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5 Thermal Control Technology of Lunar Lander
(5) Minimizing effects of lunar dust deposition on performance of thermal control
products. Thermal performance of OSR (Optical Sun Reflector) heat dissipation surfaces, thermal coatings such as white paint was greatly affected by lunar
dust. However, there was no simple and effective method to eliminate lunar
dust on lunar surface. The system prevention could help to prevent adverse
effects of lunar dust on thermal control products during landing by shut off of
landing engine before landing and shielding. There should be enough margins
for temperature of instruments in thermal design. In addition, the effect of
lunar dust on thermal control products such as OSR heat dissipation surface
and white paint should be verified by simulated lunar dust if possible.
(6) Consideration of the effect of engine’s high temperature on the lunar lander.
The thrust generated by engines was used by the lunar lander to perform lunar
orbit insertion, soft-landing and attitude control. Usually there were number
of engines in the lunar lander. When an engine was firing, the temperature
of engine nozzle was very high, while the velocity and heat flux of its plume
was also high, which had a great influence on the temperature of structure of
the lunar lander and instruments. When the configuration of the lunar lander
was designed, the engine should be exposed as much as possible to reduce
its influence on the lunar lander. In addition, high temperature thermal shields
and other products should be designed to protect the lunar lander by thermal
insulation of high-temperature engine.
5.4.2 Design of Thermal Control
1. Thermal Control Measures
There are passive and active measures in thermal control design of spacecraft. Passive
thermal control measures are used when the change of internal heat source and
external heat flux is small, or when the allowable temperature range of structure and
instruments is relatively wide. By selecting materials with different thermophysical
properties and controlling the heat exchange process between internal and external
reasonably, the temperature of structure and instruments can be controlled within the
allowable range. Passive thermal control measures are simple, highly reliable and
long life because there are no moving parts, which are generally used as the preferred
measures and basic measures for thermal control design of spacecraft. There are
thermal control coatings, multilayer thermal insulation materials, heat pipes, thermal
conductive fillers and thermal insulation pads in passive thermal control products.
When the internal heat source or external heat flow of spacecraft varies greatly,
or the temperature requirements of structure and instruments are within a narrow
range, passive thermal control measures cannot meet the requirements alone. Then
the active thermal control measures shall be added. Active thermal control measures
can adjust working conditions according to changes in the spacecraft environment
and keep the temperature of structure and instruments within the required range. Such
thermal control system has strong adaptability, but the system is more complex, while
5 Thermal Control Technology of Lunar Lander
(5) Minimizing effects of lunar dust deposition on performance of thermal control
products. Thermal performance of OSR (Optical Sun Reflector) heat dissipation surfaces, thermal coatings such as white paint was greatly affected by lunar
dust. However, there was no simple and effective method to eliminate lunar
dust on lunar surface. The system prevention could help to prevent adverse
effects of lunar dust on thermal control products during landing by shut off of
landing engine before landing and shielding. There should be enough margins
for temperature of instruments in thermal design. In addition, the effect of
lunar dust on thermal control products such as OSR heat dissipation surface
and white paint should be verified by simulated lunar dust if possible.
(6) Consideration of the effect of engine’s high temperature on the lunar lander.
The thrust generated by engines was used by the lunar lander to perform lunar
orbit insertion, soft-landing and attitude control. Usually there were number
of engines in the lunar lander. When an engine was firing, the temperature
of engine nozzle was very high, while the velocity and heat flux of its plume
was also high, which had a great influence on the temperature of structure of
the lunar lander and instruments. When the configuration of the lunar lander
was designed, the engine should be exposed as much as possible to reduce
its influence on the lunar lander. In addition, high temperature thermal shields
and other products should be designed to protect the lunar lander by thermal
insulation of high-temperature engine.
5.4.2 Design of Thermal Control
1. Thermal Control Measures
There are passive and active measures in thermal control design of spacecraft. Passive
thermal control measures are used when the change of internal heat source and
external heat flux is small, or when the allowable temperature range of structure and
instruments is relatively wide. By selecting materials with different thermophysical
properties and controlling the heat exchange process between internal and external
reasonably, the temperature of structure and instruments can be controlled within the
allowable range. Passive thermal control measures are simple, highly reliable and
long life because there are no moving parts, which are generally used as the preferred
measures and basic measures for thermal control design of spacecraft. There are
thermal control coatings, multilayer thermal insulation materials, heat pipes, thermal
conductive fillers and thermal insulation pads in passive thermal control products.
When the internal heat source or external heat flow of spacecraft varies greatly,
or the temperature requirements of structure and instruments are within a narrow
range, passive thermal control measures cannot meet the requirements alone. Then
the active thermal control measures shall be added. Active thermal control measures
can adjust working conditions according to changes in the spacecraft environment
and keep the temperature of structure and instruments within the required range. Such
thermal control system has strong adaptability, but the system is more complex, while