Pesky lunar dust is an annoying obstacle for astronauts landing on the Moon—it sticks to pretty much everything. New research from Washington State University may have cracked the code for keeping space suits dust-free, in which pressurized liquid nitrogen was used to literally blow the dust from surfaces.
During testing, the research team found that a sprayer full of liquid nitrogen could remove an average 98% of the dust stuck to fabric when used in a vacuum to simulate an airlock. The spray resulted in minimal damage to the spacesuits worn by simulated astronauts—Barbie dolls in Moon suits—as a result of the treatment. The research was published last month in Acta Astronautica.
At the same time, the team found that over the course the 233 total cycles of treatments on 26 spacesuit samples, the liquid nitrogen spray resulted in little degradation to the spacesuit fabric. To simulate lunar dust, the researcher used volcanic ash from Mount St. Helens, and also materials from Offplanet Research and Exolith Labs.
Lunar dust “degrades human health and equipment making mitigation paramount for lunar missions,” the scientists wrote in their study. “Cryogenic liquid sprays are a recently developed, simple, and convenient concept for dust mitigation in a lunar environment.”
Astronauts on the Apollo missions to the Moon used a brush in an attempt to remove lunar dust from their suits, but this method wore down the fabric due to the constant rubbing and rough Moon dust.
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“Moon dust is electrostatically charged, abrasive and gets everywhere, making it a very difficult substance to deal with,” said Ian Wells in a Washington State University press release. Wells is the first author on the paper and a student in Washington State University’s School of Mechanical and Materials Engineering. “You end up with a fine layer of dust as a minimum just covering everything.”
The liquid nitrogen spray forgoes the use of physical abrasion in favor of the Leidenfrost effect, which is most commonly seen when a bubble of cold water dances atop a hot frying pan, as it’s insulated from the hot surface by a layer of vapor underneath it. Wells and his colleagues say that the spray works in a similar fashion; the cold liquid nitrogen beads up on the warmer spacesuit, enveloping the dust particles before floating off the surface of the fabric.
The researchers cleaned the spacesuits with sweeping motions using the liquid nitrogen spray (see center image above), which was an effective method of removing the simulated dust. After spot cleaning, however, the suits appeared somewhat dirtier (see right image above), so we reached to Wells for clarification. He said that it’s likely that certain sized particles were successfully removed from the suit, while others were left behind, making the suit look dirtier. Wells also suggested that spot treating the suit might kick up dust that had settled after the initial sweep.
Moon dust is a incredibly fine substance, but it is also incredibly sharp—it can actually create small tears in space suits and boots and even cause health issues. Apollo 17 astronaut Harrison Schmitt referred to “lunar hay fever,” in which Moon dust clings to lungs and causes inflammation and congestion. Particles of dust can hitch a ride into habitats and modules on spacesuits, and since the Moon’s gravity is so much less than Earth’s, these particles will stay suspended for longer only to be inhaled by an unsuspecting astronaut. This is why effective spacesuit cleaning is so important.
“[Lunar dust] posed a lot of problems that affected the missions as well as the astronauts once they returned home,” Wells said in the press release.
The researchers obviously don’t know how this spray will function inside a lunar lander parked on the Moon, where gravity is about 16.6% that of Earth’s. Also, this cleaning technology would require sprayers and canisters engineered for spaceflight, and missions having to include extra shipments of liquid nitrogen. With all that said, the pros appear to outweigh the cons, making the liquid nitrogen cleaning technique a worthwhile investment for future missions to the Moon.
NASA is sending more astronauts to the Moon as part of the Artemis program, with two crew members landing on the lunar south pole no earlier than 2025. As the Artemis program ushers in a new era of Moon exploration—where humans will be spending more time than ever on the surface—an effective method for cleaning space suits is one of the details that agencies need to account for in order to foster a seamless foothold for humanity on the Moon.
This post was updated to included Wells’s clarification as to why the spot cleaning effort looks less clean than the sweep cleaning effort.