In a groundbreaking experiment, engineers at Sierra Space, a private aerospace company, are one step closer to turning the moon into a self-sustaining base for future astronauts. Inside a massive spherical chamber at NASA’s Johnson Space Center, the team tested a machine designed to extract oxygen from lunar soil—specifically, regolith, a mixture of dust and grit that mirrors the moon’s surface.
The machine, a silvery box surrounded by colorful wires, ingests regolith and heats it to temperatures above 1,650°C. With the addition of chemical reactants, oxygen molecules begin to bubble out, simulating the extraction process that would take place on the lunar surface.
As Sierra Space program manager Brant White puts it, "We’ve tested everything we can on Earth now. The next step is going to the moon." This test is part of NASA’s broader initiative to develop technologies that will support astronauts living on a future lunar base, particularly in extracting vital resources like oxygen and metal, both of which will be needed for survival and space exploration.
Astronauts on the moon will need a reliable source of oxygen not only for breathing but also for fueling rockets. Oxygen extracted from the lunar regolith could serve as the oxidizer for rocket fuel, enabling missions to farther destinations, such as Mars. Currently, transporting oxygen from Earth to the moon would be costly and inefficient, making in-situ resource utilization (ISRU) a key part of long-term lunar colonization.
The challenge lies in the harsh lunar environment. Sierra Space’s technology, known as the carbothermal process, extracts oxygen by heating the regolith. However, this process is complicated by the regolith’s abrasive texture, which wears down the machinery over time. "It gets everywhere, wears out all sorts of mechanisms," says White.
The most significant obstacle, though, is lunar gravity—only one-sixth that of Earth’s—which cannot be replicated in experiments on Earth or even in orbit. It’s only once the system is tested on the moon in real low-gravity conditions that its true potential can be measured. Sierra Space estimates that a test on the moon could occur as soon as 2028.
The moon’s weak gravity may hinder certain oxygen-extraction processes, especially those that rely on the formation of oxygen bubbles. Paul Burke, a researcher at Johns Hopkins University, and his colleagues published a study on molten regolith electrolysis, a process in which electricity is used to split lunar minerals to extract oxygen. The process involves forming oxygen bubbles within molten regolith, but the low gravity could slow their rise, making it harder for the bubbles to detach from electrodes.
In response, Burke’s team is exploring solutions such as vibrating the system to help dislodge the bubbles or using extra-smooth electrodes. Meanwhile, Sierra Space’s carbothermal process avoids the bubble issue, as oxygen forms freely within the regolith, reducing the likelihood of bubbles getting stuck.
The extraction of oxygen is only the beginning. Lunar regolith is also rich in valuable metals such as iron, titanium, and lithium, which could be harvested for use in building infrastructure on the moon. Palak Patel, a PhD student at MIT, is working on a system to extract both oxygen and metals from the regolith through molten regolith electrolysis.
Patel and her team are also addressing the gravity issue by using sound waves to dislodge the oxygen bubbles. "We’re really looking at it from the standpoint of, ‘Let’s try to minimize the number of resupply missions,’" Patel says. This approach aims to reduce reliance on Earth for supplies, making a lunar base more sustainable.
Patel's team is also investigating ways to melt regolith into a strong, glass-like material that could be used to create construction materials, such as hollow bricks. These bricks could be used for building structures on the moon, including protective walls against radiation.
As engineers and researchers continue to test and refine these technologies, the possibilities for a self-sustaining lunar base grow ever closer. The ability to extract oxygen, metal, and other resources from lunar regolith could not only support human life on the moon but also lay the groundwork for future missions to Mars and beyond. With further innovation and testing, the moon may one day become a thriving hub for space exploration, free from Earth’s dependency.
"We’re looking at a future where astronauts can live and work on the moon, relying on the resources around them," White says. As these technologies continue to develop, the dream of a permanent human presence on the moon seems increasingly within reach.