The Moon, an ashen Sahara marked with impact craters. As we look to the skies and observe the bright face of this celestial body, we marvel at the feats of engineering and perseverance that landed the first humans on its surface.
Images of astronauts fumbling around as they struggle to function in lunar gravity sometimes resemble that of children playing in a sandpit, serving as evidence of success in Apollo 11’s primary objective: perform a crewed lunar landing and return to Earth. However, the face of the Moon is no playground and certainly not as innocuous as a child’s sandbox. In fact, it is a deceptive mixture that is about as harmless as pulverized fiberglass.
Lunar dust is a statically-charged, abrasive menace. These particles are known to scratch lenses, tear through space suits, obstruct mechanisms and, horribly enough, shred people’s lungs. This “lunar hay-fever” was experienced by several of NASA’s Apollo astronauts, returning to Earth with runny noses, congestion, or a bad cough. While the full range of biological damage is unclear, studies have shown that inhaling lunar dust particles can destroy lung and brain cells after long term exposure. Though we achieved the journey to the Moon, we have yet to develop the means to have a sustained presence on the surface of our satellite.
Although the Moon’s terrestrial conditions make long-term lunar exploration an ambitious undertaking, it is a hurdle that NASA is determined to jump. Earlier this year, they announced their BIG Idea Challenge titled “Dust Mitigation Technologies for Lunar Applications,” inviting graduate and undergraduate students to help solve this very issue.
Around the launch of the 2021 BIG Idea Challenge, members at Washington State University’s Hydrogen Properties for Energy Research (HYPER) Lab made a compelling observation. After pouring excess liquid nitrogen on the floor of the facility after conducting experiments, students noticed a lack of dust and grime where the cryogenic liquid pooled, beaded up, and rolled away before boiling off. Ian Wells, a sophomore at the time and member of the lab’s introductory CORE team, realized that liquid nitrogen may just be the solution to NASA’s lunar dust problems.
In August of 2020, Wells left his team to focus on writing his proposal. The Leidenfrost effect, a phenomenon observed in the lab when nitrogen was poured on the floor, describes how a liquid that touches a hot surface will glide over its own vapor before fully evaporating. Most importantly, this effect’s profound job of picking up any particles in its wake served as the genesis for a dust mitigation concept. With help from CORE team’s Lauren Reising, Camden Butikofer, and Nathaniel Swets, the BIG Idea research proposal was successfully submitted in December of 2020.
Out of the 55 submitted and the seven approved by NASA, Washington State University’s “Leidenfrost Dusting as a Novel Tool for Lunar Dust Mitigation” proposal was declared a finalist. Thus, the HYPER-Borea team was born. Ian Wells, along with Reising, Butikofer, and Swets were a rarity: not only the first unit in the lab primarily composed and led by sophomores, but the youngest team to receive significant research funding on their first go.
Borea recruited graduate students Gregory Wallace, who is working towards his Masters of Science in mechanical engineering and Stasia Kulsa, who has received her bachelors in mechanical engineering and is working towards her masters in flute performance, to help advise the novice group.
While Wallace got to work on a CFD, an animated numerical model displaying a droplet of nitrogen’s properties under different gravitational restraints, the rest of Borea searched for an adequate replacement to simulate moon dust. John Bussey, an undergraduate research assistant at a materials lab on campus, offered ash from Mount St. Helens due to its similar composition to lunar regolith. And so, testing began.
Borea began by applying the ash to a sheet of kevlar nomex weave, similar to that of a spacesuit, and massing it to determine the amount of adhered dust. They then used a hand-held cryotherapy bottle sprayer to shower the contaminated fabric, resulting in a whopping 95% dust removal. Though the results appeared to be promising on Earth, the team needed to prove that the theory could hold-up on the Moon. After six months of troubleshooting, Wallace’s computational fluid dynamics software proved that the Leidenfrost effect does, in fact, apply in lunar gravity. Still, there was still a deciding question: will this effect still operate without an atmosphere?
It was vital for the Borea team to simulate a zero-atmospheric environment, as changes in pressure can significantly change how liquids boil, and their concept relied on boiling fluid. They ultimately settled on a vacuum chamber, and by applying the same technique as in their original test, produced a 98% adhered dust removal efficiency. Spacesuits, however, are not two dimensional. They are complex garments with various folds and creases that are prone to trap dust. Luckily, Stasia Kulsa possessed just the tools needed to settle this issue: a sewing needle and thread.
Kulsa, using a doll as a model and her handy tailoring skills, developed a 1/6th scale astronaut suit using the kevlar nomex material. This doll, aptly named “Rosie” after the cultural icon Rosie the Riveter, became Borea’s final test subject. After massing the spacesuit for adhered dust, Rosie was placed in the vacuum chamber to embark on her final mission. A spray bar system inside the chamber allowed for 360 degree coverage, simulating the team’s proposed usage. She was then spot cleaned with the hand-held sprayer before being massed once more, resulting in yet another successful outcome.
Borea has come a long way since the beginning of their journey. Although research was demanding at times, the team did not forget to have fun. Whether it was the party they hosted for the cryogun celebrating its first day of testing, or their field trips riding through car washes to examine the effectiveness of different types of nozzles and spray bars, they were sure to make memories that would not soon be forgotten. Opportunities like theirs are rare, and they are grateful for the recognition.
“I definitely learned a lot about managing projects and managing people. As well as how to bring a team together,” said Borea team lead, Ian Wells. “I am just proud of where we are going.”
Long-term Moon habitation is a challenging goal, but establishing an effective method to mitigate the difficulties that lunar dust presents is a huge step in the right direction. After nearly a year of research and over 600 experiments, HYPER-Borea is proud to announce their success in the competition, earning NASA’s Artemis Award and best technical paper.
Be sure to check out NASA’s press release here.
Watch their testing procedure video here.
Watch their research presentation video here.