![]() ![]() Galactic cosmic rays (GCR) are among the main deterrents to manned space exploration. Results from simulations show that the shielding properties are comparable to the neat polyethylene at low loadings (1–5 wt%) of filler, with the GO nanoplatelets being the best reinforcement for space radiation protection among the investigated fillers. Composites made of polyethylene and boron carbide particles were also analyzed for comparison with the carbon-filled composites. Simulations were performed for the case of galactic cosmic rays, solar particles events, and for the LEO radiation environment. The choice of polyethylene as the optimal matrix for radiation shielding was confirmed by preliminary studies on different aerospace-grade polymers, aluminium and liquid hydrogen. In particular, we analyze the role of single-walled carbon nanotubes (SWCNT) and graphene oxide (GO) nanoplatelets, at different loadings, on the equivalent dose absorbed by the nanocomposites in various radiation fields in space. In this study, we numerically investigate the radiation properties of polyethylene-based nanocomposites for space protection using the HZETRN2015 code by NASA. However, the effects of carbon nanoparticles on the nanocomposite radiation shielding performance in space are rather unknown. Doping polyethylene matrix with nanoparticles, such as carbon nanotubes and graphene, can significantly enhance the mechanical, electrical and thermal properties of this polymer. At the moment, polyethylene layers offer the most effective protection against high-energy charged particles in space, yet this material is mainly used in non-structural applications due to its poor mechanical properties. Current materials show many limitations in this regard and their applications in crew exploration vehicles, spacesuits and human habitats need further technological advancement. Human space missions beyond near Earth orbit require mitigating risk factors associated with radiation exposure. Verification of shield concepts requires results from specific designs to be compared with onboard dosimetry. These results suggest that shielding design and risk analysis are necessary measures for reducing long-term radiological risks to ISS inhabitants and for meeting legal ALARA requirements. Results of the studies shown herein indicate that 20% or more reduction in equivalent dose to the CQ occupant is achievable. Optimization of shield designs relies on accurate characterization of the expected primary and secondary particle environment and modeling of the predicted radiobiological responses of critical organs and tissues. Several designs for placement of slabs or walls of polyethylene have been evaluated for radiation exposure reduction in the Crew Quarters (CQ) of the Zvezda (Star) Service Module. Polyethylene (CnHn) is a relatively inexpensive, stable, and, with a low atomic number, an effective shielding material that has been certified for use aboard the ISS. Judicious placement of efficient shielding materials in locations where crewmembers sleep, rest, or work is an important means for implementing ALARA for spaceflight. ![]() Even with the expectation that regulatory dose limits will not be exceeded during a single tour of duty aboard the ISS, the "as low as reasonably achievable" (ALARA) precept requires that radiological risks be minimized when possible through a dose optimization process. With 5-7 month long duration missions at 51.6 degrees inclination in Low Earth Orbit, the ionizing radiation levels to which International Space Station (ISS) crewmembers are exposed will be the highest planned occupational exposures in the world. ![]()
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