Chapter 5
Thermal Control Technology of Lunar
Lander
5.1 Introduction
Compared with Earth orbit and circumlunar spacecraft, lunar soft-landing probes
will go through complicated phases including launching, LTO, lunar orbit, powered
descent, landing and operation on lunar surface. The external environment and operation modes of instruments in different phases are different. It’s necessary to take
proper thermal control measures to make sure appropriate temperature range of structure and instruments to achieve mission objectives. The major function of thermal
control subsystem is to maintain the structure and instruments of the lunar lander
within acceptable temperature range throughout lifetime by controlling the heat
exchange between interior of the lunar lander and external environment with thermal
material and devices. The requirements of mass and power consumption of thermal
control subsystem shall be as low as possible. The temperature range is different, for
example, general electronic equipment is from −20 °C to 55 °C and inner structure
of the lunar lander is from −100 °C to 80 °C before landing. Therefore, there will
different thermal measures for different temperature range.
The environment is harsh during powered descent and operation on lunar surface
for the lunar lander. The structure of the lunar lander shall be far away from the descent
engine, whose nozzle temperature would be as higher as 1300 °C during powered
descent, in order to avoid higher temperature of structure and instruments near the
engine. It is important to take measures to insulate the structure and instruments
from the high temperature of descent engine. During the lunar daytime, the highest
temperature might be as high as 120 °C on lunar equator, while it might be as low as −
180 °C in lunar night for about 14 earth days [1]. The thermal control subsystem shall
adapt to the extreme high and low temperature alternation between lunar daytime
and night. Compare with the microgravity in LTO and lunar orbit, there will be 1/6 g
gravity on lunar surface, which will affect operation of heat pipes and two-phase
liquid loop. The simulation of the lunar 1/6 g gravity on earth is a challenge as well.
On the other side, the gravity on lunar surface makes it possible to transfer heat in
new method for thermal control.
© National Defense Industry Press and Springer Nature Singapore Pte Ltd. 2021
D.-Y. Yu et al., Technology of Lunar Soft Lander, Space Technology Library 38,
https://doi.org/10.1007/978-981-15-6580-9_5
151
Thermal Control Technology of Lunar
Lander
5.1 Introduction
Compared with Earth orbit and circumlunar spacecraft, lunar soft-landing probes
will go through complicated phases including launching, LTO, lunar orbit, powered
descent, landing and operation on lunar surface. The external environment and operation modes of instruments in different phases are different. It’s necessary to take
proper thermal control measures to make sure appropriate temperature range of structure and instruments to achieve mission objectives. The major function of thermal
control subsystem is to maintain the structure and instruments of the lunar lander
within acceptable temperature range throughout lifetime by controlling the heat
exchange between interior of the lunar lander and external environment with thermal
material and devices. The requirements of mass and power consumption of thermal
control subsystem shall be as low as possible. The temperature range is different, for
example, general electronic equipment is from −20 °C to 55 °C and inner structure
of the lunar lander is from −100 °C to 80 °C before landing. Therefore, there will
different thermal measures for different temperature range.
The environment is harsh during powered descent and operation on lunar surface
for the lunar lander. The structure of the lunar lander shall be far away from the descent
engine, whose nozzle temperature would be as higher as 1300 °C during powered
descent, in order to avoid higher temperature of structure and instruments near the
engine. It is important to take measures to insulate the structure and instruments
from the high temperature of descent engine. During the lunar daytime, the highest
temperature might be as high as 120 °C on lunar equator, while it might be as low as −
180 °C in lunar night for about 14 earth days [1]. The thermal control subsystem shall
adapt to the extreme high and low temperature alternation between lunar daytime
and night. Compare with the microgravity in LTO and lunar orbit, there will be 1/6 g
gravity on lunar surface, which will affect operation of heat pipes and two-phase
liquid loop. The simulation of the lunar 1/6 g gravity on earth is a challenge as well.
On the other side, the gravity on lunar surface makes it possible to transfer heat in
new method for thermal control.
© National Defense Industry Press and Springer Nature Singapore Pte Ltd. 2021
D.-Y. Yu et al., Technology of Lunar Soft Lander, Space Technology Library 38,
https://doi.org/10.1007/978-981-15-6580-9_5
151