Scientists need to know this before we travel to Mars: How much of the planet's dust can be inhaled?

The idea of landing on Mars has fascinated space enthusiasts for a long time. And while we are still years away from an actual crewed mission to the planet's surface, there is one important aspect that needs to be considered well in advance. When an astronaut is wandering around the dusty, rocky surface of Mars, they will have to inevitably deal with exposure to Martian dust. And a major challenge lies in solving the question: how much exposure is safe?

A report by NASA recommends a limit on the amount of Martian dust that can be inhaled by astronauts. The limit, which might be revised in the future, will serve as a reference for engineers who will design air filters and suit-cleaning systems for astronauts’ safety.

Whether it's the Moon or Mars, dust is a huge problem

The Apollo moonwalkers had a difficult time coping with fine, sharp dust particles on the Moon, according to NASA. They eroded spacesuits, caused instruments to overheat, and caused irritation in the eyes and lungs of the astronauts. While Martian dust is not as sharp as its lunar counterpart, it has a lot of hazardous chemicals like perchlorates, chromium, sulfates, and manganese that can harm the lungs.

These tiny dust particles can stick to an astronaut's suit and equipment electrostatically during extravehicular activity and make their way into Martian habitats, thus necessitating the presence of effective filtration and suit cleaning systems.

How much dust is safe

Shaunna Morrison, a professor in the Department of Earth and Planetary Sciences in the Rutgers School of Arts and Sciences and a member of NASA’s Mars Dust Limit Working Group, worked towards determining the safety limit for dust particles. Based on observations by rovers and landers and some tricky laboratory simulations, Morrison and her group evaluated the hazard limits of Martian dust. 

The group backed up NASA’s recommended limit of 0.1 milligrams of Martian dust per cubic meter of air over the course of 24 hours. These exposure conditions can be survived for up to 30 days. "In practical terms, this gives mission designers a target for how clean the air inside a Mars habitat needs to be, with particular consideration required for when astronauts come back from surface activities carrying dust on suits and equipment – likely the most common source of dust within the habitat," Morrison explained.

Morrison particularly emphasized the long-term effects of exposure to Martian dust. "Very fine dust can get deep into the lungs, where it may cause irritation or inflammation, especially if the exposure is repeated or prolonged," she stated.

The standard set by NASA is not the end of the road. Morrison noted that there is one "important knowledge gap." The dust that astronauts might inhale on Mars may differ in size, chemistry, and other aspects from the soil or rock material studied in Martian meteorites. The report by NASA further explained, "As additional Martian data and toxicological research become available, this standard should be periodically revisited to ensure continued protection of crew health during human exploration of Mars."

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