Shape, Structure and Material Compliance with Radiation Protection Requirements for Extraplanetary Modules

This research aims to explore a design solution for an innovative extraplanetary module that combines architectural design, structure and radiation protection for sustaining human life on Mars. The WATER (Water shielded Architectural Tree for Extraplanetary Resiliency) module is designed in order to increment the use of local resources (In Situ Resources Utilization) and robotic fabrication techniques for remote construction before human arrival on Mars. The key element of the design is the water that can be extracted from the substrate of the Martian regolith. Water plays an essential role in both in supporting life and protecting humans inside the habitat. Because of the reduced gravity and the fine atmosphere, the major load that a structure has to withstand on Mars is the internal pressurization. To balance that load and have a more efficient foundation system, the structure needs to be covered by a thick layer of water that is also extremely important for shielding against the harmful cosmic radiation. In fact, it is well known that a major threat to extraplanetary exploration is given by high energy cosmic particles and gamma fluxes. This work deals with the radiation protection constraints that should be considered for the WATER module, designed as an optimized possible long term habitat for Mars. The main materials considered for the module are the Martian regolith and, with respect to radiation shielding, the water that will be driven to fill the layer between the external and internal surfaces that will sustain the exposed external structures. The simulations, carried out with a standard Monte Carlo code like MCNPX and MCNP6, that is able to directly analyze the mesh geometries coming from the WATER module structural Finite Element model, define the optimal conditions in terms of shielding thickness and layer’s material composition. As output of the analysis, expositions and doses, that the inhabitants of these future architecture should bear, have been obtained. The final shielding configuration is integrated in the Finite Element model of the project for the structural analysis. The results prove that the water content, subjected to the Martian gravity, helps reducing the tensile stresses inside the structure due to the internal pressurization.