MISSION TO MARS: RADIATION SAFETY OR RADIATION DISASTER? SPACE TRANSIT AND MARS RADIATION EXPOSURE RISKS – THE POTENTIAL SHIELDING EFFECT OF AN INTRAVEHICULAR GRAPHENE SPACE SUIT AND A STORM SHELTER DURING SPACE TRAVEL

ABSTRACT Aim The purpose of this research was to employ radiobiological as well as physics principles to investigate materials for an intravehicular spacesuit and a “storm shelter” that might minimize radiation exposure to astronauts during a mission to Mars. Methods NASA’s OLTARIS space radiation modelling tool was used to investigate thirty-two potential shielding materials. Radiation exposure was estimated during a return transit to Mars of 360 days duration. We assessed each shielding material by its ability to decrease effective radiation dose received by a computerized phantom during the constant galactic cosmic radiation (GCR) and a single solar particle event (SPE). For the “storm shelter” a large liquid fuel tank was modelled adjacent to the phantom during a SPE. Results At standard conditions, graphene appeared to be a promising shielding material when comparing other materials including polyethylene and lithium. The shielding efficacy became comparable to polyethylene but inferior to lithium when materials were normalised to 10g/cm2, 20g/cm2 and 30g/cm2. The graphene around the phantom reduced effective dose from GCR compared with an unshielded transit by 34% (162mSv/yr vs 213.3mSv/yr). A “storm shelter” using a liquid fuel tank was positioned to create a barrier adjacent to the astronauts. The liquid barrier reduced effective dose by 98.8% (44mSv vs 3614mSv). Other mitigation strategies were deduced and divided into launch, transit and habitation considerations. Conclusion A graphene based intravehicular suit could decrease astronaut exposure to harmful radiation during transit to Mars. A storm shelter using fuel as a barrier also decreased radiation dose during a solar particle event.