Liquid nitrogen could keep lunar suits free of lunar dust

Pesky moon 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 to keeping spacesuits dust-free, using pressurized liquid nitrogen to literally blow the dust off surfaces.

During testing, the research team found that a syringe full of liquid nitrogen could remove an average of 98% of the dust stuck to the fabric when used in a vacuum to simulate an airlock. The spray resulted in minimal damage to the space suits worn by simulated astronauts—Barbie dolls in Moon suits—as a result of the treatment. The research was published last month Acta Astronautica.

At the same time, the team found that over the course of the 233 total treatment cycles on 26 spacesuit samples, the liquid nitrogen spray resulted in little degradation of 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 measures essential for lunar missions,” the researchers wrote in their study. “Cryogenic liquid sprays are a newly developed, simple and practical concept for dust suppression in a lunar environment.”

Astronauts on the Apollo missions to the moon used a brush in an attempt to remove moon dust from their suits, but this method wore down the fabric due to the constant rubbing and coarse moon dust.

“Moon dust is electrostatically charged, abrasive and gets everywhere, making it a very difficult substance to deal with,” said Ian Wells of a Washington State University press release. Wells is the first author on the paper and a student at Washington State University’s School of Mechanical and Materials Engineering. “You end up with a fine layer of dust that, at a minimum, just covers everything.”

The liquid nitrogen spray forgoes the use of physical abrasion in favor of the Leidenfrost effect, most commonly seen when a bubble of cold water dances on top of a hot frying pan, as it is insulated from the hot surface by a layer of steam beneath it. Wells and his colleagues say the spray works in a similar way; the cold liquid nitrogen bubbles up onto the warmer space suit and envelops the dust particles before floating off the surface of the fabric.

Tthe scientists cleaned the spacesuits with sweeping motions using liquid nitrogen spray (see middle image above), which was an effective method for removing the simulated dust. ONEafter spot cleaningon the other hand, the suits seemed somewhat dirtier (see the image on the right above), then we reached Wells for clarification. He said that itIt is likely that certain sizes of particles were removed from the suit while others were left behind, making the suit look dirtier. Wells also suggested that spot treating the suit could kick up dust that had settled after the first swipe.

Moon dust is an incredibly fine substance, but it’s also incredibly sharp – it can actually create small tears in spacesuits and boots and even cause health problems. Apollo 17 astronaut Harrison Schmitt referred to “moon hay fever,” where moon dust sticks to the lungs and causes inflammation and congestion. Dust particles 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 remain suspended longer only to be inhaled by an unsuspecting astronaut. This is why effective spacesuit cleaning is so important.

“(Moon dust) posed many problems that affected the missions as well as the astronauts when they returned home,” Wells said in the news release.

The scientists obviously don’t know how this spray would work inside a lunar lander parked on the moon, where gravity is about 16.6% that of Earth. Also, this purification technology would require syringes and containers designed for space travel, and missions that would have to include additional shipments of liquid nitrogen. With all that said, the advantages seem to outweigh the disadvantages, making the liquid nitrogen purification 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 lands on the moon’s south pole no earlier than 2025. As the Artemis program ushers in a new era of lunar exploration—where humans will spend more time than ever on the surface—an effective method of cleaning spacesuits is one of the details that agencies must pay attention to in order to create a seamless human foothold on the moon.

This post was updated to include Wells’ clarification on why the spot clean job looks less clean than the sweep job.

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