A team of European Space Agency (ESA) scientists think it has found a way to produce oxygen from lunar regolith, and it has opened a “prototype oxygen plant” inside a Dutch lab to refine the process.
“Being able to acquire oxygen from resources found on the Moon would obviously be hugely useful for future lunar settlers, both for breathing and in the local production of rocket fuel,” said Beth Lomax of the University of Glasgow in a statement.
Samples of moon dust returned from the lunar surface confirm that the material is made up of 40-45% oxygen by weight. The oxygen is bound up chemically in the form of minerals and glass oxides.
The European Space Research and Technology Centre (ESTEC), based in Noordwijk, Netherlands, uses a method called “molten salt electrolysis,” in which a simulated regolith is heated to 940 degrees Centigrade in a metal basket and molten calcium chloride salt acts as an electrolyte. Passing a current through the material extracts the oxygen and causes it to migrate to an anode where it can be collected.
As a byproduct, the process creates useful metal alloys. “The production process leaves behind a tangle of different metals,” says Alexandre Meurisse, ESA research fellow, “and this is another useful line of research, to see what are the most useful alloys that could be produced from them, and what kind of applications could they be put to.”
The precise combination of metals will vary depending on where on the Moon the regolith is coming from. There would be significant regional differences.
Says Tommaso Ghidini, head of ESA’s Structures, Mechanisms and Materials Division: “We’re shifting our engineering approach to a systematic use of lunar resources in-situ. We are working with our colleagues in the Human and Robotics Exploration Directorate, European industry and academia to provide top class scientific approaches and key enabling technologies like this one, towards a sustained human presence on the Moon and maybe one day Mars.”
Commentary: Oxygen is a crucial element in both breathable air and water. The invention of what appears to be an economical process for extracting oxygen from regolith eliminates a major barrier to the large-scale settlement of the Moon. However, this process is not by itself sufficient to create breathable air. On Earth, oxygen comprises roughly 20% of the atmosphere. It would be poisonous at 100%. To make air breathable, it needs to be mixed with nitrogen (or some other inert gas). It is not clear from this article where that nitrogen might come from. Likewise, the combination of oxygen with hydrogen could create limitless supplies of rocket fuel. But it’s not clear where the hydrogen will come from. One additional question: How much calcium chloride is required for the process, and where will that come from?
Despite these caveats, the ability to mine and extract oxygen on a large scale represents a tremendous step in lunar settlement.