Countries around the world see the 2020s as the decade we go back to the Moon. And this time it's to stay. But there are many things to consider before humans can take up permanent residency on the Moon. An obvious one is breathable air. It can be brought from Earth and recycled once on the Moon, but the best option would be to produce oxygen right there on our satellite.
To achieve this goal, the European Space Agency (ESA) has opened a new lab in its ESTEC facility in the Netherlands. Using the PhD work of Beth Lomax of the University of Glasgow, the team is looking at how to extract the precious element directly from the ground.
The lunar soil, aka the regolith, is rich in oxygen. By weight, it's between 40 and 45 percent oxygen, making O2 the single most abundant element in the regolith. Oxygen is trapped in oxides forming either minerals or glass, so extracting it is no easy task. The work done in the lab will pave the way for what is done on the actual Moon.
"Having our own facility allows us to focus on oxygen production, measuring it with a mass spectrometer as it is extracted from the regolith simulant," Lomax said in a statement. "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."
The oxygen extraction method uses molten salt electrolysis. You take a metal basket and you place molten calcium chloride at 950°C (1,742°F) inside it. Molten salts conduct electricity so it is possible to place electrodes at each end. Putting the regolith in the crucible doesn’t melt the lunar soil, but creates important reactions. Oxygen is liberated and moves to the anode (the positively charged electrode).
The remaining regolith turns into alloys. And some of them could be very useful to a permanent base on the Moon. Given than the Earth is at least a few days away at top speed, a process that has virtually no waste products is very desirable. We are not quite there yet but the team is ready to take on the challenge.
"And now we have the facility in operation we can look into fine-tuning it, for instance by reducing the operating temperature, eventually designing a version of this system that could one day fly to the Moon to be operated there," said ESA research fellow Alexandre Meurisse.
For the last few years, ESA has discussed its plans for a permanent settlement on the Moon by the mid-2030s. The southern pole of the Moon with its caves and ice deposits is viewed as a particularly interesting location for it.