  In order for off-Earth top surface structures built from regolith to protect
astronauts from radiation, they need to be several meters thick. Technical
University Delft (TUD) proposes to excavate into the ground to create
subsurface habitats. By excavating not only natural protection from radiation
can be achieved but also thermal insulation because the temperature is more
stable underground. At the same time through excavation valuable resources can
be mined for through in situ resource utilization (ISRU). The idea is that a
swarm of autonomous mobile robots excavate the ground in a sloped downwards
spiral movement. The excavated regolith will be mixed with cement, which can be
reproduced on Mars through ISRU, in order to create concrete. The concrete is
3D printed/sprayed on the excavated tunnel to reinforce it. As soon as the
tunnels are reinforced, the material in-between the tunnels can be removed in
order to create a larger cavity that can be used for inhabitation. Proposed
approach relies on Design-to-Robotic-Production (D2RP) technology developed at
TUD1 for on-Earth applications. The rhizomatic 3D printed structure is a
structurally optimized porous shell structure with increased insulation
properties. In order to regulate the indoor pressurised environment an
inflatable structure is placed in the 3D printed cavity. This inflatable
structure is made of materials, which can also be at some point reproduced on
Mars through ISRU. Depending on location the habitat and the production system
are powered by a system combining solar and kite power. The ultimate goal is to
develop an autarkic D2RP system for building subsurface autarkic habitats on
Mars from locally obtained materials.
