ESA launches the first prototype oxygen extraction plant from the lunar regolith

📷 | ESA

NASA's Artemis mission will mark the return of humans to the moon since the last Apollo mission in 1972. But bringing astronauts to lunar soil is not the ultimate goal of space agencies. Some plans aim to install real permanent lunar bases in order to carry out scientific experiments and test different engineering techniques. One of the essential resources to manage to maintain these inhabited bases is oxygen. Even if the Moon does not have an atmosphere, the regolith that lines its surface contains a lot of oxygen. And to test the technique of extracting oxygen from the regolith, ESA will host the first large-scale prototype factory using this process.


Last year, researchers published an article on how to extract oxygen from a lunar dust simulator (regolith); now the first prototype oxygen plant will attempt this extraction on a larger scale. If it works, the technology could provide humans with important resources that will aid future lunar missions, and perhaps even allow long-term bases and colonies on the Moon.



“ Having our own facility allows us to focus on producing oxygen, measuring it with a mass spectrometer when it is extracted from the regolith simulator. Being able to acquire oxygen from the resources found on the Moon would obviously be extremely useful for future lunar colonists, both for breathing and for the local production of rocket fuel "explains the chemist Beth Lomax of the University of Glasgow , in Scotland.

Oxygen is the main resource necessary for the establishment of permanent manned lunar bases. Geochemists have developed a way to extract the oxygen contained in the regolith. Credits: ESA

Extract the oxygen from the regolith by electrolysis into molten salt

The installation, located at the European Space Research and Technology Center of the European Space Agency in the Netherlands, will use the technique developed by Lomax and his colleagues. Geochemists know, on the basis of samples of the lunar regolith, that oxygen is really very abundant in this material. Between 40 and 45% of the regolith by weight is oxygen.

Using an exact copy of the lunar regolith made on Earth, called a simulator of the lunar regolith, attempts have been made in the past to figure out how to extract oxygen, with poor results - too complicated, too weak, or destructive of the regolith. The Lomax team has remedied this by using a technique called “molten salt electrolysis”.

The electrolysis in molten salt of the regolith extracts oxygen while producing usable metal residues. Credits: Lomax et al., Planetary and Space Science, 2019

First, the regolith is placed in a mesh basket. Calcium chloride - the electrolyte - is added and the mixture is heated to about 950 degrees Celsius, a temperature that does not melt the material. Then an electric current is applied. This extracts oxygen and migrates the salt to an anode, where it can be easily removed. This technique extracts up to 96% of the oxygen from the regolith; as a bonus, the remaining material from this process is a mixture of metal alloys.

Use materials left over from electrolysis

" This is another useful avenue of research, to see what are the most useful alloys that could be produced from these, and for what type of applications could they be used." Could they be 3D printed directly, for example, or would they require refinement? The precise combination of metals will depend on where, on the Moon, the regolith is mined - there would be significant regional differences, "said Alexandre Meurisse of the European Space Agency.



The current configuration of the system is based on commercial deoxidation plants, where oxygen is only a useless by-product which is discharged. However, as the facility evolves, a means of storing oxygen will be included. The end goal, of course, is to develop a system that could work on the Moon, using a real lunar regolith, not a simulator.

Bibliography: ESA opens oxygen plant – making air out of moondust 17/01/2020 http://www.esa.int/Enabling_Support/Space_Engineering_Technology/ESA_opens_oxygen_plant_making_air_out_of_moondust