What is the energy of "home"?

In the orbit of hundreds of kilometers, the air is thin, the sun does not spread, the space background is dark, and the contrast is much larger than the ground. It will cause the astronauts' eyesight to drop and the instrument readings to be unclear. Secondly, when the spacecraft is in the dark, efficient incandescent lamps or other measures are needed to ensure the brightness in the cabin. In order to record the work and life of astronauts and the scenery in the cabin, photographic lights must also be placed in the cabin. Whether it is sunshine or light, effective measures should be taken in the cabin to make it soft and bright. In addition, in addition to lighting, many equipment and instruments in the spacecraft need electricity to start and keep running.

The power supply is the heart of the spacecraft, and its power supply is mainly solved by the following methods. One is a solar cell, which is a semiconductor device that can directly convert light energy into electric energy. It has a long life and can work continuously. As long as it faces the sun, the solar cell can work, providing electrical energy for instruments and equipment and charging the battery at the same time. When carrying the sun, the battery will take over the power supply from the solar cell. At present, there are two kinds of solar cell arrays: one is three-dimensional installation, that is, solar cells are directly installed on the hull of spacecraft; One is the expansion type, which separates the square array from the shell to form a separate assembly. When launching, it is fixed on the satellite body in a certain way, stored in the cover, and fully deployed after entering the orbit. Solar cells include silicon solar cells, gallium arsenide solar cells and cadmium sulfide solar cells. They are all connected in series and in parallel according to certain requirements. The United States once tested a flexible solar cell on the space shuttle Discovery, which spread out in the sky with an area of 3 1m×4m and a height of 10. This battery is made of Caplong film by printed circuit method, which can be unfolded and contracted like an accordion, and can be put into a small box of 18 cm after being folded. It can generate more than 12.5 kW of electric energy, which is slightly better than ordinary solar cells in performance, life and use. The second is fuel cell, which is an electrochemical device that converts the chemical energy of fuel into electrical energy. Its working principle is similar to that of a common battery, and it is also composed of two electrodes separated by a layer of electrolyte, which can generate electricity as well as electricity (described in the chapter on astronauts drinking water). Its types include ion exchange membrane hydroxide type, improved bacon type and asbestos membrane type. The rated power is 200 watts, 2000 watts and 5000 watts. During the seven-day mission of the space shuttle, one * * needs to consume 1627 kWh, which is mainly provided by three fuel cells. The minimum power of each battery is 34 watts, the average power is 7 kilowatts, and the maximum power is 12 kilowatts. The maximum power of the whole fuel cell is 24 kW, and the average power is 65,427 kW. Usually, only two fuel cells are used. According to the design requirements, the service life of the fuel cell is 5000 hours and the working life is 2000 hours. Each group of fuel cells can complete 29 7-day missions. Third, nuclear batteries have the characteristics of high power and long life. Nuclear batteries can be roughly divided into two categories: radioisotope power supply and nuclear reactor power supply, and the power is about 2-5 kilowatts. It is reported that the former Soviet Union has installed nuclear power sources on 33 marine surveillance and reconnaissance satellites launched. Nuclear power can bring stable power supply to satellites and spacecraft, and also bring anxiety to mankind. Over the past 30 years, many satellites of the former Soviet Union have failed, and their nuclear power plants have brought unbearable psychological pressure to the earth. They are often worried that nuclear disasters will fall from the sky. At present, the United States is developing a 20 kW space nuclear power source with a working life of 3-5 years to replace short-lived batteries.

No matter what kind of battery, its current should be distributed to all parts of the spacecraft that need electricity through the power distribution and control system, and the power demand of the spacecraft and its crew can be met through planned distribution to ensure the normal work and life of astronauts.

At present, the nuclear power generation technology of the space station is in the research stage. The Office of Strategic Defense Innovation of NASA, the Department of Energy and the Ministry of National Defense have formulated the "Self-Power Supply Plan 100", and it is estimated that the power consumption of the developing space station will exceed 300 kilowatts. Such a large amount of power supply can only be solved by nuclear power generation. Nuclear power generation equipment has three ideas. One is to install the reactor firmly on the space station, and the on-board system needs 38.5 to 49.5 tons of protective layer to prevent the damage of nuclear radiation, which means increasing the take-off weight of the space station. One is to hang the nuclear power plant on the space station with a long soft chain, which can reduce the weight of the protective layer, but the 30-kilometer-long chain hanging system will accelerate the space station and affect the weightless environment of related scientific experiments. One is a 200-kilometer-high free-flying platform. Its disadvantage is that this platform needs attitude control, energy and communication systems, and it is difficult to repair. Which method is feasible is still inconclusive. If nuclear power in space is successful, it will mark a new step for the space station.