■ Students involved
Sukwon Youn (grasshoppe5@snu.ac.kr)
Dahye Ahn (rundahye@snu.ac.kr)
■ Description
In order to enable human space exploration missions, it is essential to understand the radiation environment and evaluate its biological effects. The space radiation environment can be classified into three major components: galactic cosmic rays (GCRs), solar energetic particles (SEPs), and trapped particles in the planetary radiation belt. GCRs consist of high-energy protons and heavy ions. Although their flux is relatively low, they can cause significant damage to spacecraft and human tissues due to their high energy and large linear energy transfer (LET). SEPs are mainly composed of energetic protons and can cause intense, short-term radiation exposure during solar particle events, leading to significant acute dose risks for astronauts. Trapped particles include energetic protons and electrons, which can pose potential hazards to spacecraft in low-Earth orbit (LEO).
We are modeling the space radiation environment and evaluating the biological effects using beam tests and Monte Carlo particle transport simulations. The radiation environments in LEO and on the lunar surface, along with detector responses, are simulated using various space radiation environment models. In addition, based on measurement data from particle dosimeters onboard the Low-Earth Orbit Space Radiation Dosimeter (LEO-DOS) science payload, we have analyzed variations in the LEO space radiation environment due to solar activity and assessed their biological impact.
Lunar Vehicle Radiation Dosimeter (LVRAD), which is being developed to measure the radiation environment and evaluate its biological effects on the lunar surface, incorporates multiple radiation detectors designed to characterize charged particle radiation and its impact on human health. The Tissue Equivalent Dosimeter (TED) is a particle dosimeter in which a silicon sensor is surrounded by tissue-equivalent plastic, enabling direct measurement of the biological effects of charged particles on the lunar surface. The Advanced Particle Dosimeter and Spectrometer (APDS) employs a silicon sensor and a CsI scintillator telescope configuration, allowing simultaneous measurement of the LET spectrum and the energy spectrum of protons, which are dominant in space.
In addition, neutron measurement instruments, including Fast Neutron Spectrometer (NS-F) and Epithermal Neutron Spectrometer (NS-E), are used to analyze neutron energy distributions and assess their biological impact. NS-F focuses on fast neutron measurements to evaluate their contribution to human radiation exposure, while NS-E measures thermal and epithermal neutron fluxes and performs gamma-ray spectroscopy, enabling the investigation of water ice evidence and the elemental composition of the lunar surface, which are essential for human exploration and in-situ resource utilization (ISRU).
