As Apollo astronauts trundled and trod awkwardly across the desolate lunar landscape, an insidious menace scuffed up their spacesuits. Moondust. Fine as talcum powder, sharp as glass and seemingly everywhere, these super-fine particles coated the astronauts like soot and permeated their crew cabin, where it became more than a mere nuisance. Not only did it interfere with their equipment, it irritated their nostrils and eyes, giving some a mild allergic reaction.
Nevertheless, between 1969 and 1972, Apollo astronauts brought back nearly 385 kilograms of lunar rock, pebbles and powder back to earth. Moondust deserved further study.
Today, NASA deems interplanetary dust and dirt — also known as regolith — one of the greatest risks to long-term space settlements. On Mars, it’s toxic and magnetic. On the Moon, it wears away at multi-million-dollar instruments and lodges into the slightest crevasses, weakening seals on pressure suits and causing hardware to malfunction. But for all its difficulties, regolith holds astronomical potential, too. It’s considered key to sustainable space exploration and will likely form the foundation — and the roofs, walls and infrastructure––of society's first off-Earth settlements.
The reason we'd use regolith is simple: Escaping Earth’s gravity is expensive. The heavier the payload, the more rocket fuel is needed to propel a spacecraft past the planet’s gravitational pull — and the higher the mission’s price tag. Until there’s an economical alternative to the toxic and costly rocket propellants used today, fuel costs will inhibit the launch of astronauts who insist on carrying everything they’ll ever need in the capsule alongside them.
Instead, they’ll have to be resourceful. Rather than transporting hand tools and habitats, crews will be expected to make them along the way. As many space exploration experts predict, in situ resource utilization, the practice of “living off the land” and harnessing local resources for long-term exploration, has become fundamental to humanity’s future in space. And few resources will be as accessible as regolith.
“Regolith is almost ubiquitous on planets,” says Phillip Metzger, a planetary scientist with the Florida Space Institute at the University of Central Florida. According to Metzger, who spent more than 30 years as a physicist and engineer focused on space exploration at NASA, regolith is abundant on asteroids and moons as well, formed from meteoroid impacts over billions of years. “Wherever there are planets, there is always leftover material from small bodies that bombard those planets and break up the surface material to create regolith.”
Far from some alien substance, regolith also exists all over Earth, though it goes by more familiar names — dirt, dust, soil, sand. Elsewhere, however, “regolith is basically just moon dirt or Mars dirt,” says Jennifer Edmundson, a geologist and in-space manufacturing engineer at Jacobs Space Exploration Group, a NASA contractor. Just as humans have used dirt to build shelters on Earth for tens of thousands of years, experts say space colonists will have to turn to regolith to avoid the dangers of extraterrestrial exposure, from fatal levels of solar radiation to cosmic thermal swings and micrometeoroids.