Risks of space radiation exposure to exploration astronauts: limitations in predictions based on the ground experiments and possible solutions

Future expeditions into interplanetary space, and in particular to the Moon and Mars, will expose astronauts to very high levels of cosmic radiation, which are known due to years of research and instruments that have been sent to space. It is, however, a limitation in understanding the risks of this radiation for the human body due to difficulties in simulating the complex space environment on Earth or complex human phantom and the inability to extrapolate human clinical outcomes based on animal models or simulation results. 
As human spaceflight continues on its path to success, we need to develop appropriate and effective mitigation strategies for future missions to improve our understanding of the space radiation risk by identifying the constraints of radiation research on the Earth and finding possible solutions based on the existing technologies to be closer to the reality as much as possible and better understand human physiology in space.  
As part of this paper, we have identified several factors that hinder our understanding of radiation risks for human crews and have identified ways to cope with these restrictions for a better understanding and preparation for human spaceflights in the future.