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5 Thermal Control Technology of Lunar Lander
emergencies handling. If it was necessary, the flight procedure of the lunar lander
could be modified to meet temperature requirements. According to past experience,
correction of thermal analysis model should focus on heat capacity of instruments
and structure, heat conduction among different components, heat consumption and
operation modes of instruments.
5.5 Typical Technologies
The environment experienced by the lunar lander such as lunar orbit insertion,
landing, lunar surface after landing was quite different from other spacecrafts. In
order to meet the mission requirements, the thermal control subsystem should adopt
several typical technologies suitable for the lunar lander including variable thermalconductive technology, high-temperature protection technology for engines, RHU
application technology and two-phase fluid loop technology.
5.5.1 Variable Thermal Conductive Technology
According to the task analysis, the external heat flow in different phase and the operating modes of instruments varied greatly. For conventional heat transfer components
of constant thermal conductivity such as conventional heat pipes, there would be relatively large fluctuation of instrument temperature. If a variable thermal conductivity
product such as a variable conductive heat pipe is applied, the length of its working
period could be automatically adjusted according to the operating mode of instrument
and the external heat flow to reduce temperature fluctuation of instrument.
The lunar lander should dissipate heat in lunar day time and keep the instrument
module warm in lunar night. Such requirements could only be achieved by variable
thermal conductivity technology at the same time. The relation between the lunar
lander structure and heat transfer system of variable thermal conductivity is shown
in Fig. 5.10.
There were available variable thermal conductivity technologies including VCHP,
LHP, pump-driving two-phase fluid loop and heat pipes of special fluids, where
VCHP and LHP technologies were more mature. For heat pipes of special fluids, the
fluids of different freezing points were selected to work at the required temperature
in gas and liquid phase. When the temperature was below freezing point, the fluid is
frozen to solid and the heat pipe stops working to block the heat transfer. For specific
applications, two or more variable thermal conductivity products could be combined
and used at the same time. It could be evaluated by power requirement, mass, lifetime,
technology readiness, inheritance, complexity, and experimental feasibility to choose
the most suitable product for mission requirements.
The rationale of the VCHP with gas tank on cold side is shown in Fig. 5.11.
Compared with the conventional heat pipe, there was an additional gas tank with
5 Thermal Control Technology of Lunar Lander
emergencies handling. If it was necessary, the flight procedure of the lunar lander
could be modified to meet temperature requirements. According to past experience,
correction of thermal analysis model should focus on heat capacity of instruments
and structure, heat conduction among different components, heat consumption and
operation modes of instruments.
5.5 Typical Technologies
The environment experienced by the lunar lander such as lunar orbit insertion,
landing, lunar surface after landing was quite different from other spacecrafts. In
order to meet the mission requirements, the thermal control subsystem should adopt
several typical technologies suitable for the lunar lander including variable thermalconductive technology, high-temperature protection technology for engines, RHU
application technology and two-phase fluid loop technology.
5.5.1 Variable Thermal Conductive Technology
According to the task analysis, the external heat flow in different phase and the operating modes of instruments varied greatly. For conventional heat transfer components
of constant thermal conductivity such as conventional heat pipes, there would be relatively large fluctuation of instrument temperature. If a variable thermal conductivity
product such as a variable conductive heat pipe is applied, the length of its working
period could be automatically adjusted according to the operating mode of instrument
and the external heat flow to reduce temperature fluctuation of instrument.
The lunar lander should dissipate heat in lunar day time and keep the instrument
module warm in lunar night. Such requirements could only be achieved by variable
thermal conductivity technology at the same time. The relation between the lunar
lander structure and heat transfer system of variable thermal conductivity is shown
in Fig. 5.10.
There were available variable thermal conductivity technologies including VCHP,
LHP, pump-driving two-phase fluid loop and heat pipes of special fluids, where
VCHP and LHP technologies were more mature. For heat pipes of special fluids, the
fluids of different freezing points were selected to work at the required temperature
in gas and liquid phase. When the temperature was below freezing point, the fluid is
frozen to solid and the heat pipe stops working to block the heat transfer. For specific
applications, two or more variable thermal conductivity products could be combined
and used at the same time. It could be evaluated by power requirement, mass, lifetime,
technology readiness, inheritance, complexity, and experimental feasibility to choose
the most suitable product for mission requirements.
The rationale of the VCHP with gas tank on cold side is shown in Fig. 5.11.
Compared with the conventional heat pipe, there was an additional gas tank with