  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.
