for future hardware designs.

The Artemis 3 mission is scheduled to launch in 2027, embarking on a journey to chart previously unexplored areas of the Moon. With ongoing advancements in testing and suit design, NASA's hope is that its astronauts will be well-equipped to stay warm in the dark and frigid conditions of the lunar south pole.