When NASA sets up its permanent base on the moon, how will the colonists keep themselves going? How will they get oxygen to breathe, and where will they find building materials, not to mention silicon for all the solar panels they will need?
Easy, says Geoffrey Landis of NASA’s Glenn Research Center in Cleveland, Ohio. All these materials can be made from moon dust.
“Oxygen, building materials and silicon can all be made from moon dust”
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Landis’s plan is to use just one chemical shipped from Earth – potassium fluoride, in crystal form – to extract a range of useful materials from the “regolith” that makes up the moon’s surface.
In 2005 NASA launched the Moon Regolith Oxygen challenge to spark research into extracting oxygen from this lunar soil (91av, 28 May 2005, p 6). Landis sees the fine, grey powder as having much more potential than that, however.
Regolith locks up silicon, iron, aluminium and at least seven other metals as oxides. To liberate them, Landis plans to use two forms of solar power. First, solar panels will generate electricity to break up potassium fluoride via electrolysis, releasing fluorine gas. Then the gas will be pumped over regolith that has been heated to more than 600 °C by a mirrored solar energy concentrator, a device that has been successfully tested on the International Space Station.
The gas converts iron, silicon and aluminium oxides into fluoride salts, which can then be electrolysed to recover the silicon and metals. The reactions also liberate oxygen, which could be used for life support, and releases the fluorine in the salts as gas once more.
As potassium fluoride is not found on the moon, Landis’s scheme does not give moon dwellers complete self-sufficiency. If the fluorine gas produced could be fed back into the regolith reaction chamber, at least the shipment from Earth would only need to be a one-off. This might prove difficult, according to materials scientist Alex Freundlich of the University of Houston, Texas. If it can be made to work, though, it would also prevent lunar pollution by waste fluorine: “The environmental impact would be pretty small,” says Landis.
