6.2 Status of Power Supply Technology Development
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on lunar surface lasted for one day. After life-off on lunar surface, the ascent stage
of lunar module rendezvoused and docked with service and command modules.
Then service and command modules returned to Earth. When approaching Earth,
the command module with astronauts was separated and landed on Earth. The lunar
module had independent power supply requirement during LTO, landing, operation
on lunar surface, lift-off on lunar surface and docking with command module. The
command module had independent power supply requirement after separated with
service module and during return to Earth. The lunar module and command module
would not work independently for a long-term and requirement for electric power
was not large. The flight time of Apollo spacecraft with service module, command
module and lunar module was about 14 days. The average power consumption was
2 kW and the total energy consumption was 672 kW•h. There was no solar photovoltaic system in Apollo spacecraft. Instead, battery packs were used. During LTO,
the spacecraft was not influenced by the sun light. At the same time, the air drag of
very thin atmosphere could be avoided because there was no large area solar array on
the spacecraft so as to save propellant for engine firing. There were two main buses
in the spacecraft. The two main buses could be powered independently or jointly.
The three fuel cells could be flexibly combined to supply power to two main buses.
The secondary load on the spacecraft was powered by a secondary main bus. The
secondary load could be shut off by disconnecting the secondary main bus from the
main buses. Such power distribution method could effectively isolate fault battery
and enhance the power distribution capability. The power system design of the Apollo
spacecraft is determined by the electrical energy required for each mission segment.
The type of battery and its capacity were different in different mission phases. The
composition of power system is listed as follows:
(1) Service module. There were three 100 kg fuel cells to provide total power
570 kW•h and a cadmium-nickel battery pack could assist power supply for
peak power.
(2) Command module. There were three rechargeable cadmium-nickel battery
packs with a total capacity of 3.5 kW•h to power command module when it
returned to Earth. If necessary, it could be connected with the service module
battery for joint work and be charged by the fuel cells.
(3) Lunar Module: There were two zinc-silver storage batteries with a total power
of 8.4 kW•h to power lunar module when it left the Moon. There were four
zinc-silver batteries with a total energy of 46 kW•h for landing and operation
on lunar surface.
The combination of silicon solar array and nickel-hydraulic battery were used in
power systems of the Chang’E-1 [5] and the Chang’E-2 adopt. The peak output
power was higher than 2 kW. The triple junction GaAs solar array and lithium ion
battery were use in power system of the Chang’E-3 lunar lander, where the capacity
of lithium ion battery was 60Ah and peak output was less than 2 kW.
201
on lunar surface lasted for one day. After life-off on lunar surface, the ascent stage
of lunar module rendezvoused and docked with service and command modules.
Then service and command modules returned to Earth. When approaching Earth,
the command module with astronauts was separated and landed on Earth. The lunar
module had independent power supply requirement during LTO, landing, operation
on lunar surface, lift-off on lunar surface and docking with command module. The
command module had independent power supply requirement after separated with
service module and during return to Earth. The lunar module and command module
would not work independently for a long-term and requirement for electric power
was not large. The flight time of Apollo spacecraft with service module, command
module and lunar module was about 14 days. The average power consumption was
2 kW and the total energy consumption was 672 kW•h. There was no solar photovoltaic system in Apollo spacecraft. Instead, battery packs were used. During LTO,
the spacecraft was not influenced by the sun light. At the same time, the air drag of
very thin atmosphere could be avoided because there was no large area solar array on
the spacecraft so as to save propellant for engine firing. There were two main buses
in the spacecraft. The two main buses could be powered independently or jointly.
The three fuel cells could be flexibly combined to supply power to two main buses.
The secondary load on the spacecraft was powered by a secondary main bus. The
secondary load could be shut off by disconnecting the secondary main bus from the
main buses. Such power distribution method could effectively isolate fault battery
and enhance the power distribution capability. The power system design of the Apollo
spacecraft is determined by the electrical energy required for each mission segment.
The type of battery and its capacity were different in different mission phases. The
composition of power system is listed as follows:
(1) Service module. There were three 100 kg fuel cells to provide total power
570 kW•h and a cadmium-nickel battery pack could assist power supply for
peak power.
(2) Command module. There were three rechargeable cadmium-nickel battery
packs with a total capacity of 3.5 kW•h to power command module when it
returned to Earth. If necessary, it could be connected with the service module
battery for joint work and be charged by the fuel cells.
(3) Lunar Module: There were two zinc-silver storage batteries with a total power
of 8.4 kW•h to power lunar module when it left the Moon. There were four
zinc-silver batteries with a total energy of 46 kW•h for landing and operation
on lunar surface.
The combination of silicon solar array and nickel-hydraulic battery were used in
power systems of the Chang’E-1 [5] and the Chang’E-2 adopt. The peak output
power was higher than 2 kW. The triple junction GaAs solar array and lithium ion
battery were use in power system of the Chang’E-3 lunar lander, where the capacity
of lithium ion battery was 60Ah and peak output was less than 2 kW.