What are the requirements for satellite launch?

Satellite launch is a complex system engineering, which needs the close cooperation and cooperation of all systems. It usually takes about 40 days from the arrival of rockets and satellites at the launch site to the launch. After a series of complicated processes, the star arrow was tested until it was launched. After the rockets and satellites arrive at the launch site, they should be assembled and tested in their respective test halls. The test hall is equipped with high-power air conditioning to ensure the required temperature and humidity. Satellites have strict requirements for cleanliness, and people who come into contact with them should be wrapped all over and put on masks, just like the laboratories of the institute. Ensuring the matching between on-board equipment and ground equipment and solving the problems in the test are the first level of the satellite at the launch site. After passing the test, the satellite will be refueled to meet the power demand of the satellite's orbit, attitude control and normal operation. In the eyes of ordinary people, weather forecast means high temperature and low temperature, windy and rainy, but here it is related to the success or failure of satellite launch. After the rocket and satellite pass the test in the launch area, depending on the weather and according to the orbit window of the satellite, it is decided whether to refuel or stand by and launch. The so-called launch window is the time range during which the spacecraft is allowed to launch. The launch window of spacecraft is determined according to the space mission and external constraints. The external conditions affecting the launch window mainly include the orbital conditions of celestial bodies, the orbital requirements of spacecraft and the working conditions of spacecraft, as well as the launch direction, ground tracking control and meteorological conditions. As far as space missions are concerned, there are three launch windows. One is the annual window, which refers to the number of consecutive months in a specified year, and is suitable for interstellar exploration missions. The second is the monthly table window. It is expressed by the number of consecutive days in a month, which is suitable for planetary and lunar exploration missions; The third is the calendar window. It is expressed in the form of a certain time of a day to another time, which is suitable for all kinds of spacecraft. The launch of Chang 'e-1 satellite, considering the shortest relative distance between the moon and the earth, has a better chance of rendezvous with the moon in orbit. It is only suitable for launching once a month, and each launch window is 35 minutes. If we miss the chance, the next launch will take a month. The boiling point of water is 100℃, while the boiling points of the other two liquids flowing in these pipes are -253℃ and-183℃ respectively. They are the most important propellants of rockets, called liquid hydrogen and liquid oxygen. At present, there are more than 100 kinds of liquid propellants that have been studied and put into test, which are divided into oxidant and combustion agent. Liquid oxygen, nitrogen tetroxide and nitric acid are commonly used oxidants, which mainly play a role in supporting combustion. Liquid hydrogen, kerosene and unsymmetrical dimethylhydrazine are combustion agents. Among these commonly used propellants, liquid hydrogen and liquid oxygen have the highest energy and the largest specific impulse.