10:45 AM - 12:15 PM
[AOS14-P03] Study on shielding of space radiation in lunar structures using watery material
Keywords:Radiation exposure, Lunar base
There are various barriers to the advancement of manned space missions, and cosmic radiation exposure is one of the most significant issues. In this study, for the objective of tackling the radiation issues for human space activity and in anticipation of the full-scale start and construction of the lunar base, we present the estimates of radiation exposure to the simple lunar base.
Firstly, we modeled the dome-shaped base whose radius was 20m on the moon surface and simulated the radiation dose inside the base when a solar particle event (SPE) with the scale equivalent to that occurred in September 1989. In our study, the PHITS code was employed in the cosmic radiation transport simulation. We estimated the thickness of the wall that would result in radiation dose inside the base being lower than 50mSv specified for occupational exposure. The wall materials are (1) water + polyethylene, (2) magnesium alloy, AZ91D and AZ31, (3) aluminum alloy, A7204, and (4) combinations of each alloy. The results showed that the thickness of the wall should be approximately 8 - 20 g/cm2, depending on the material.
We also calculated the cost of transportation from the information of more than 100 million yen/kg to transport from the earth’s ground to the moon’s surface. The transportation cost would be more than 45 trillion yen each if all the above wall materials were to be transported from the earth.
From this study, it can be concluded that it is unrealistic to construct a lunar base that can sufficiently shield the cosmic-radiation exposure due to SPE using the materials only transported from the earth. Thus, it is necessary to effectively utilize lunar surface resources in addition to transportation from the ground.
Firstly, we modeled the dome-shaped base whose radius was 20m on the moon surface and simulated the radiation dose inside the base when a solar particle event (SPE) with the scale equivalent to that occurred in September 1989. In our study, the PHITS code was employed in the cosmic radiation transport simulation. We estimated the thickness of the wall that would result in radiation dose inside the base being lower than 50mSv specified for occupational exposure. The wall materials are (1) water + polyethylene, (2) magnesium alloy, AZ91D and AZ31, (3) aluminum alloy, A7204, and (4) combinations of each alloy. The results showed that the thickness of the wall should be approximately 8 - 20 g/cm2, depending on the material.
We also calculated the cost of transportation from the information of more than 100 million yen/kg to transport from the earth’s ground to the moon’s surface. The transportation cost would be more than 45 trillion yen each if all the above wall materials were to be transported from the earth.
From this study, it can be concluded that it is unrealistic to construct a lunar base that can sufficiently shield the cosmic-radiation exposure due to SPE using the materials only transported from the earth. Thus, it is necessary to effectively utilize lunar surface resources in addition to transportation from the ground.