Synthetic space bricks from lunar and martian regolith via sintering

The prospect of establishing extra-terrestrial habitats using in situ resource utilization (ISRU) constitutes a long-term goal of multiple space agencies around the world. In this work, we investigate sintering as a potential route for making building blocks -- termed synthetic space bricks -- using \emph{in situ} regolith material. By systematically investigating sintering parameters using a numerical lattice model, coupled with experimental observations and post sintering characterization, we propose a process protocol for two lunar -- lunar highland simulant (LHS) and lunar mare dust simulant (LMS) -- and one martian (martian global simulant, MGS) simulants. The resulting bricks demonstrate compressive strengths of upto 45 MPa under uniaxial loading, depending on the simulant used. These strengths are much greater than those typically mandated for structural applications under reduced gravity. We infer microscale sintering mechanisms at the individual particle level indirectly, by measuring temporal evolution exponents of sample dimensions during sintering. For all three simulants, volume diffusion appears to be the primary mechanism for particle coalescence. Our results clearly make a strong case for the use of sintering as a potentially scalable method for consolidating regolith into brick-like structures for load-bearing applications in extra-terrestrial settings.