Risk analysis of astronauts radiation dose induced by solar proton event
Solar proton event(SPE)is the major concern for astronauts in space radiation environment.With the coming of solar activity peak of the 25th solar cycle,the frequency of occurrence of solar proton event is increasing,as well as the intense of the events.Two SPEs of the most flux in March 23rd,2024 and June 8th,2003 and one with extra-large geomagnetic storm in May 10th,2004 were used to analysis the astronaut dose both in China Space Station orbit and lunar environment.First,radiation particle spectrum outside TianHe module was used to calculate astronauts dose inside the station,which was compared with the measured dose;second,the fitting result of proton spectrum from GOES16 satellite was used to calculate astronaut dose in lunar orbit,which was compared with the dose measured by CRaTER.Besides,the change of dose with extra shield of different material was calculated.The results indicate when no extra-large geomagnetic storm occurs,middle level SPE has no influence to astronaut in station,but an obvious dose increase happens in lunar environment,approaching ten or more mGy in skin.When shielded by Al or water of 10g/cm2,the astronaut's dose could be reduced to mGy or below.Extra energetic protons would observe on station orbit when an SPE with extra-large geomagnetic storm occurs,however when the amount of energetic protons is small,the extra dose is about several 1 nGy to 1 μGy in skin,which was negligible compared with daily dose.When a middle or above level SPE occurs,the influence to astronaut in LEO needs judge immediately,which is mostly based on the geomagnetic activity,but extra shield are needed for manned lunar exploration to ensure astronaut safety.
solar proton eventspace radiationlow earth orbitmanned lunar exploration
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