Dust may not sound like the most dramatic challenge of sending people to Mars, but anyone who studied the Apollo missions knows better. Now NASA’s Perseverance rover has delivered the first on-site measurements of the tiniest Martian dust grains, and the findings could shape the spacesuits, habitats and health rules for future crews.

According to a NASA announcement released October 26, the results are being published Tuesday, October 27, in the Proceedings of the National Academy of Sciences.

A science experiment hiding on the rover

Perseverance’s main job is to search for signs of ancient microbial life in Jezero Crater. But it also carries a few items meant to help prepare for human explorers, including small samples of spacesuit materials.

These swatches, each about three-quarters of an inch (20 millimeters) square, sit on a calibration target for SHERLOC, an instrument on the rover’s robotic arm. Another instrument, PIXL, has its own calibration target that includes a piece of Teflon and a piece of basaltic glass.

Here is the clever part: Teflon contains no elements PIXL can detect directly. So any signal PIXL picks up from the Teflon must be coming from dust sitting on top of it. Over 1,645 Martian days, the team used these targets to study what kind of dust stuck, and how small it got.

How small is small?

Earlier measurements on Mars could resolve dust particles down to about 3 micrometers across. PIXL detected two even smaller categories, NASA said:

  • Fine particles: smaller than 2.5 micrometers. For comparison, a human hair is about 70 micrometers wide.
  • Ultrafine particles: around 100 nanometers, roughly 700 times thinner than a human hair.

On some surfaces, dust averaged about 2 micrometers. On others, particles ranged down to about 100 to 300 nanometers.

“The larger clumps, the Martian dust bunnies, get shaken off over time,” said lead author Scott VanBommel of Washington University in St. Louis. “But the smallest particles stay behind, and those are the ones that pose the greatest challenge for human support systems.”

Static electricity is the glue

The study suggests static electricity determines which particles cling to which materials. Dust grains become charged as they collide in the thin Martian air, and different materials attract grains of different sizes. The finest particles stayed attached through years of driving and drilling.

Organic polymers like Teflon, which are common in the outer layers of spacesuits, readily collected fine dust. But some materials held less dust than others, a finding that could guide choices of suit fabrics and protective coatings.

Why it matters for astronaut health

On Earth, particles smaller than 2.5 micrometers are linked to health problems because they can reach deep into the lungs and enter the bloodstream, NASA noted. Martian dust also contains reactive compounds, including perchlorates that can disrupt thyroid function and reactive iron that can damage cells. Scientists believe the risk depends on how much dust astronauts are exposed to and for how long.

Chemically, the dust matched the iron- and sulfur-rich composition seen by earlier missions, with added signs of phosphorus and calcium sulfate.

Apollo showed what dust can do. Lunar dust scratched visors, degraded outer suit layers, damaged seals, and caused some astronauts to report hay fever-like symptoms. Mars dust is rounder and less abrasive than lunar dust, but it can be stirred up by regional and global dust storms.

Turning data into design

NASA says the measurements could help engineers and flight surgeons refine indoor dust-exposure limits and dust-removal procedures. Ideas already on the table include suitports, which let astronauts climb into a suit attached to the outside of a habitat, and dual-chamber airlocks to keep dust out of living quarters.

The agency is also testing hardware closer to home. In March 2025, an Electrodynamic Dust Shield used electric fields to clear lunar regolith from surfaces on the Moon aboard Firefly Aerospace’s Blue Ghost Mission 1.

The bottom line

Perseverance was sent to look for ancient life, but a few small fabric squares on its deck have quietly answered a very human question: what will Mars dust do to the people who walk on it? The answer is that the tiniest grains are the stickiest, and designers now have real data to plan around.

Image: Jezero crater on Mars, sol 181 of Perseverance mission by NASA/JPL-Caltech/ASU via Wikimedia Commons, Public Domain Mark 1.0