Lunar Radiation Dose due to Cosmic Rays and Their Secondary Particles

Paper number

IAC-10.A1.4.6

Author

Ms. Kanako Hayatsu, Waseda University, Japan

Coauthor

Dr. Yuzuru Karouji, Waseda University, Japan

Coauthor

Prof. Lembit Sihver, Chalmers University of Technology, Sweden

Coauthor

Prof. Nobuyuki Hasebe, Waseda University, Japan

Year

2010

Abstract

The current decade has seen a revival in the field of planetary exploration with several initiatives to explore the some solar system objects. A new effort to explore the Moon has started in 2007 with the Japan’s large-scaled lunar explorer, SELENE (KAGUYA), for the first time followed by China, India and USA. Moreover, many lunar missions are being developed by several countries within a coming few years. Future plans for a permanently manned base on the Moon have been initiated. In such a situation, the clear evaluation of the radiation environment is a matter of great urgency for the safety of the astronauts. 
Radiation environment on the Moon is much different from that on the Earth. Galactic cosmic rays (hereafter, GCRs) and solar energetic particles (hereafter, SEPs) directly arrive at the lunar surface because of no atmosphere and no magnetic field around the Moon. Then, they generate many secondary particles such as neutrons and gamma rays by nuclear interactions with soils under the lunar surface. Therefore, the estimation of radiation dose from them on the surface and the underground of the Moon are essential for the safeness of human activities.
In this study, the effective dose equivalents at the surface and various depths of the Moon were estimated using by the latest cosmic rays observation and the calculation code newly developed for the Moon. The largest contribution to the dose on the surface is primary charged particles in GCRs and SEPs, while in the ground, secondary neutrons are the most dominant. Particularly, on the lunar surface, the doses originated from large SEPs are very hazardous. We estimated the effective dose equivalents due to such large SEPs and the effects of aluminum shield on the human body. These results will provide useful data for the future exploration of the Moon.

Abstract document

IAC-10.A1.4.6.brief.pdf

Manuscript document

IAC-10.A1.4.6.pdf (🔒 authorized access only).

To get the manuscript, please contact IAF Secretariat.