Skip to main content

Featured

In December, an asteroid the size of the Eiffel Tower will approach Earth. Should you be concerned?

The top layer of the Moon alone contains enough oxygen to sustain 8 billion people for 100,000 years.

The top layer of the Moon alone contains enough oxygen to sustain 8 billion people for 100,000 years.


Along with advancements in space exploration, much time and money has recently been invested in technologies that could allow for effective space resource utilisation. At the forefront of these efforts has been a laser-like focus on determining the best way to produce oxygen on the Moon.

The Australian Space Agency and NASA signed an agreement in October to send an Australian-made rover to the Moon as part of the Artemis programme, with the goal of collecting lunar rocks that could eventually provide breathable oxygen on the Moon.

Although the Moon has an atmosphere, it is very thin and mostly made up of hydrogen, neon, and argon. It's not the kind of gaseous mixture that can support oxygen-dependent mammals like humans.

Having said that, there is plenty of oxygen on the Moon. It's just not in a gaseous state. Instead, it's encased in regolith, a layer of rock and fine dust that covers the Moon's surface. Is it possible to extract enough oxygen from regolith to sustain human life on the Moon?

The range of oxygen

Many minerals found in the ground around us contain oxygen. And the Moon is mostly composed of the same rocks found on Earth (although with a slightly greater amount of material that came from meteors).

The Moon's surface is dominated by minerals such as silica, aluminium, iron, and magnesium oxides. All of these minerals contain oxygen, but not in the form that our lungs can use.

These minerals can be found on the Moon in a variety of forms, including hard rock, dust, gravel, and stones that cover the surface. This material is the result of countless millennia of meteorite impacts on the lunar surface.

Some people refer to the Moon's surface layer as "soil," but as a soil scientist, I'm hesitant to use that term. Soil, as we know it, is a magical substance that only exists on Earth. Over millions of years, a diverse range of organisms worked on the soil's parent material — regolith, which is derived from hard rock — to create it.

The end result is a mineral matrix that was not present in the original rocks. The soil on Earth has remarkable physical, chemical, and biological properties. Meanwhile, the materials on the Moon's surface are essentially regolith in its natural, unaltered state.

One substance goes in, and two come out.

The regolith on the Moon is approximately 45 percent oxygen. However, that oxygen is tightly bound into the aforementioned minerals. We must expend energy in order to break those strong bonds.

If you've ever heard of electrolysis, you've probably heard of this. This process is widely used in manufacturing on Earth, such as the production of aluminium. An electrical current is passed through electrodes into a liquid form of aluminium oxide (commonly known as alumina). To separate the aluminium from the oxygen, an electrical current is passed through a liquid form of aluminium oxide (commonly known as alumina) via electrodes.

The oxygen is produced as a byproduct in this case. The main product on the Moon would be oxygen, with the aluminium (or other metal) extracted as a potentially useful byproduct.

It's a simple process, but there's a catch: it consumes a lot of energy. It would need to be supported by solar energy or other energy sources available on the Moon in order to be sustainable.

Extraction of oxygen from regolith would also necessitate large amounts of industrial equipment. We'd need to convert solid metal oxide into liquid form first, either by applying heat or by combining heat with solvents or electrolytes. We have the technology to do this on Earth, but transporting this apparatus to the Moon – and generating enough energy to power it – will be a formidable task.

Earlier this year, Belgium-based startup Space Applications Services announced the construction of three experimental reactors to improve the electrolysis process of producing oxygen. They plan to launch 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 be provided by the Moon?

Having said that, how much oxygen might the Moon actually provide if we manage to pull it off? As it turns out, quite a bit.

We can make some estimates if we ignore the oxygen trapped in the Moon's deeper hard rock material and only consider regolith, which is easily accessible on the surface.

On average, each cubic metre of lunar regolith contains 1.4 tonnes of minerals, including approximately 630 kilogrammes of oxygen. According to NASA, humans require approximately 800 grammes of oxygen per day to survive. So 630kg of oxygen would be enough to keep a person alive for about two years (or just over).

Let us now assume that the average depth of regolith on the Moon is about ten metres and that we can extract all of the oxygen from it. That is, the top ten metres of the Moon's surface would provide enough oxygen to sustain all eight billion people on Earth for approximately 100,000 years.

This would also be dependent on how well we were able to extract and use the oxygen. Regardless, this figure is incredible!

Having said that, we do have it pretty good here on Earth. And we must do everything in our power to protect the blue planet, particularly its soil, which sustains all terrestrial life without our intervention.

Comments