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2 Environment Analysis of Lunar Soft Landing Exploration
angular shape show up, while the rod-like, sub angular and angular shape appears
more frequently.
2. Density
Density of the unspoiled lunar soil is the mass of lunar soil in a unit volume. The
analysis of existing lunar soil sample shows that the relation between the density ρ
(g/cm
3 ) and depth z (cm) can be expressed as follows equation:
ρ= 1.92 ×
z + 12.2
z + 18
(2.7)
The analysis result of lunar soil density is shown in Fig. 2.12. In the depth 0~40 cm,
the range of the density of lunar soil is 1.3~1.7 g/cm
3 . The best estimation of the
average density of lunar soil in different depth of crater is listed in Table 2.6.
3. Porosity
Degree of porosity includes void ratio and porosity. The void ratio of lunar soil means
the ratio of the void volume and the particle volume and is denoted as e. The natural
void ratio of lunar soil may be used to evaluate the degree of compaction of lunar
soil. When e < 0.6, it is dense and low compressibility lunar soil. When e > 1.0, it
Fig. 2.12 The analysis result of lunar soil density
Table 2.6 The best
estimation of the average
density of lunar soil in
different depth of crater
Depth/cm
Average density/(g/cm 3 )
0~15
1.45~1.55
0~30
1.53~1.63
0~60
1.61~1.71
30~60
1.69~1.79