A NASA spacesuit glove designed for use during spacewalks on the International Space Station is prepared for thermal vacuum testing inside a one-of-a-kind chamber called CITADEL (Cryogenic Ice Testing, Acquisition Development, and Excavation Laboratory) at NASA’s Jet Propulsion Laboratory in Southern California on Nov. 1, 2023.
Part of a NASA spacesuit design called the Extravehicular Mobility Unit, the glove was tested at vacuum and minus 352 degrees Fahrenheit (minus 213 degrees Celsius) — temperatures as frigid as those Artemis III astronauts could experience on the Moon’s South Pole. A team from NASA JPL, NASA’s Johnson Space Center in Houston, and the NASA Engineering and Safety Center have collaborated on testing gloves and boots in CITADEL. Elbow joints are slated for testing next. In addition to spotting vulnerabilities with existing NASA suit designs, the experiments will help the agency prepare criteria for test methods for the next-generation lunar suit — being built by Axiom Space — which NASA astronauts will wear during the Artemis III mission.
A NASA spacesuit glove designed for use during spacewalks on the International Space Station is prepared for thermal vacuum testing inside a one-of-a-kind chamber called CITADEL (Cryogenic Ice Testing, Acquisition Development, and Excavation Laboratory) at NASA’s Jet Propulsion Laboratory in Southern California on Nov. 1, 2023.
Part of a NASA spacesuit design called the Extravehicular Mobility Unit, the glove was tested at vacuum and minus 352 degrees Fahrenheit (minus 213 degrees Celsius) — temperatures as frigid as those Artemis III astronauts could experience on the Moon’s South Pole. A team from NASA JPL, NASA’s Johnson Space Center in Houston, and the NASA Engineering and Safety Center have collaborated on testing gloves and boots in CITADEL. Elbow joints are slated for testing next. In addition to spotting vulnerabilities with existing NASA suit designs, the experiments will help the agency prepare criteria for test methods for the next-generation lunar suit — being built by Axiom Space — which NASA astronauts will wear during the Artemis III mission.
Preparations for Next Moonwalk Simulations Underway (and Underwater)
An astronaut glove designed for International Space Station spacewalks is prepped for testing in a chamber called CITADEL at NASA JPL. Conducted at temperatures as frigid as those Artemis III astronauts will see on the lunar South Pole, the testing supports next-generation spacesuit development.
NASA/JPL-Caltech
Engineers with NASA Johnson and the NASA Engineering and Safety Center ready an astronaut glove for insertion into the main CITADEL chamber at JPL. The team tested the glove in vacuum at minus 352 degrees Fahrenheit (minus 213 degrees Celsius).
NASA/JPL-Caltech
A JPL facility built to support potential robotic spacecraft missions to frozen ocean worlds helps engineers develop safety tests for next-generation spacesuits.
When NASA astronauts return to the Moon under the Artemis campaign and eventually venture farther into the solar system, they will encounter conditions harsher than any humans have experienced before. Ensuring next-generation spacesuits protect astronauts requires new varieties of tests, and a one-of-a-kind chamber called CITADEL (Cryogenic Ice Testing, Acquisition Development, and Excavation Laboratory) at NASA’s Jet Propulsion Laboratory in Southern California is helping.
Built to prepare potential robotic explorers for the frosty, low-pressure conditions on ocean worlds like Jupiter’s frozen moon Europa, CITADEL also can evaluate how spacesuit gloves and boots hold up in extraordinary cold. Spearheaded by the NASA Engineering and Safety Center, a glove testing campaign in CITADEL ran from October 2023 to March 2024. Boot testing, initiated by the Extravehicular Activity and Human Surface Mobility Program at NASA’s Johnson Space Center in Houston, took place from October 2024 to January 2025.
An astronaut boot — part of a NASA lunar spacesuit prototype, the xEMU — is readied for testing in JPL’s CITADEL. A thick aluminum plate stands in for the cold surface of the lunar South Pole, where Artemis III astronauts will confront conditions more extreme than any humans have yet experienced.
NASA/JPL-Caltech
In coming months, the team will adapt CITADEL to test spacesuit elbow joints to evaluate suit fabrics for longevity on the Moon. They’ll incorporate abrasion testing and introduce a simulant for lunar regolith, the loose material that makes up the Moon’s surface, into the chamber for the first time.
“We’ve built space robots at JPL that have gone across the solar system and beyond,” said Danny Green, a mechanical engineer who led the boot testing for JPL. “It’s pretty special to also use our facilities in support of returning astronauts to the Moon.”
Astronauts on the Artemis III mission will explore the Moon’s South Pole, a region of much greater extremes than the equatorial landing sites visited by Apollo-era missions. They’ll spend up to two hours at a time inside craters that may contain ice deposits potentially important to sustaining long-term human presence on the Moon. Called permanently shadowed regions, these intriguing features rank among the coldest locations in the solar system, reaching as low as minus 414 degrees Fahrenheit (minus 248 degrees Celsius). The CITADEL chamber gets close to those temperatures.
Engineers from JPL and NASA Johnson set up a test of the xEMU boot inside CITADEL. Built to prepare potential robotic explorers for conditions on ocean worlds like Jupiter’s moon Europa, the chamber offers unique capabilities that have made it useful for testing spacesuit parts.
NASA/JPL-Caltech
“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,” said Zach Fester, an engineer with the Advanced Suit Team at NASA Johnson and the technical lead for the boot testing.
Keeping Cool
Housed in the same building as JPL’s historic 10-Foot Space Simulator, the CITADEL chamber uses compressed helium to get as low as minus 370 F (minus 223 C) — lower than most cryogenic facilities, which largely rely on liquid nitrogen. At 4 feet (1.2 meters) tall and 5 feet (1.5 meters) in diameter, the chamber is big enough for a person to climb inside.
An engineer collects simulated lunar samples while wearing the Axiom Extravehicular Mobility Unit spacesuit during testing at NASA Johnson in late 2023. Recent testing of existing NASA spacesuit designs in JPL’s CITADEL chamber will ultimately support development of next-generation suits being built by Axiom Space.
Axiom Space
More important, it features four load locks, drawer-like chambers through which test materials are inserted into the main chamber while maintaining a chilled vacuum state. The chamber can take several days to reach test conditions, and opening it to insert new test materials starts the process all over again. The load locks allowed engineers to make quick adjustments during boot and glove tests.
Cryocoolers chill the chamber, and aluminum blocks inside can simulate tools astronauts might grab or the cold lunar surface on which they’d walk. The chamber also features a robotic arm to interact with test materials, plus multiple visible-light and infrared cameras to record operations.
Testing Extremities
The gloves tested in the chamber are the sixth version of a glove NASA began using in the 1980s, part of a spacesuit design called the Extravehicular Mobility Unit. Optimized for spacewalks at the International Space Station, the suit is so intricate it’s essentially a personal spacecraft. Testing in CITADEL at minus 352 F (minus 213 C) showed the legacy glove would not meet thermal requirements in the more challenging environment of the lunar South Pole. Results haven’t yet been fully analyzed from boot testing, which used a lunar surface suit prototype called the Exploration Extravehicular Mobility Unit. NASA’s reference design of an advanced suit architecture, this spacesuit features enhanced fit, mobility, and safety.
In addition to spotting vulnerabilities with existing suits, the CITADEL experiments will help NASA prepare criteria for standardized, repeatable, and inexpensive test methods for the next-generation lunar suit being built by Axiom Space — the Axiom Extravehicular Mobility Unit, which NASA astronauts will wear during the Artemis III mission.
“This test is looking to identify what the limits are: How long can that glove or boot be in that lunar environment?” said Shane McFarland, technology development lead for the Advanced Suit Team at NASA Johnson. “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.”
In the past, astronauts themselves have been part of thermal testing. For gloves, an astronaut inserted a gloved hand into a chilled “glove box,” grabbed a frigid object, and held it until their skin temperature dropped as low as 50 F (10 C). McFarland stressed that such human-in-the-loop testing remains essential to ensuring future spacesuit safety but doesn’t produce the consistent data the team is looking for with the CITADEL testing.
To obtain objective feedback, the CITADEL testing team used a custom-built manikin hand and foot. A system of fluid loops mimicked the flow of warm blood through the appendages, while dozens of temperature and heat flux sensors provided data from inside gloves and boots.
“By using CITADEL and modern manikin technology, we can test design iterations faster and at much lower cost than traditional human-in-the-loop testing,” said Morgan Abney, NASA technical fellow for Environmental Control and Life Support, who conceived the glove testing effort. “Now we can really push the envelope on next-generation suit designs and have confidence we understand the risks. We’re one step closer to landing astronauts back on the Moon.”
Through Artemis, NASA will send astronauts to explore the Moon for scientific discovery, economic benefits, and build the foundation for the first crewed missions to Mars.
Scientists have hypothesized since the 1960s that the Sun is a source of ingredients that form water on the Moon. When a stream of charged particles known as the solar wind smashes into the lunar surface, the idea goes, it triggers a chemical reaction that could make water molecules.
Now, in the most realistic lab simulation of this process yet, NASA-led researchers have confirmed this prediction.
The finding, researchers wrote in a March 17 paper in JGR Planets, has implications for NASA’s Artemis astronaut operations at the Moon’s South Pole. A critical resource for exploration, much of the water on the Moon is thought to be frozen in permanently shadowed regions at the poles.
“The exciting thing here is that with only lunar soil and a basic ingredient from the Sun, which is always spitting out hydrogen, there’s a possibility of creating water,” Li Hsia Yeo, a research scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “That’s incredible to think about,” said Yeo, who led the study.
Solar wind flows constantly from the Sun. It’s made largely of protons, which are nuclei of hydrogen atoms that have lost their electrons. Traveling at more than one million miles per hour, the solar wind bathes the entire solar system. We see evidence of it on Earth when it lights up our sky in auroral light shows.
Computer-processed data of the solar wind from NASA’s STEREO spacecraft. Download here: https://svs.gsfc.nasa.gov/12329
NASA/SwRI/Craig DeForest
Most of the solar particles don’t reach the surface of Earth because our planet has a magnetic shield and an atmosphere to deflect them. But the Moon has no such protection. As computer models and lab experiments have shown, when protons smash into the Moon’s surface, which is made of a dusty and rocky material called regolith, they collide with electrons and recombine to form hydrogen atoms.
Then, the hydrogen atoms can migrate through the lunar surface and bond with the abundant oxygen atoms already present in minerals like silica to form hydroxyl (OH) molecules, a component of water, and water (H2O) molecules themselves.
Scientists have found evidence of both hydroxyl and water molecules in the Moon’s upper surface, just a few millimeters deep. These molecules leave behind a kind of chemical fingerprint — a noticeable dip in a wavy line on a graph that shows how light interacts with the regolith. With the current tools available, though, it is difficult to tell the difference between hydroxyl and water, so scientists use the term “water” to refer to either one or a mix of both molecules.
Many researchers think the solar wind is the main reason the molecules are there, though other sources like micrometeorite impacts could also help by creating heat and triggering chemical reactions.
In 2016, scientists discovered that water is released from the Moon during meteor showers. When a speck of comet debris strikes the moon, it vaporizes on impact, creating a shock wave in the lunar soil. With a sufficiently large impactor, this shock wave can breach the soil’s dry upper layer and release water molecules from a hydrated layer below. NASA’s LADEE spacecraft detected these water molecules as they entered the tenuous lunar atmosphere. Download here: https://svs.gsfc.nasa.gov/20278/
NASA’s Goddard Space Flight Center Conceptual Image Lab
Spacecraft measurements had already hinted that the solar wind is the primary driver of water, or its components, at the lunar surface. One key clue, confirmed by Yeo’s team’s experiment: the Moon’s water-related spectral signal changes over the course of the day.
In some regions, it’s stronger in the cooler morning and fades as the surface heats up, likely because water and hydrogen molecules move around or escape to space. As the surface cools again at night, the signal peaks again. This daily cycle points to an active source — most likely the solar wind—replenishing tiny amounts of water on the Moon each day.
To test whether this is true, Yeo and her colleague, Jason McLain, a research scientist at NASA Goddard, built a custom apparatus to examine Apollo lunar samples. In a first, the apparatus held all experiment components inside: a solar particle beam device, an airless chamber that simulated the Moon’s environment, and a molecule detector. Their invention allowed the researchers to avoid ever taking the sample out of the chamber — as other experiments did — and exposing it to contamination from the water in the air.
“It took a long time and many iterations to design the apparatus components and get them all to fit inside,” said McLain, “but it was worth it, because once we eliminated all possible sources of contamination, we learned that this decades-old idea about the solar wind turns out to be true.”
Using dust from two different samples picked up on the Moon by NASA’s Apollo 17 astronauts in 1972, Yeo and her colleagues first baked the samples to remove any possible water they could have picked up between air-tight storage in NASA’s space-sample curation facility at NASA’s Johnson Space Center in Houston and Goddard’s lab. Then, they used a tiny particle accelerator to bombard the dust with mock solar wind for several days — the equivalent of 80,000 years on the Moon, based on the high dose of the particles used.
They used a detector called a spectrometer to measure how much light the dust molecules reflected, which showed how the samples’ chemical makeup changed over time.
In the end, the team saw a drop in the light signal that bounced to their detector precisely at the point in the infrared region of the electromagnetic spectrum — near 3 microns — where water typically absorbs energy, leaving a telltale signature.
While they can’t conclusively say if their experiment made water molecules, the researchers reported in their study that the shape and width of the dip in the wavy line on their graph suggests that both hydroxyl and water were produced in the lunar samples.
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