Try again. Fail again. Fail better.

- Samuel Beckett

Several space agencies and private sector companies are exploring advanced methods for building habitable structures on the Moon using lunar regolith (loose dust and rocks in the Moon’s surface) as the primary material. These techniques aim to reduce dependence on materials brought from Earth, in alignment with the principles of In-Situ Resource Utilization (ISRU). We have explored these approaches in depth, and they’ve directly informed the development and refinement of our own L-DEW technology.

Lunar Geopolymers

Geopolymer technology is also under active investigation as a method for turning lunar regolith into strong, cement-like structures using minimal imported materials. The process involves dissolving aluminosilicate minerals from the regolith in an alkaline solution (like sodium hydroxide or sodium silicate), followed by a polymerization reaction that forms a solid silicoaluminate matrix:

  • NASA studies demonstrated that geopolymer concretes maintain adequate strength under vacuum and low-pressure conditions, suitable for constructing lunar habitats and platforms.

  • Recent experiments have even tested using simulated human urine as a liquid component, with only a minor decrease in compressive strength, showing potential for recycling life-support waste into building materials.

  • However, other studies in 2024 revealed that lunar environmental conditions, such as vacuum and extreme temperature cycles, can reduce material strength over time if not properly managed.

Therefore although lunar geopolymers offer good structural strength, compatibility with 3D printing, and the use of local materials, they still require chemical activators brought from Earth, fluids for processing, and careful engineering to ensure long-term durability under lunar conditions.

MICROWAVE AND LASER SINTERINg

Another approach for lunar construction is to directly melt regolith using microwave radiation or high-powered lasers to create solid structures without the need for external binders. This technology is considered highly promising for in-situ construction on the Moon, as it leverages available resources and reduces dependence on materials transported from Earth:

  • Microwave sintering leverages the metallic particles in lunar soil to heat and fuse it into solid structures;

  • Laser sintering uses focused energy beams to weld regolith into landing pads, roads, and construction elements;

The working principle is simple: a carbon dioxide (CO₂) laser or microwave beam is directed onto a layer of regolith, heating it to 1,100 °C to 1,600 °C depending on composition. The particles partially melt and solidify upon cooling, enabling layer-by-layer construction similar to 3D printing.

This technique has been demonstrated feasible for some key applications, such as landing pads and roads, where solid surfaces help control lunar dust dispersion during launches and landings; structural components, like blocks and panels for future habitats and infrastructure; and complex 3D structures fabricated under simulated vacuum conditions, proving the mechanical feasibility for real lunar environments.

However, although laser and microwave sintering fully utilise lunar resources and are highly compatible with autonomous robotic construction, they require enormous amounts of energy and face challenges like precise thermal control and relatively slow construction rates.

Lunar Concrete Lunarcrete

Another promising technique under study is Lunarcrete, a form of concrete made by mixing lunar regolith with molten sulfur instead of water-based binders:

The process involves heating sulfur to around 115 °C, mixing it with regolith or simulants, and pouring the blend into molds. Upon cooling, the sulfur solidifies, binding the particles into a strong, dense structure.

Research led by Professor T. D. Lin and NASA-funded teams has demonstrated that sulfur-based lunar concrete can achieve compressive strengths exceeding 20 MPa, comparable to traditional concrete, even under vacuum and extreme temperatures.

However, although sulfur concrete eliminates the need for scarce lunar water and allows for remelting and repair, later studies highlighted a key challenge: sulfur can sublimate (slowly dissipate) under prolonged vacuum exposure, potentially weakening structures unless protective coatings are applied. Other challenges are toxic gas emissions during production, and uncertain sulfur availability depending on the lunar site.

3D PRINTING WITH LUNAR REGOLITH AND BINDER

Space agencies like NASA, ESA, and private companies such as ICON are exploring 3D printing systems that mix lunar dust with various binders to create building materials:

Some approaches use magnesium oxide to form Sorel cement-like composites, which have mechanical properties comparable to conventional concrete;

Others explore thermoplastic polymers or organic binders mixed directly with regolith. The organic binders are mixed with regolith and small amounts of water to create printable structural “inks,” and experimental projects have demonstrated their feasibility in 3D-printed formulations;

ESA, in collaboration with Foster + Partners, even designed inflatable habitats shielded by 3D-printed regolith shells for enhanced radiation and meteorite protection.  The process involves an automated robotic arm that deposits layers of this composite material to form a structural shell over an inflatable module, designed to provide protection against radiation and micrometeorites;

Although 3D printing with regolith reduces Earth-bound material needs and enables autonomous construction, it still requires binders and water resources that are expensive to deliver and complex to manage under lunar conditions