NASA's Perseverance rover has spent 1,645 Martian days analyzing the fine and ultrafine dust particles that cling to samples of spacesuit materials carried aboard the vehicle. The study, to be published Tuesday, Oct. 27, in the Proceedings of the National Academy of Sciences, reveals that some of these particles are small enough to penetrate the lungs and enter the bloodstream, a finding with direct implications for the health of future human crews on Mars.

Martian dust has long been considered one of the major challenges of human exploration of the Red Planet. Unlike the Moon, where the regolith is abrasive but inert, Martian dust is fine, pervasive and chemically reactive, and it readily settles on equipment, suits and surfaces. Quantitative data, however, were lacking on the size distribution of the particles that actually adhere to spacesuit fabrics under real Martian surface conditions.

To obtain them, the team flew spacesuit material samples on Perseverance, exposing them to the Martian environment and monitoring the dust load they accumulated over more than four Earth years of operations. The analysis characterized both fine and ultrafine particles, precisely those with deep respiratory penetration capacity.

The results provide the first direct measure of dust exposure on the Martian surface and will inform the design of filtration systems, seals and cleaning protocols for crewed missions. NASA expects these measurements to be integrated into the engineering requirements for future suits and habitats, though questions remain about the chronic effects of exposure and about how these particles behave once inhaled.