- 45% oxygen is trapped in minerals such as silica, aluminum, iron, and magnesium.
- NASA estimates that humans require about 800 grams of oxygen per day to survive.
- NASA and the Australian Space Agency launch a Lunar rover under the Artemis program.
Recently, we’ve seen a great deal of effort and money put into technologies that could allow the effective utilization of space resources along with advancements in space exploration. An important focus of all these endeavors has been developing the most efficient way to produce oxygen on the Moon. NASA and the Australian Space Agency signed a deal in October 2021 to launch a Lunar rover made in Australia under the Artemis program. Moon rocks collected by the mission may eventually provide breathing oxygen to the Moon.
There is an atmosphere on the Moon, but it is very thin and mostly made up of hydrogen, neon, and argon.
There’s no way humans or other oxygen-dependent mammals can live in this type of gaseous mixture. On the other hand, the Moon has plenty of oxygen. There just isn’t any gaseous oxygen present. Instead, it’s trapped inside regolith, the fine dust and rocks layer covering the lunar surface. Would we be able to support human life on the Moon if we could extract oxygen from regolith?
The breadth of oxygen
In the ground around us are many minerals which contain oxygen. Moon rocks are mostly made from the same materials as rocks on Earth (although there is a little more material that came from meteors). Several minerals dominate the lunar landscape, including silica, aluminum, iron, and magnesium oxides. Oxygen is present in all of these minerals but not in a form accessible to our lungs.
There are a few different minerals on the Moon, including hard rock, dust, gravel, and stones covering the surface. Over countless millennia, meteorites have crashed into the lunar surface, leaving this material behind. It is common to call the Moon’s surface layer “soil”, but I have reservations about the term as a soil scientist.
Our knowledge of soil is pretty magical since it’s something that only happens on Earth. It was formed over millions of years by a wide range of organisms interacting with the soil’s parent material, regolith, which is derived from hard rock. Consequently, the resulting matrix contains minerals that were unavailable in the original rocks. Earth’s soil is characterized by many unique physical, chemical, and biological properties. As a result, the surface of the Moon is primarily regolith, untouched by any human intervention.
What is this regolith?
On the Moon, regolith is comprised of about 45 percent oxygen, much of which is trapped in minerals such as silica, aluminum, iron, and magnesium. As mentioned in The Conversation, the Moon’s surface has remained unchanged since its formation from its original terrain. While Earth’s soil is formed from the interactions between organisms and the planet’s surface, the Moon’s remains unchanged. Oxygen can only be reached on Moon’s surface if an enormous amount of energy is applied. Bypassing current electrolysis would help the Moon’s atmosphere become oxygen-rich. Byproducts of the electrolysis would be aluminum.
One substance goes in, two come out.
In the regolith of the Moon, oxygen makes up 45 percent of the composition. However, the oxygen is presently tightly bound up in the minerals mentioned above. Putting energy into breaking up those strong bonds will help. If you’ve ever used electrolysis, you probably know what I’m talking about. In manufacturing, such as manufacturing aluminum, this process is commonly used on Earth. A liquid form of aluminum oxide (widely called alumina) passes an electrical current to separate the aluminum from the oxygen through electrodes.
A byproduct is an oxygen, in this case. The main product of the Moon’s mining operations would be oxygen, with aluminum (or another metal) being a potential byproduct. Processes like this are relatively straightforward, but there’s one catch: it takes a lot of energy. This process would need to be powered by solar energy or other fuel sources available on the Moon to be sustainable. In addition to industrial equipment, deep drilling would be required to extract oxygen from the regolith. To do this, we would need to first turn solid metal oxide into liquid.
This could be accomplished by applying heat or by heating in combination with solvents and electrolytes. While we have the technology to achieve this on Earth, transportation of the apparatus to the Moon and generating enough power to run it is an enormous challenge. Space Applications Services, a startup in Belgium, announced earlier this year that it would build three experimental reactors to develop a process for producing oxygen via electrolysis. A European Space Agency mission called ISRU (in-situ resource utilization) is expected to send the technology to the Moon by 2025.
How much oxygen could the Moon provide?
However, how much oxygen might the Moon actually provide when we do manage to do it? The answer is quite a lot, in fact. We can estimate the amount of oxygen if we ignore the oxygen in the Moon’s deeper hard rock materials and focus only on the regolith, which is readily accessible on the surface. Approximately 630 kilograms of oxygen are contained in each cubic meter (35 square feet) of lunar regolith.
NASA estimates that humans require about 800 grams of oxygen per day to survive. A person would be able to survive for almost two years on 630 metric tons of oxygen. Consider the case where we can extract all oxygen from regolith on the Moon, with an average depth of about ten meters. It would take approximately 100,000 years for the top ten meters of the Moon’s surface to supply enough oxygen for all eight billion people on Earth.
Depending on how efficiently we managed to extract and use oxygen, the result would differ. This conclusion is still quite impressive, however! Nevertheless, we live in relatively good circumstances on Earth. We have a responsibility to protect the blue planet and its soil, which is the only way for all terrestrial life to continue to exist without an effort on our part.