Inside a giant sphere, the engineers pored over their equipment. Before them stood a silvery metal contraption swathed in colourful wires – a box that they hope will one day make oxygen on the moon.

Once the team vacated the sphere, the experiment began. The box-like machine was now ingesting small quantities of a dusty regolith – a mixture of dust and sharp grit with a chemical composition mimicking real lunar soil.

Soon, that regolith was gloop. A layer of it heated to temperatures above 1,650C. And, with the addition of some reactants, oxygen-containing molecules began to bubble out.

“We’ve tested everything we can on Earth now,” says Brant White, a program manager at Sierra Space, a private company. “The next step is going to the moon.”

Sierra Space’s experiment unfolded at Nasa’s Johnson Space Center this summer. It is far from the only such technology that researchers are working on, as they develop systems that could supply astronauts living on a future lunar base.

Those astronauts will need oxygen to breathe but also to make rocket fuel for spacecraft that might launch from the moon and head to destinations further afield – including Mars.

Lunar base inhabitants might also require metal and they could even harvest this from the dusty grey debris that litters the lunar surface.

Much depends on whether we can build reactors able to extract such resources effectively or not.

“It could save billions of dollars from mission costs,” says Mr White as he explains that the alternative – bringing lots of oxygen and spare metal to the moon from Earth – would be arduous and expensive.

Luckily, the lunar regolith is........

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