Radiobiological Foundation of Crew Radiation Risk for Mars Mission to the Problem of the Space Flight Safety

Abstract

This paper presents results of radiobiological experiments, a new concept of radiation hazard on the basis of a generalized dosimetric function, which are foundation of crew radiation risk for Mars mission. The results of 14-year biological experiment on comprehensive clinico-physiological study of 250 dogs exposure to gamma-radiation 60Co during 3 and 6 years 22 hours per day, modeling the impact of space radiation on the crew of a space shuttle flight to Mars are presented also. In this experiment dose and dose rate varied to simulate galactic cosmic ray (GCR) dose and dose from stochastic irradiation caused by solar cosmic rays (SCR). It details observations made on the animals throughout the course of the dogs’ lives, both during and eight years after radiation exposure. It includes data on dose dependence, threshold levels of radiation causing adverse health effects, as well as on the nature of radiation reactions as they develop in different organs and body systems chronically exposed to larger doses. This multi-year experiment was conducted by scientists of the State Research Center Institute of Biomedical Problems (Russian Academy of Sciences) with the active participation of the Institute of Biophysics (now Burnasyan Federal Medical Biophysical Center of Federal Medical Biological Agency). Based on results obtained in this study and in experiments realized with big amount of small laboratory animals that were exposed to a wide dose and dose rate range, using other published data, mathematical models were developed, e.g. a model of radiation damage forming as dependent on time with taking into account recovery processes, and model of radiation mortality rate of mammals. Based on these models and analysis of radiation environment behind various shielding on the route to Mars, crew radiation risk was calculated for space missions of various duration. Total radiation risk values for cosmonauts lifetime after the missions were also estimated together with expected life span reduction.