The finest dust on Mars sticks to spacesuit materials and stays there, according to new measurements from NASA's Perseverance rover. Over 1,645 Martian days of driving and drilling, larger clumps of dust fell off small spacesuit-fabric samples carried on the rover, while particles far smaller than a human hair remained attached, NASA reported on Oct. 26.

The rover's PIXL instrument spotted fine particles under 2.5 micrometers and ultrafine particles around 100 nanometers wide. Earlier Mars missions could only resolve dust down to about 3 micrometers, so the new readings reach well below the sizes earlier surface instruments could see.

That matters for the first people who go to Mars. Particles that small can slip through seals, wear down fabric and, if breathed in, reach deep into the lungs. The results, published Oct. 27 in the Proceedings of the National Academy of Sciences, give suit and habitat engineers their first direct look at what they will be up against.

Five Fabric Squares Riding on a Rover

Perseverance carries five spacesuit-material swatches, each about three-quarters of an inch square, on the calibration target of its SHERLOC instrument. According to NASA's Jet Propulsion Laboratory, they include polycarbonate used in helmet visors, Vectran used in cut-resistant glove palms, two types of Teflon and a layered Ortho-Fabric.

The new study focused on the Teflon and Vectran samples, along with a Teflon and basaltic glass target belonging to PIXL itself. Teflon contains no elements PIXL can detect, so any signal from it had to come from dust settled on top.

Lead author Scott VanBommel, a Perseverance scientist at Washington University in St. Louis, described the pattern in NASA's release: "The larger clumps, the Martian dust bunnies, get shaken off over time." The smallest grains, he said, stayed behind, and those pose the greatest challenge for life-support systems.

Particles on the PIXL Teflon target and the Vectran swatch averaged about 2 micrometers, while those on the basaltic glass and the SHERLOC Teflon swatch went down to about 100 to 300 nanometers. Different materials held onto different particle sizes.

Static Charge and a Chemistry Problem

NASA said static electricity appears to determine which dust sizes stick to which surface. Dust grains pick up an electric charge as they collide in the thin Martian air, and that charge can bind them tightly to suit materials. The study points to static charge as the likely mechanism, but it has not been directly measured on the swatches.

The dust chemistry adds to the concern — NASA described it as rich in sulfur, chlorine, and iron, enriched in phosphorus, with signs of calcium sulfate. Martian dust contains perchlorates, salts that can disrupt thyroid function, and reactive iron that can damage cells. Mars dust is less jagged than Moon dust because wind has rounded the grains over time.

On Earth, the Environmental Protection Agency defines PM2.5 particles as "fine inhalable particles, with diameters that are generally 2.5 micrometers and smaller." Those are the same size class as wildfire smoke and vehicle exhaust, which are linked to heart and lung disease. NASA notes that ultrafine particles can even travel from the nose toward the brain along the olfactory nerve, though actual risk depends on how much dust a person is exposed to and for how long.

Lessons From Apollo and the Moon

Dust problems are not new — on the Apollo missions, lunar dust scratched visors, wore down outer suit layers, damaged seals and gave some astronauts hay-fever-like symptoms. Apollo 17 geologist Harrison Schmitt later described congestion he called lunar dust hay fever, which cleared the next day.

NASA engineers have long worried that abrasive particles can make suit fabrics "fray and tear, allowing a spacesuit to leak both heat and air," as Johnson Space Center planetary scientist Marc Fries told JPL in 2025. The new data show that Martian dust may cause less scraping than Moon dust but cling just as stubbornly.

NASA is already testing countermeasures for Artemis Moon missions. An Electrodynamic Dust Shield was tested on the Moon aboard Firefly's Blue Ghost lander in 2025, and Johnson Space Center is testing suit parts and a handheld electrostatic dust tool. The Mars results suggest similar static-based cleaning methods may be needed there.

Exposure Limits and Suit Designs Ahead

NASA's Office of the Chief Health and Medical Officer has drafted a proposed limit for Martian dust inside crew habitats, holding particles smaller than 10 micrometers below a 24-hour average of 0.1 milligram per cubic meter for missions up to 30 days, according to a NASA working-group summary. The new size data could sharpen that standard.

The study has limits. The swatches are tiny, sit on a rover rather than a moving astronaut, and experienced only the dust that drifted or was kicked up around Perseverance in Jezero Crater. Conditions elsewhere on Mars, or during a planet-wide dust storm, could differ. Health effects were inferred from the dust's size and chemistry, not tested on living tissue.

For engineers, the practical lessons are clear enough. Airlocks, suitports that keep suits outside the habitat, electrostatic cleaning and materials chosen to shed fine grains will likely matter more than simple brushing. Perseverance continues to collect data, and future analyses of the other swatches could show which materials hold up best.

The bottom line: Mars dust finer than smoke particles has clung to spacesuit samples for 1,645 Martian days, apparently held by static charge. It is not yet a proven health threat, but it gives NASA concrete numbers for designing suits and habitats before crews arrive.

What Readers Want to Know

What did Perseverance find? Fine and ultrafine Mars dust, down to about 100 nanometers, stuck to Teflon and Vectran spacesuit samples for 1,645 Martian days.

Why does the dust stay stuck? NASA says static electricity appears to hold the finest grains in place, though the mechanism has not been directly measured.

Is Mars dust dangerous to breathe? Possibly. It is small enough to reach deep into lungs and contains perchlorates and reactive iron, but risk depends on dose and exposure time.

How is Mars dust different from Moon dust? Mars grains are rounder and less abrasive because of wind, but they appear to cling to materials just as stubbornly.

What is NASA doing about it? It is testing electrostatic dust tools for Artemis and drafting exposure limits for Martian dust inside habitats.

Are 1,645 Martian days the same as Earth days? No. A Martian day, or sol, is about 40 minutes longer than an Earth day.