The poisonous side of the moon

Lunar dust could be as harmful to health as asbestos

Covered by moon dust: Apollo astronaut Eugene Cernan after a moonwalk. © NASA
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Dusty threat: The fine dust of the moon could be dangerous to future lunar astronauts. Because it can penetrate deep into the lungs and cause severe cell and DNA damage, as a study shows. The problem: The tiny, sharp-edged particles stick to spacesuits and equipment and are therefore inevitably dragged into the interior of lunar bases and landing ferries - as the Apollo astronauts had to determine.

Already at the first moon landing the astronauts of the Apollo 11 reported about the fine, sticky moon dust. He sat down in their spacesuits, covering all the equipment and soon the interior of the lander. All twelve astronauts of the lunar missions suffered from symptoms that Apollo 17 astronaut Harrison Schmitt described as "lunar hay fever": sneezing, a stuffy nose, a scratchy throat and watery, itchy eyes.

Sharp-edged and tiny

But what about this "lunar hay fever"? And how harmful is the moon dust? It is known that the particles of the lunar regolith differ distinctly from terrestrial dust. Because on the ground wind and water grind all dust and sand grains over time around. However, because the moon has no atmosphere, the lunar dust grains remain sharp-edged.

In addition: Due to the unfiltered radiation, the particles of the lunar regolith, which are between 0.5 and 10 micrometres small, are electrostatically charged. This not only lets them "stick" to all objects, but the low gravity of the moon keeps them in suspension for a long time. "These particles can therefore be easily inhaled and penetrate deep into the lungs, " explains Kim Prisk of the University of California.

Moon dust particles in close-up - typical is the angular, barely rounded shape. © NASA / JSC

As harmful as asbestos?

The problem: Earth nanoparticles, such as asbestos dust, are known to be able to penetrate deep into the lung cells via the air they breathe. There they damage the cells, cause chronic inflammation and can cause DNA damage, which ultimately leads to lung cancer. display

Could the moon dust have a similar fatal effect on future astronauts and inhabitants of lunar bases? "So far, we do not know how bad this dust really is, " explains Prisk. An ESA research project will now investigate this potential health threat in the near future Mond and deepen previous findings. There is already a first study on this and it does not bode well.

Cell death and DNA damage

For this study, Rachel Caston of Stony Brook University, New York and her colleagues investigated the effects of lunar dust analogues on human lung and brain cells. The pseudo moon dust comes from volcanic ash and solidified lava, which are very similar to the lunar regolith. Freshly ground, the particles of these imitations are as small and sharp-edged as the moon dust.

The tests showed that all moon dust imitations were found to be highly cell-damaging. "The particles caused cell death and DNA damage in lung cells and neuronal cells, " report Caston and her colleagues. At concentrations of 20 milligrams on the 3.8 square centimeters of the cell cultures, only about ten percent of the cells survived regardless of whether they were still dividing or already fully differentiated. But even at lower concentrations, an increased cell death was observed, the researchers. Further investigations also revealed that the simulated moondust, similar to asbestos fibers and other nanoparticles, caused DNA damage in the cells.

Apollo astronaut Harrison Schmitt on the moon. Future astronauts must try to get rid of the moondust dust as soon as possible before returning to the housing module. NASA

"Avoid contact"

But what is this harmful effect based on? "The observed cytotoxicity could be caused by both chemical and physical interactions, " say Caston and her colleagues. Thus, the small size of the dust grains increases their surface, thus facilitating, for example, chemical reactions that give rise to aggressive oxygen radicals. At the same time, however, the particles are small enough to penetrate the cells and damage them directly.

"It seems clear that future moon astronauts should avoid inhaling the lunar dust, " the researchers emphasize. However, that should be hard to avoid. Because as soon as the astronauts move outside of their landing or moon bases, the fine dust will stick to their suits and can then easily be dragged into the interior.

It is therefore all the more important, according to the researchers, to further study the biological effects of moondust on human cells and tissues - preferably with real moondust. Only then could the health risk of the lunar regolith be estimated. (GeoHealth, 2018; doi: 10.1002 / 2017GH000125)

(ESA, 11.07.2018 - NPO)