2.3 Lunar Thermal Environment
27
Table 2.3 Nominal albedo of
lunar surface
Regions on the Moon
Nominal Albedo
Min
Max
Average
Dark region
0.07
0.12
0.095
Upland region
0.108
0.24
0.150
“Lunar Surface Models, NASA Space Vehicle Design Criteria (Environment)” of
NASA. Based on the data from this criterion, a certain margin in mission design is
required to offset the uncertainty and limitation. The nominal albedo of lunar surface
given by the design criterion SP-8023 of NASA is shown in Table 2.3.
2.3.3 Lunar Radiation
The infrared radiation of lunar surface is one of the heat sources for the lunar lander.
Lunar radiation data is also given in the design criterion SP-8023 of NASA: In a unit
area with average albedo of 0.110, the thermal radiation from lunar surface is about
310 W/m
2 .
Based on the “Explorer” A-21A model, the infrared emissivity of Moon ε = 0.875
and the sunlight absorptivity = 0.93. These data can be applied in design of the lunar
lander.
2.3.4 Earth Albedo
For lunar landers having orbiting Earth phases, heat flux from Earth albedo should
be considered in thermal analysis. The heat flux density of Earth albedo varies with
the surface morphology of Earth, the season, the geographical latitude and the orbit
inclination. However, the flight altitude and speed of the lunar lander are high, and
the energy of Earth albedo is relatively low compared to the energy of direct radiation
from Sun. Therefore, an average albedo of 0.35 is usually used in the thermal analysis.
2.3.5 Earth Radiation
For the lunar lander passing the Earth, heat flux from Earth radiation should be
considered in thermal analysis. The heat flux density of Earth radiation varies with the
surface morphology of Earth, the season, the climate and the geographical latitude.
In thermal analysis, an average value is usually used. The average infrared heat flux
density of Earth is about 220 W/m
2 .
27
Table 2.3 Nominal albedo of
lunar surface
Regions on the Moon
Nominal Albedo
Min
Max
Average
Dark region
0.07
0.12
0.095
Upland region
0.108
0.24
0.150
“Lunar Surface Models, NASA Space Vehicle Design Criteria (Environment)” of
NASA. Based on the data from this criterion, a certain margin in mission design is
required to offset the uncertainty and limitation. The nominal albedo of lunar surface
given by the design criterion SP-8023 of NASA is shown in Table 2.3.
2.3.3 Lunar Radiation
The infrared radiation of lunar surface is one of the heat sources for the lunar lander.
Lunar radiation data is also given in the design criterion SP-8023 of NASA: In a unit
area with average albedo of 0.110, the thermal radiation from lunar surface is about
310 W/m
2 .
Based on the “Explorer” A-21A model, the infrared emissivity of Moon ε = 0.875
and the sunlight absorptivity = 0.93. These data can be applied in design of the lunar
lander.
2.3.4 Earth Albedo
For lunar landers having orbiting Earth phases, heat flux from Earth albedo should
be considered in thermal analysis. The heat flux density of Earth albedo varies with
the surface morphology of Earth, the season, the geographical latitude and the orbit
inclination. However, the flight altitude and speed of the lunar lander are high, and
the energy of Earth albedo is relatively low compared to the energy of direct radiation
from Sun. Therefore, an average albedo of 0.35 is usually used in the thermal analysis.
2.3.5 Earth Radiation
For the lunar lander passing the Earth, heat flux from Earth radiation should be
considered in thermal analysis. The heat flux density of Earth radiation varies with the
surface morphology of Earth, the season, the climate and the geographical latitude.
In thermal analysis, an average value is usually used. The average infrared heat flux
density of Earth is about 220 W/m
2 .