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2 Environment Analysis of Lunar Soft Landing Exploration
2.2 Lunar Radiation Environment
On lunar orbit or on lunar surface, the major sources of charged particles radiation
include the cosmic ray, the solar energetic particles and the plasma environment on
lunar orbit.
2.2.1 Galactic Cosmic Rays
The Galactic Cosmic Rays (GCRs) come from the interstellar space of the Milky
Way galaxy beyond the solar system. It is primarily composed of lower flux and
extremely high-energy protons and heavy ions. The energy of the GCRs particles is
generally ranging from 10
2 to 10
12 MeV, while the energy of the majority of particles
is between 10
3 MeV and 10
7 MeV. The free space flux of the particles is only 0.2~0.4
(cm
2 ·sr·s)
−1 . GCRs cover almost all the elements in periodic table of elements, while
the energy spectrum of the particles is different from each other. Among them, 84.3%
are protons, 14.4% are α particles and the rest 1.3% are the other heavy nuclei.
Due to the shielding effect of the interplanetary magnetic field on the GCRs,
the energy spectrum of the GCRs that reach the Earth space has a close relation
with intensity of interplanetary magnetic field. Since the solar activity affects on the
interplanetary magnetic field, it also affects the GCRs. Generally, there is negative
correlation between the intensity of the GCRs and the solar activity. The intensity of
cosmic ray reaches its minimum in a solar maximum year and reaches its maximum
in a solar minimum year.
2.2.2 Solar Energetic Particles
The solar particle events (also called the solar proton events since the most of particles
are proton) happens during the solar storm. It is a paroxysmal turbulent of radiation
environment and its intensity is related to the intensity and the position of solar burst
activity. Large number of high-energy particles (primarily protons) are ejected in
the solar burst activities (such as solar flare and coronal mass ejection). Due to the
effects of various acceleration mechanisms, the ions and electrons are accelerated to
a very high energy level from the lower layer of atmosphere of the Sun to the broad
interplanetary space. They travel to the Earth along the solenoid magnetic field of
the Sun under the effects of propagation and diffusion, which are eventually detected
by the spacecraft in the space and the particle monitor on the ground.
The solar energetic particles are composed of all the elements that exist in nature.
The basic properties of solar particle events are listed in Table 2.1. It is shown that
most of the solar high-energy particles are protons, and the rest are α particles and
a very small amount of heavy nuclei particles in Table 2.1. Although the proportion
2 Environment Analysis of Lunar Soft Landing Exploration
2.2 Lunar Radiation Environment
On lunar orbit or on lunar surface, the major sources of charged particles radiation
include the cosmic ray, the solar energetic particles and the plasma environment on
lunar orbit.
2.2.1 Galactic Cosmic Rays
The Galactic Cosmic Rays (GCRs) come from the interstellar space of the Milky
Way galaxy beyond the solar system. It is primarily composed of lower flux and
extremely high-energy protons and heavy ions. The energy of the GCRs particles is
generally ranging from 10
2 to 10
12 MeV, while the energy of the majority of particles
is between 10
3 MeV and 10
7 MeV. The free space flux of the particles is only 0.2~0.4
(cm
2 ·sr·s)
−1 . GCRs cover almost all the elements in periodic table of elements, while
the energy spectrum of the particles is different from each other. Among them, 84.3%
are protons, 14.4% are α particles and the rest 1.3% are the other heavy nuclei.
Due to the shielding effect of the interplanetary magnetic field on the GCRs,
the energy spectrum of the GCRs that reach the Earth space has a close relation
with intensity of interplanetary magnetic field. Since the solar activity affects on the
interplanetary magnetic field, it also affects the GCRs. Generally, there is negative
correlation between the intensity of the GCRs and the solar activity. The intensity of
cosmic ray reaches its minimum in a solar maximum year and reaches its maximum
in a solar minimum year.
2.2.2 Solar Energetic Particles
The solar particle events (also called the solar proton events since the most of particles
are proton) happens during the solar storm. It is a paroxysmal turbulent of radiation
environment and its intensity is related to the intensity and the position of solar burst
activity. Large number of high-energy particles (primarily protons) are ejected in
the solar burst activities (such as solar flare and coronal mass ejection). Due to the
effects of various acceleration mechanisms, the ions and electrons are accelerated to
a very high energy level from the lower layer of atmosphere of the Sun to the broad
interplanetary space. They travel to the Earth along the solenoid magnetic field of
the Sun under the effects of propagation and diffusion, which are eventually detected
by the spacecraft in the space and the particle monitor on the ground.
The solar energetic particles are composed of all the elements that exist in nature.
The basic properties of solar particle events are listed in Table 2.1. It is shown that
most of the solar high-energy particles are protons, and the rest are α particles and
a very small amount of heavy nuclei particles in Table 2.1. Although the proportion