摘要
The radiation environment on the surface of Mars is a potential threat for future manned exploration missions to this planet.In this study,a simple geometrical model was built for simulating the radiation environment on the Mars surface caused by galactic cosmic rays;the model was built and studied using the Geant4 toolkit.The simulation results were compared with the data reported by a radiation assessment detector(RAD).The simulated spectra of neutrons,photons,protons,α particles,and particle groups Z=3-5,Z=6-8,Z=9-13,and Z=14-24 were in a reasonable agreement with the RAD data.However,for deuterons,tritons,and 3He,the simulations yielded much smaller values than for the corresponding RAD data.In addition,the particles’spectra within the 90 zenith angle were also obtained.Based on these spectra,we calculated the radiation dose that would have been received by an average human body on Mars.The distribution of the dose throughout the human body was not uniform.The absorbed and equivalent doses for the brain were the highest among all of the organs,reaching 62.0±1.7 mGy/y and 234.1±8.0 mSv/y,respectively.The average absorbed and equivalent doses for the entire body were approximately 44 mGy/y and 153 mSv/y,respectively.Further analysis revealed that most of the radiation dose was owing to a particles,protons,and heavy ions.We then studied the shielding effect of the Mars soil with respect to the radiation.The body dose decreased significantly with increasing soil depth.At the depth of 1.5 m,the effective dose for the entire body was 17.9±2.4 mSv/y,lower than the dose limit for occupational exposure.At the depth of 3 m,the effective dose to the body was 2.7±1.0 mSv/y,still higher than the accepted dose limit.
基金
supported by the National Natural Science Foundation of China(Nos.12035011,11535004,11905103,11947211,11975167,11761161001,11565010,11961141003,11805103,11673075,11303107,11120101005,and 11235001)
the National Key R&D Program of China(Nos.2018YFA0404403 and 2016YFE0129300)
the Science and Technology Development Fund of Macao(No.008/2017/AFJ)
the Fundamental Research Funds for the Central Universities(Nos.22120210138 and 22120200101)
by the China Post-doctoral Science Foundation(Nos.2019M660095 and 2020T130478)。
