Universe Today has a rather interesting article today, all about how moon dust may be harmful to humans. And it’s an interesting thing to consider. While not every world is as obviously lethal as Venus, any other place where human beings can set foot can and will be chemically very different to our home here on Earth.
Moon dust is dry and caustic. The word regolith, the technical term for it, even sounds dry and caustic. Say it out loud. Regolith. See what I mean? Also, as many people might now know, it smells like gunpowder. Moon dust caused a number of problems for the Apollo astronauts, not least the fact that its fine but sharp particles caused some astronauts some quite serious respiratory problems! While the Universe Today article (and the arXiv paper which it discusses) use the word “toxic”, however, the articles mostly talk about mechanical effects rather than actual toxicity. Quite rightly so, because lots of tiny and extremely sharp dust particles are not good for any part of you. Especially not your lungs. Or your eyes. Being as it was apparently abrasive enough to wear through several layers of kevlar on the Apollo astronauts’ boots, needless to say, it’s not going to be very good for your skin. Chances are that long term exposure to moon dust would also cause long term chronic respiratory conditions like silicosis. So in light of all of this, you’d be forgiven for thinking that ground up moon rocks are pure poison.
But are they actually toxic? Well that’s a more interesting question. This chart shows a comparison of Earth and lunar soils to show the constituent atoms. If you consider this carefully, you can pick out a few things about lunar soil.
For one, just like on Earth, there’s a lot of oxygen in moon dust. This makes sense, because the minerals found there are likely to be oxides just like on Earth. Silicates, for instance, are obviously the main component. Just like most of the dust in the rest of the Universe. In fact, all of the other elements seen here are likely to exist as oxides. These include aluminium oxide (alumina, used as an abrasive in industry), calcium oxide (quicklime, well known for its caustic properties) and magnesium oxide. Not exactly poisonous, but calcium oxide is caustic enough that I’d rather not get any on my skin. Let alone in my lungs.
Interestingly, while not so great for people, moon dust seems to pose less of a problem to plants. An article posted at Boing Boing, for instance, talks about some old NASA studies which showed that plants are essentially unaffected by exposure to lunar soil. It’s not quite the same thing as actually growing plants in moon dust, but at least that moon dust isn’t immediately lethal. Though as another story, this time from io9, details, plants won’t grow directly in lunar soil (or in this case, a close analogue of it). Instead, growing a plant in moon dust needs another kind of Earth life to help out – bacteria. Apparently, add certain types of bacteria into the equation, and that regolith could be broken down into nutrients which plants might be able to make better use of. Fascinating.
So in summary, raw moon dust is really not good for you. Especially as it’s clingy and easy to get into spacecraft accidentally, and it’s made of microscopically small but rather sharp particles (see the image below). But if you can keep unwanted dust out of your lunar colony, that same moon dust may be perfectly good for plants to grow in, provided you first treat it correctly.
Upper – NASA/Buzz Aldrin
Middle – Roger Wilco @ Wikimedia Commons
Lower – microscope image of moon dust via redorbit.com