Moon dust, the fine, fluffy powder covering the moon, is the stuff of imagination, the subject of scientific inquiry, and potential building block for lunar colonies.
It is also a menace to exploration.
As astronauts walk across the moon, land spacecraft on its surface, drive lunar rovers around, or complete other astronaut tasks, they kick up the dust, and that is a problem because it can cause premature wear on mechanical parts, damage to seals, and may pose a health risk for the people breathing it in. Additionally, it has qualities that make it cling to nearly every available surface.
"The sun is shining directly on these particles and giving them an electric charge," says third-year Caltech undergraduate student Luis Pabon. "This causes it to stick to the astronaut's suit or to any sensors or cameras that you put out on the moon."
NASA has known about this issue since the Apollo 11 astronauts dealt with dust during their landing in 1969. Last year, the agency's Breakthrough, Innovative, and Game-changing (BIG) Idea Challenge asked university teams to invent solutions to the pesky dust problem. Now NASA has named a group of Caltech undergraduates as one of seven BIG Idea Challenge finalists for their idea to combat dust on boots from entering into the astronauts' habitat or craft.
The Caltech team's invention, named Habitat Orientable & Modular Electrodynamic Shield (HOMES), tackles the problem of moon dust entering a potential lunar habitat and wreaking havoc within. HOMES is a modular system of square tiles about the thickness of an iPhone that can be arranged into a flat surface. The tiles make up an electrodynamic dust shielding (EDS) system. Wires embedded within the tiles create an electrical field that extends like a forcefield across the tiles' surface, explains third-year student and team member Isabella Dulá. The dust particles carry an electrical charge given to them by rays from the sun, so the electrical field on the tiles repels them. Thus, by varying or alternating the current in the wires, or by changing the orientation of the tiles, a user can tailor the electric field to move dust in a controlled way.
"HOMES could be on the floor of a changing room in an airlock, and any dust that falls to the floor can then be transported to a singular zone because we can orient the panels to move the dust in a specified direction," says second-year Caltech undergraduate Malcolm Tisdale, one of the leaders of the team, which is mentored by Bren Professor of Aerospace Soon-Jo Chung. "That would allow astronauts to much more easily clean a pile of dust instead of it being spread over the entire room."
The students' involvement was set in motion last fall when Tisdale and Pabon approached Chung to restart a campus chapter of the American Institute of Aeronautics and Astronautics (AIAA), a professional organization for the field of aerospace engineering. Pabon, a HOMES project lead and chair of the revived Caltech AIAA, says a project promptly fell into their laps when NASA announced the BIG Idea Challenge, and a group of undergraduates coalesced into a team. They had no previous experience in proposal writing and had to navigate a remote-only collaboration because of the COVID-19 pandemic, which led to hours-long Saturday "work-a-thons" over Zoom.
"Our first idea was a folding, origami-like electrostatic doormat that would take dust off astronauts' boots since most of the dust is going to be condensed down to their boots and lower legs," Tisdale says. Soon, though, the students realized that a surface that did not need to fold would be more efficient and adaptable. "They came up with very creative, innovative idea focusing on modularity," Chung says. "So, it's something like space Lego blocks or Tinker Toys. You can bring these types of 'simple' blocks or tiles and make something bigger or more complex." Chung aptly recalls the quote by Leonardo da Vinci, "Simplicity is the ultimate sophistication."
The students say access to mentors at Caltech and the Jet Propulsion Laboratory, which Caltech manages for NASA, was invaluable in guiding the project. Those experts encouraged the team to focus on the core function required and scrap any frills or embellishment. The mentors include JPL's Jason Kastner (PhD '03) and Manan Arya (MS '12, PhD '16), and former JPL director Charles Elachi (MS '69, PhD '71), Caltech professor of electrical engineering and planetary science, emeritus.
The mentors helped the students focus on proven materials and systems. For example, the tiles are made of aluminum oxide, a ceramic proven to be durable under space conditions. Because EDS systems have previously been used in experiments aboard the International Space Station, NASA rates it at as having a high "technological-readiness level," meaning there is high confidence and evidence that the system works in space.
In addition, the team also had the opportunity to interview astronaut and Caltech alumnus Robert Behnken (MS '93, PhD '97), who offered insights into the engineering standards used by NASA, for example, and practical advice on how astronauts might work with a system like HOMES while on a mission.
"He gave really good metrics about how you would handle these things and the reduced mobility you have in a spacesuit," Dulá says. "Another piece of advice he suggested: instead of having astronauts assemble this while in spacesuits, most likely it would be assembled in an airlock." That way, she says, astronauts would not have to wear bulky suits while putting together the tiles. Once assembly is complete, they could take the HOMES tiles outside and place them wherever they are needed.
Armed with up to $180,000 in funding from NASA, the HOMES team now joins six other finalist teams in building a prototype version of their technology. Dulá notes that seven Caltech team members are located in or near Pasadena and are adhering to campus and county regulations in determining possible physical workspaces where the students can safely collaborate in person during the pandemic. Those seven will form a "ground crew" while the others collaborate remotely as a "support crew." If HOMES passes a mid-project review with NASA in May, the team will compete against the other finalists in Las Vegas this fall, assuming such an in-person gathering is safe by then.
Whatever happens next, Chung marvels at the fact that a group composed solely of undergraduates has thrived in a competition against many other university teams that include PhD students. "[JPL chief technologist] Fred Hadaegh opened the proposal and said, 'Did the undergraduate students write this proposal?'" Chung recalls. "This is amazing because they essentially worked together for only a month or two to come up with one of the most compelling dust mitigation ideas selected by NASA for development."
The HOMES team members include: Malcolm Tisdale, BS '23, Mechanical Engineering; Luis Pabon, BS '22, Mechanical Engineering; Isabella Dulá, BS '22, Mechanical Engineering; Polina Verkhovodova, BS '22, Mechanical Engineering; Leah Soldner, BS '24, Mechanical Engineering; Tanmay Gupta, BS '24, Physics; Nathan Ng, BS '24, Mechanical Engineering; Athena Kolli, BS '24, Mechanical Engineering; Kemal Pulungan, BS '25, Mechanical Engineering; Jules Pénot, BS '24, Mechanical Engineering; Calle Junker, BS '23, Mechanical Engineering; Kaila Coimbra, BS '23, Mechanical Engineering; Rithvik Musuku, BS '24, Mechanical Engineering; Parul Singh, BS '24, Mechanical Engineering