One giant breath for mankind

From 1969 to 1972, Nasa probed the Moon as many as six times in the hope of finding signs of life. As a result, scientific data gathered from manned lunar expeditions revealed that the Earth’s Moon is lifeless and incredibly barren.

During these endeavours, however, scientists learned of a fine dust with peculiar properties on its surface: lunar dust, which smells like gunpowder but stings like shards of glass. Amazingly, it’s this same pesky dust that holds a promise of life. In fact, for the first time, traces of oxygen have been found on the Moon, more so in its dust.

An analysis of lunar regolith, a top layer of loose soil and broken rock harvested by Nasa’s Apollo-era astronauts, confirms that the Moon’s crust contains 40 to 50 per cent oxygen by mass, but in the form of oxide. And with this knowledge, researchers at ESA have now deduced a chemical process to extract pure, usable oxygen from the regolith. Taking it a step further, a prototype oxygen plant has been set up in the Materials and Electrical Components Laboratory of the European Space Research and Technology Centre, the Netherlands, to achieve these results.

“Having our own facility allows us to focus on oxygen production, measuring it with a mass spectrometer as it is extracted from the regolith simulant,” says Beth Lomax, a PhD student at the University of Glasgow. “Being able to acquire oxygen from resources found on the Moon would obviously be hugely useful for future lunar settlers, both for breathing and in the local production of rocket fuel.”

Found in remnants of lava flows, the lunar regolith simulants are made from crushed volcanic rocks, which have similar chemical properties and particle size distribution to lunar soil, explains ESA research fellow Alexandre Meurisse.

This simulant is sold commercially and, while there are suppliers across the globe, ESA outsourced the dust from a non-profit lab owned by the University of Central Florida.

All in all, it’s safe to say that lunar dust simulant is plentiful on Earth. The real challenge, however, lies in extracting oxygen out of the simulant. To achieve the desired result, researchers at ESA made use of a method called ‘molten salt electrolysis’, a brainchild of UK-based company Metalysis that specialises in commercial metal and alloy production.

Here’s how it works: a simulant of Moon dust, more formally known as lunar regolith, is placed in a metal container followed by molten calcium chloride salt, which serves as an electrolyte. The mix is then heated to 950°C. At this temperature, the regolith is still a solid. However, when an electric current flows through the mixture the oxygen splits from the mix, leaving behind a heap of usable metal alloys.

“This is another useful line of research, to see what are the most useful alloys that could be produced from them, and what kind of applications could they be put to,” says Meurisse. “Could they [metal alloys] be 3D-printed directly, for example, or would they require refining? The precise combination of metals will depend on from where on the Moon the regolith is acquired – there would be significant regional differences.”

The experimental plant takes about 50 hours to extract 96 per cent of the total oxygen from the regolith. Even better, as much as 75 per cent of the oxygen can be extracted in the first 15 hours. This is a promising result, one that can revolutionise space exploration.

For now, the oxygen obtained as a result of molten salt electrolysis is aired out through an exhaust pipe. Future enhancements to the pilot plant will presumably ensure steady operation, with storage of oxygen ticked off the list. Cryogenics, for instance, allows oxygen to be stored in liquid form.

Since the extraction process is insensitive to minor mineral variations, similar accuracy (96 per cent oxygen) is expected in the case of real lunar dust. Meurisse adds there is already a lot of knowledge in Europe for purifying and storing oxygen as it is already used as rocket fuel and for many other terrestrial applications.

Space-habitat building has a lot to do with finding apt resources for construction. As it turns out, scientists at ESA have already solved this enigma. Using nothing more than simulated lunar soil and concentrated sunlight, ESA scientists were able to develop sturdy, 3D-printed bricks. As futuristic as it sounds, the Moon dust bricks can be easily used for building roads, launch pads and habitats for Moon settlers.

Adding to the appeal of Moon dust is ESA’s recent invention; breathable oxygen and usable alloys made merely out of lunar dust simulant. With innovations like these, a sustainable colony on the Moon seems all the more plausible and not far-fetched.

In fact, Meurisse expresses his personal thoughts on the concept of a ‘Moon village’, describing it as a vision of the future. “Every step we take towards sustainability on the Moon makes this vision more plausible,” he explains. “Being able to produce oxygen at the surface is one of these steps.”