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2 Environment Analysis of Lunar Soft Landing Exploration
near vacuum environment of the Moon and the illumination law on lunar surface are
presented.
Lunar radiation environment mainly includes the solar cosmic ray, the galactic
cosmic ray and the solar wind. Since the distance from Earth to Moon is relatively
small comparing to the diurnal distance, the lunar radiation environment faced by
the lunar lander is similar to the radiation environment of spacecraft on Earth orbit.
The thermal environment of Moon is an important factor in the design of the
thermal control system of the lunar lander. It includes solar radiation, reflection of
sunlight by lunar surface, lunar radiation and terrestrial albedo. The value of solar
radiation, which is the majority of external heat flow, is equivalent to that for normal
spacecraft on Earth orbit. Lunar radiation is the secondary external heat flow, while
the external heat flow caused by terrestrial albedo usually can be ignored.
The landform and topography on lunar surface are the environment that requires
serious consideration in the lunar soft-landing mission. The lunar surface is generally
classified in two kinds of topography, i.e., the lunar mare and the highland. The lunar
mare and the highland are both covered by rocks and craters in different sizes and
shapes. The slopes, rocks and craters at landing site are important factors for safe
landing. Distribution of slope, rock and crater on the different topography of lunar
surface is presented.
Lunar soil is consisted of rock fragment, powder, breccia and impacting melting
glass. It is loose mixture that covers the lunar surface. Lunar dust is the small size
particle among the lunar soil, which is pretty loose and will be raised under certain
impact of force. The basic physicochemical properties of lunar dust are same with
those of lunar soil. This chapter discusses the physical property, the mechanical property and the electromagnetic property of lunar soil. These properties are the important
factors that affect the landing stability, the cushion capability, the navigation sensor
and the telecommunication on lunar surface of the lunar lander.
The last section of this chapter discusses the gravitational field, the near vacuum
space and the illumination of the Moon. The design of the lunar lander has to take
the 1/6 g gravity into consideration. The precise model of lunar gravitational field is
an important basis in the design of the lunar orbit and the guidance rule in powered
descent process. The vacuum degree on lunar surface is similar to that of near-Earth
orbit with an altitude range of 500~2500 km. The design of the lunar lander in the
material outgas, the evaporation, sublimation and decomposition of material, the
thermal design, the vacuum cold welding and dry friction and the vacuum discharge
of electronic devices is similar to the design of Earth spacecraft. One lunar day is
approximately 28 Earth days. Except the lunar night as long as 14 Earth days, shorttime invisibility of Sun may happen on the Moon due to the block of the Earth. Similar
to Earth, the elevation angle and the azimuth angle of Sun vary with the different
longitude and latitude of locations on the lunar surface. Besides, the rotational period
of the Moon is about 28 times of that of the Earth. Therefore, the rate of variation of
solar angle on lunar surface is about 1/28 of that of the Earth.
This chapter only analyzes the characteristics of the lunar natural environment.
The analysis of induced environment is not included and the effects of the induced
environment on the lunar lander are not discussed too.
2 Environment Analysis of Lunar Soft Landing Exploration
near vacuum environment of the Moon and the illumination law on lunar surface are
presented.
Lunar radiation environment mainly includes the solar cosmic ray, the galactic
cosmic ray and the solar wind. Since the distance from Earth to Moon is relatively
small comparing to the diurnal distance, the lunar radiation environment faced by
the lunar lander is similar to the radiation environment of spacecraft on Earth orbit.
The thermal environment of Moon is an important factor in the design of the
thermal control system of the lunar lander. It includes solar radiation, reflection of
sunlight by lunar surface, lunar radiation and terrestrial albedo. The value of solar
radiation, which is the majority of external heat flow, is equivalent to that for normal
spacecraft on Earth orbit. Lunar radiation is the secondary external heat flow, while
the external heat flow caused by terrestrial albedo usually can be ignored.
The landform and topography on lunar surface are the environment that requires
serious consideration in the lunar soft-landing mission. The lunar surface is generally
classified in two kinds of topography, i.e., the lunar mare and the highland. The lunar
mare and the highland are both covered by rocks and craters in different sizes and
shapes. The slopes, rocks and craters at landing site are important factors for safe
landing. Distribution of slope, rock and crater on the different topography of lunar
surface is presented.
Lunar soil is consisted of rock fragment, powder, breccia and impacting melting
glass. It is loose mixture that covers the lunar surface. Lunar dust is the small size
particle among the lunar soil, which is pretty loose and will be raised under certain
impact of force. The basic physicochemical properties of lunar dust are same with
those of lunar soil. This chapter discusses the physical property, the mechanical property and the electromagnetic property of lunar soil. These properties are the important
factors that affect the landing stability, the cushion capability, the navigation sensor
and the telecommunication on lunar surface of the lunar lander.
The last section of this chapter discusses the gravitational field, the near vacuum
space and the illumination of the Moon. The design of the lunar lander has to take
the 1/6 g gravity into consideration. The precise model of lunar gravitational field is
an important basis in the design of the lunar orbit and the guidance rule in powered
descent process. The vacuum degree on lunar surface is similar to that of near-Earth
orbit with an altitude range of 500~2500 km. The design of the lunar lander in the
material outgas, the evaporation, sublimation and decomposition of material, the
thermal design, the vacuum cold welding and dry friction and the vacuum discharge
of electronic devices is similar to the design of Earth spacecraft. One lunar day is
approximately 28 Earth days. Except the lunar night as long as 14 Earth days, shorttime invisibility of Sun may happen on the Moon due to the block of the Earth. Similar
to Earth, the elevation angle and the azimuth angle of Sun vary with the different
longitude and latitude of locations on the lunar surface. Besides, the rotational period
of the Moon is about 28 times of that of the Earth. Therefore, the rate of variation of
solar angle on lunar surface is about 1/28 of that of the Earth.
This chapter only analyzes the characteristics of the lunar natural environment.
The analysis of induced environment is not included and the effects of the induced
environment on the lunar lander are not discussed too.