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Travellers to Mars Need to Avoid the Dust

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A Martian dust storm captured by the ESA’s Mars Express. Credit: ESA

NASA and China plan to send astronauts and taikonauts to Mars in the coming decades. As the next step beyond lunar exploration, all major space agencies hope to send crewed missions there at some point. This should come as no surprise since Mars is the most potentially habitable planet in the Solar System beyond Earth. However, the challenges of sending humans to the Red Planet are legion, including the distances involved. Using conventional propulsion, it would take a mission six to nine months to reach Mars, during which time crews will be exposed to microgravity and elevated radiation levels.

In addition, human explorers will face multiple hazards upon arrival. These include the lower gravity (about 38% that of Earth), radiation, and Martian regolith. Much like lunar exploration, scientists are concerned about the long-term health effects of exposure to this fine, toxic dust. According to a recent study led by researchers from the University of Southern California (USC), long-term exposure to Martian dust could lead to various health problems, including chronic respiratory problems, thyroid disease, and more.

The research was led by Justin Wang, a medical student at the Keck School of Medicine of USC and an officer in the US Navy Medical Corps. He was joined by fellow researchers from Keck USC, the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado Boulder, the University of California Los Angeles (UCLA), and the Astromaterials Acquisition and Curation Office at the NASA Johnson Space Center. That paper that describes their findings recently appeared in the journal Geohealth.

Thanks to the Apollo missions, scientists are familiar with the hazards of lunar regolith. Upon returning to Earth, astronauts reported eye irritation, respiratory irritation, and bronchitis, which was attributed to the dust they tracked back into their lunar landers. Today, scientists, medical professionals, and mission planners have similar concerns about Mars. Much like the Moon, Mars' surface is covered in a fine powder of silicate minerals, iron oxides, sulfates, and toxic elements like beryllium, arsenic, and perchlorates.

However, the effects of long-term exposure to this dust are less well-understood. As Wang noted in a CU Boulder press release, the greatest concern is the size of dust particulates, which is estimated to measure 3 micrometers in diameter. "That's smaller than what the mucus in our lungs can expel," he said. "So after we inhale Martian dust, much of it could remain in our lungs and be absorbed into our bloodstream." Moreover, crewed missions to Mars will likely involve up to a year and a half of surface operations.

During this time, astronauts must deal with dust storms, which can periodically grow to encompass the entire planet. As a result, they are likely to track some of this dust back into their habitats, where it could be inhaled. As Brian Hynek, a LASP professor of geology and co-author on the paper, said in a UC Boulder press release:

"You're going to get dust on your spacesuits, and you're going to have to deal with regular dust storms. We really need to characterize this dust so that we know what the hazards are. We think there could be 10 meters of dust sitting on top of the bigger volcanoes. If you tried to land a spacecraft there, you're going to just sink into the dust."

Artist's impression of a potential Mars habitat and other surface elements. Credit: NASA

To address this, Wang and his colleagues consulted data from Martian rovers and meteorites to gain a better understanding of what composes this regolith. Their study is the first comprehensive examination of the chemical composition of Mars regolith and its possible impacts on human health. Interestingly, their results bore some similarities to common health problems on Earth, which included a condition known as silicosis. This condition, caused by inhaling silicates, leads to the buildup of scar tissue in the lungs and respiratory difficulty.

However, the results were less clear when it came to perchlorates, though there is evidence that suggests that exposure to perchlorates can lead to severe anemia due to their effect on thyroid function. In terms of solutions, Wang and his team recommend that prevention is key, and strategies need to be developed long before astronauts are sent to Mars. These include dust filtration, cabin cleaning, and iodine supplements to increase thyroid function. Said Wang:

"This isn't the most dangerous part about going to Mars. But dust is a solvable problem, and it's worth putting in the effort to develop Mars-focused technologies for preventing these health problems in the first place. Prevention is key. We tell everyone to go see their primary care provider to check [their] cholesterol before it gives you a heart attack. The best thing we can do on Mars is make sure the astronauts aren't exposed to dust in the first place."