Take a deep breath anywhere on the surface of planet Earth. No matter how high, how low or how polluted it is, you’ll still get enough oxygen to sustain you for a while. Plant your face in a pile of dirt and take a deep breath (metaphorically please) and you get lungs filled with dirt. Take a deep breath anywhere on the surface of the Moon and you’re about to die from lack of oxygen. Plant your face in a pile of Moon dirt and, with the right equipment, you and your descendants will be breathing for 100,000 years. Don’t believe it? Meet Dr. John Grant, lecturer in Soil Science at Australia’s Southern Cross University.
“Although the Moon does have an atmosphere, it’s very thin and composed mostly of hydrogen, neon and argon. It’s not the sort of gaseous mixture that could sustain oxygen-dependent mammals such as humans. That said, there is actually plenty of oxygen on the Moon. It just isn’t in a gaseous form. Instead it’s trapped inside regolith — the layer of rock and fine dust that covers the Moon’s surface. If we could extract oxygen from regolith, would it be enough to support human life on the Moon?”
In an article published in The Conversation, Dr. Grant explains where the Moon’s oxygen is hiding – in the blanket of soil, dust and broken rocks above the next layer, which is solid bedrock. Regolith, whose Greek roots means ‘blanket rock’, has been in the space news lately as China’s lunar rover and NASA’s Perseverance Mars rover have been taking samples from their respective regoliths. According to Grant, this is a good – potentially lifesaving – idea on the Moon because its regolith is made up of approximately 45% oxygen. That’s where the headline-grabbing calculation of “there’s enough oxygen on the Moon for 8 billion people 100,000 years comes from.
However, there’s a “but” -- that oxygen is tightly bound into oxygen-bearing silica, aluminum, iron oxide and magnesium oxide and energy is needed to free it. Fortunately, Grant knows how, which is why in October 2021 the Australian Space Agency and NASA signed a deal to send an Australian-made rover to the Moon under the Artemis program to collect lunar rocks filled with what might someday release their breathable oxygen.
“Extracting oxygen from regolith would also require substantial industrial equipment. We’d need to first convert solid metal oxide into liquid form, either by applying heat, or heat combined with solvents or electrolytes. We have the technology to do this on Earth, but moving this apparatus to the Moon – and generating enough energy to run it – will be a mighty challenge.”
Grant assumes the equipment will be solar-powered, although some other Moon-derived energy might be feasible. It would require digging a cubic meter of lunar regolith and breaking down the 1.4 tons of minerals which the cube would contain on average. That operation would release about 630 kg of oxygen. NASA’s plans call for providing 800 grams of oxygen a day to the next lunar astronauts, so 630 kg oxygen would last one person a little over two years. Extrapolating further, removing the regolith down an average of ten meters and extracting all of the oxygen would give 8 billion people 100,000 years of oxygen.
What are we waiting for? Well, besides the surmountable technical challenges, there’s the ethical dilemma – removing the top ten meters of regolith on the Moon will make it look like the scarred areas of the Earth that have been strip-mined for their oxygen-killing coal and other minerals. Making that decision would undoubtedly depend on why 8 billion humans were trying to escape Earth for some fresh air.
Are we ready to breath dirt? Or are we breathing it already?