Moon mud might contaminate lunar researchers’ water provide

Water treatment is big business on Earth, with companies offering everything from desalination to creating the right pH for drinking water. But there won't be a comparable engineering infrastructure on the Moon to support the astronauts trying to establish a permanent base there. And there's one particular material that makes water treatment even more difficult – lunar dust.

We've written many times about the health problems caused by lunar regolith, so it stands to reason that you wouldn't want to drink it. In addition, the grinding dust can cause problems with seals such as those used in electrolyzers to produce rocket fuel from on-site water supplies. It can even affect the water treatment plant itself.

Unfortunately, this contamination is unavoidable. Moon dust is far too sticky and electrostatically charged to be kept completely separate from the machines that would recycle or clean the water. So a group of researchers from DLR in Germany decided to test what would happen if lunar regolith was intentionally dissolved.

Fraser interviews Dr. Kevin Cannon, an expert in lunar dust containment.

The short answer, not surprisingly, is nothing good. Dissolved lunar regolith causes pH, turbidity and aluminum concentrations to exceed the World Health Organization's limits for safe drinking water. This occurred even with short exposure times (2 minutes) and static pH levels, since a 5.5 pH buffer was used in some of the experiments.

For these experiments, they did not use real lunar dust, but rather a simulant modeled on the regolith brought back during the Apollo 16 mission. It mimics the regolith that is thought to be most similar to the Artemis landing sites. In addition to the pH changes and the exposure time (up to 72 hours), the authors also varied the amount of dissolved oxygen in the system and the particle size of the simulant.

These negative results occurred in every test variation, regardless of which combination of the four control variables was used. Ultimately, this means that engineers must develop a system to filter the water from these deposits before it can be returned to the overall water system.

After taking the first photo of the boot print, astronaut Buzz Aldrin approached the small rock and took this second shot. His boot was already completely covered in sticky dust.
Photo credit: NASA

The paper examined several possible solutions for this water treatment system. Each of the exceeded limits requires its own treatment method. According to the author, the first requirement is to reduce turbidity. To do this, they suggest performing standard filtration or allowing the dust particles to settle.

Next, aluminum removal is important. Another experiment showed that plants growing in lunar soil showed signs of aluminum toxicity. Other ions, including calcium, iron, and manganese, also need to be removed, as they were above acceptable levels in some but not all test batches. Removing these ions would require a reverse osmosis process, or ion exchange. Ion removal is also critical for a fully functional electrolyzer system.

The authors ultimately seemed to be developing a platform for testing and validating water purification processes for future lunar exploration missions. Given the results of their experiments, there will undoubtedly be further rounds of testing and plenty of technological development to work on solving these engineering challenges. After all, astronauts on the Moon will need to drink water – and it won't just come from bottles from Earth.

Learn more:
Freer, Pesch & Zabel – Experimental study to characterize water contaminated by lunar dust
UT – The moon is poisonous
UT – Astronauts will carry dust into the Lunar Gateway. Is that a problem?
UT – Moon dust is still one of the biggest challenges in lunar exploration

Cover image:
Turbidity samples of a portion of the dissolved regolith.
Credit – Freer, Pesch and Zabel

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