Astronauts could live on the Moon in giant glass balls made from dust, experts say. NASA is funding the development of large-scale spheres that will rise from microwave Moon furnaces like vast bubbles before hardening to form strong transparent structures.
The concept has been devised by US-based Skyeports which has already shown it is possible to blow glass balls from lunar dust or regolith - fragments of rock, minerals and glass that line the Moon's surface.
Though the first spheres are just a few inches wide the aim is to create habitats big enough for astronauts to live, work and grow food inside. The spheres would be built using self-healing glass to seal dents or cracks from meteorites or 'moonquakes' and have embedded solar panels to generate energy.
Skyeports chief executive Dr Martin Bermudez said he hoped one day there would be entire cities of glass spheres linked by sky-bridges on the Moon and beyond.
"Space has always been kind of fascinating for me, and my background was as an architect so I had the chance to start exploring how we can build structures on the Moon or Mars," he said.
"I started to think of the materials that are already on the Moon and sometimes 60% of the lunar regolith is silicates so I thought glass could be what this structure is built from.
"I was originally told glass is too brittle so I started reaching out to scientists and realised it can be adapted and become something stronger than steel.
"I contacted NASA almost two years ago and they really loved the idea."
Building anything on the Moon would be too costly if materials have to be shipped to the surface in spacecraft. The company would get around the problem by sending a microwave furnace that could be used to build multiple space homes. Moon dust would be fed in with giant pipes of gas blowing the melted glass into a sphere.
Skyeports said the design takes advantage of the structural integrity of a sphere - evenly distributing pressure. The transparent glass would help astronauts' mental health.
Dr Bermudez said: "We're going to have to integrate metals into the melt like titanium, magnesium, calcium to help keep the glass strong."
The project is part of NASA's Innovative Advanced Concepts programme which funds futuristic projects. The team plans to test out the blowing technique in a thermal vacuum chamber in January before eventual trials in the International Space Station.
Tests on the Moon itself could happen within the next few years. Humans could be returning within the next five years under NASA's Artemis programme and the space agency is looking for suitable habitats.
"We're in a race against time because Artemis is moving so fast," Dr Bermudez said. Mental health is going to be important on long-duration missions and it will be important for astronauts to be able to see outside and perhaps even see the Earth.
"If we can create layers of bubbles, one surface can be warm and the other cooler, so we create condensation and we can plant vegetables and plants and get an ecosystem going that produces oxygen.
"We are looking into creating a glass shell that can create electricity to power the entire habitat. I'd love to see whole communities of these, a city of them, housing parks, water systems and homes, all connected through glass bridges.
"You will never replicate Earth, but this is something that gets pretty close, and we could even put them into orbit one day."
Clayton Turner, associate administrator for NASA's Space Technology Mission Directorate, said "Our next steps and giant leaps rely on innovation. From developing small robots that could swim through the oceans of other worlds to growing space habitats from fungi, this programme continues to change the possible."