By Will Dunham
WASHINGTON, Oct. 28 (Reuters) – Mars is a dusty place. The dust is spread by everyday winds, by whirlwinds called “dust devils” and by large dust storms on local, regional, and global scales. Dust is a factor that must be taken into account in any crewed mission to Mars, and new data from a NASA rover reveal the magnitude of the challenge it can pose.
The NASA Perseverance rover, which operates within and around an area called Jezero Crater, in the northern hemisphere of Mars, since its landing in 2021, detected the finest dust particles ever recorded on Earth’s planetary neighbor. It recorded ultrafine particles about 100 nanometers wide, roughly 500 times thinner than a human hair.
“A smaller particle size does not necessarily make dust more dangerous, but smaller particles have a greater potential to penetrate deeper into the human body and are harder to eliminate by the body,” said planetary scientist Scott VanBommel, of Washington University in St. Louis, a member of the Perseverance science team and the lead author of a study describing the findings in the Proceedings of the National Academy of Sciences.
“Like any substance, toxicity depends on dose and duration. Martian dust contains silica, iron compounds and chlorine compounds, such as perchlorate, which are known to be harmful at sufficiently high doses on Earth,” VanBommel said.
The Perseverance measured dust particles that adhered to the rover’s equipment, including spacesuit materials carried aboard the six-wheeled robotic vehicle, with the aim of observing how they behave in the planet’s harsh environment.
Previous measurements identified Martian dust particles with diameters of up to about 3 micrometers. But Perseverance’s Planetary Instrument for Lithochemistry of X-Rays (PIXL) recorded two even smaller categories. In addition to ultrafine particles, there was a category of fine particles with diameters less than 2.5 micrometers, or 30 times finer than a human hair.
Particles so tiny could be small enough to penetrate an astronaut’s lungs, enter the bloodstream, and potentially cause damage to vital organs. Another concern is that the Martian environment and the dust’s physical properties could degrade, over time, the materials of spacesuits and habitats.
With this in mind, Perseverance is carrying samples of possible spacesuit materials, such as the synthetic fiber Vectran and the protective coating Teflon, each about three-quarters of an inch (20 mm) on a side.
“We have no evidence that the dust has damaged spacesuit materials, only that the materials tended to interact with dust in different ways,” VanBommel said. “Vectran seemed to retain larger dust particles, with a higher prevalence on the lower portion of its weave. The Teflon sample retained less dust, but the retained dust was finer, reflecting differences in how electrostatic properties can cause particles of different sizes to adhere preferentially to each material.”
NASA aims to send astronauts to Mars as early as the 2030s.
“These findings will help guide the design of future life-support systems for crewed Mars missions, including the selection of materials for spacesuits and habitats, as well as effective cleaning methods for submicrometric particles. They also contribute to the guidelines and protocols NASA has established for toxicological risks,” VanBommel said.
NASA has experience with the effects of dust since the Apollo lunar landings, from 1969 to 1972. Lunar dust degraded the outer layers of spacesuits, damaged seals and scratched visors. It may also have been linked to hay fever-like symptoms in some astronauts.
But Martian dust differs from lunar dust.
“On the Moon, dust is generated primarily by surface impacts, including micrometeorites. Without an atmosphere or wind to wear it down, lunar particles remain sharp and angular. Much of the concern about lunar dust stems from its shape, whereas for Martian dust, its chemical composition and particle size are the main concerns,” VanBommel said.
