Establishing a permanent lunar base is a priority for several space missions, including NASA’s Artemis program. But, in order for this project to succeed, it needs water.
Water pollution is one of the most serious health concerns here on Earth — and it would be no different for space explorers. Whether you’re on the International Space Station, in a shuttle, or on the moon, you need clean, safe, drinking water. For moon exploration, which has become a priority for NASA, this could be very tricky.
Moon explorers would have to rely on a supply of ice which, thankfully, exists on the moon. They will need a purification system that cleanses the ice and makes it safe for drink — but even then, the problem isn’t over. Lunar dust, known as regolith, will be very hard to keep out of the system.
Lunar dust covers the entire surface of the Moon, with about 20% of the bulk regolith composed of particles smaller than 20 micrometers. This dust can contaminate water systems in multiple ways, including through the cleaning of dust-contaminated spacesuits and the operation of water extraction hardware on the lunar surface. The fine particles can clog instruments and pipes, reduce the effectiveness of seals, and adversely affect water recovery systems.
Moon dust and water
We have a pretty good idea of what regolith is and looks like from the Apollo missions, which brought back several samples. It’s abrasive and electrostatically charged, so it will “stick” to machinery and seals. A group of researchers from the German Aerospace Center (DLR) wanted to see what would happen if regolith got into the drinking supply.
They didn’t use regolith directly (because there’s so little of it to go around) but rather a substitute modeled after samples brought back from the Apollo missions. This is thought to be very similar to the type of dust found in the areas where the Artemis missions will land. They dissolved various amounts of this substance into water and tested various exposure times, ranging from a few minutes to 72 hours. They also tested several particle sizes and different levels of dissolved oxygen.
For all the simulated scenarios, the regolith made the water unsafe to drink. The pH, turbidity, and aluminum concentrations all exceeded World Health Organization benchmarks for safe drinking water. In other words, if lunar dust goes into the drinking supply, then it’s not really safe to drink. This goes to show that the lunar water filtration systems will need to be absolutely foolproof and eliminate all the dust around.
The authors suggest that lowering the turbidity would be the first requirement. This would be relatively simple to solve as it could be done through simple, mechanical filtration (or simply allowing the particles to settle). Then, the most important part would be to remove the aluminum. This would be more difficult.
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It’s not the first time aluminum has come up as a contaminant for moon missions: plants grown on lunar soil also show signs of toxicity. To remove it from water, the most straightforward method would likely involve a reverse osmosis process or ion exchange. Additional ions, like calcium or iron, also showed up in some samples (but not all) above the safe levels.
The bottom line is that we have ways to clean these contaminants from water, but we need to account for this for any long-term moon mission.
The researchers are now working on different scenarios as well as potential solutions for regolith contamination. As space agencies move closer to establishing a permanent presence on the Moon, understanding and mitigating lunar dust contamination will be vital for ensuring the health and safety of astronauts and the success of lunar missions.
Ultimately, astronauts on the moon will need to drink water, and they can’t bring it all from home. Without a reliable system to filter water, the Artemis project (and any lunar base program) cannot succeed.
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