We’ve lately seen a lot of effort and money poured in technology that might allow successful space resource use, alongside advancements in space exploration. Finding the most efficient means to manufacture oxygen on the Moon has been at the forefront of these efforts.
As part of the Artemis program, the Australian Space Agency and NASA agreed to deploy an Australian-built rover to the Moon in October. The mission’s objective is to gather lunar rocks that may one day be used to create breathable oxygen on the Moon.
The atmosphere of the Moon is there, although it is relatively thin and mostly made of hydrogen, neon, and argon. It is not the kind of gaseous combination that might support creatures that depend on oxygen, like humans.
Having said that, the Moon has an abundance of oxygen. Simply said, it’s not a gas. Regolith, the layer of rock and fine dust that covers the Moon’s surface, is where it is actually trapped. Would the oxygen we could extract from regolith be sufficient to sustain life for humans on the Moon?
The breadth of oxygen
Numerous minerals in the earth near us contain oxygen. Additionally, most of the rocks that make up the Moon are also found on Earth (although with a slightly greater amount of material that came from meteors).
The terrain of the Moon is dominated by minerals including silica, aluminum, iron oxides, and magnesium oxides. While oxygen is present in all of these minerals, it is not in a form that our lungs can access.
These minerals can be found on the Moon in a variety of forms, such as hard rock, dust, gravel, and stones that blanket the surface. This stuff is the consequence of thousands of years’ worth of meteorites colliding with the lunar surface.
I hesitate to use the term “soil” because I study soils, although some people refer to the lunar surface layer as such. The soil we are familiar with is actually rather miraculous and only exists on Earth. It was produced over millions of years by a huge variety of creatures working on regolith, which is generated from hard rock and is the parent material of soil.
One substance goes in, two come out
The regolith on the Moon contains around 45% oxygen. But the minerals described above contain a strong bond with that oxygen. We need to exert energy to dismantle such powerful relationships.
If you are familiar with electrolysis, you might be aware of this. This procedure is widely utilized in industry on Earth, including the production of aluminum. In order to separate aluminum from oxygen, an electrical current is conducted through a liquid form of aluminum oxide (often referred to as alumina) using electrodes.
In this instance, the production of the oxygen is a byproduct. The primary product on the Moon would be oxygen, with the extraction of aluminum (or another metal) serving as a potential byproduct.
It’s a rather simple operation, but there’s a catch: it uses a lot of energy. It would require the support of solar energy or other energy sources found on the Moon in order to be viable.
Large industrial machinery would also be needed to extract oxygen from regolith. The solid metal oxide would first need to be transformed into a liquid state, either by heating it or heating it in combination with solvents or electrolytes. On Earth, we have the capability to achieve this, but getting this equipment to the Moon and finding enough energy to power it will be a significant issue.
Earlier this year, Belgium-based startup Space Applications Services announced it was building three experimental reactors to improve the process of making oxygen via electrolysis. They expect to send the technology to the Moon by 2025 as part of the European Space Agency’s in-situ resource utilisation (ISRU) mission.
How much oxygen could the Moon provide?
However, how much oxygen might the Moon truly provide if we are successful? As it turns out, quite a bit.
We can get some estimations if we disregard the oxygen bound up in the Moon’s subsurface hard rock material and only take into account the regolith, which is easily accessible on the surface.
The average amount of minerals in a cubic meter of lunar regolith is 1.4 tonnes, including around 630 kg of oxygen. According to NASA, to survive, people need to breathe in roughly 800 grams of oxygen every day. Therefore, 630 kg of oxygen would sustain a human for almost two years (or just over).
Let’s now assume that we can fully extract the oxygen from the regolith, which is thought to be on average roughly 10 meters deep on the Moon. The oxygen needed to sustain all eight billion people on Earth for almost 100,000 years would be found in the top ten meters of the Moon’s surface.
Additionally, how successfully we were able to collect and utilize the oxygen would determine this. Whatever the case, this number is rather astounding!
Having said that, life is generally nice for us on Earth. And we ought to do every effort to safeguard the blue planet, particularly its soil, which continues to sustain all terrestrial life without our even trying.