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Spacecraft flew hundreds of thousands to hundreds of millions of kilometers from the earth, injecting speed when the size and direction of a slight error, arrived at target planets will appear large deviation error, for example, when Mars probe injecting speed 1 m/s speed (about one over ten thousand), arrived at Mars, about 100000 km distance deviation. Therefore, precise control and navigation must be carried out during the long flight. Flying to the moon is usually controlled by the orbital control system of the ground and space probe (see orbit control). Interplanetary flight distances, radio signal transmission time is long, the real-time remote control, can't so planets and interplanetary spacecraft orbit control system shall have the ability of autonomous navigation (see interstellar travel navigation and control). The United States, for example, "pirates" spacecraft in space flight of more than eight hundred million km, for 11 months of 2000 times of autonomous orbit adjustment, the final surface to achieve a soft landing on Mars, placement accuracy up to 50 km. In addition, in order to ensure the accuracy of the orbit control engine, the communication antenna is always aimed at the earth, and other systems work normally, and the detector has the autonomous attitude control ability
Based on the complexity of today's technology, the pure practice of technology will require a great understanding, which is the result of many years of experimentation, success, failure, and general experience. Therefore, a great deal of knowledge needs to be stored and passed on to the next generation by experts. Its training and education are conducted in formal and informal education institutions, schools, colleges and universities. Imagine the vast knowledge needed to enter careers such as medicine, engineering and architecture
When the dog chewed the leash the lead went within the case and unraveled the coil spring. With the case facing you possess it steady and grab the loose end from the lead and pull for the cause add tension. Now that you have about two feet of lead out, support the mechanism while preventing the lead wheel assembly from unwinding rewind the additional lead that you just pulled out, without releasing the stress.
The automatic filter consists of shell, multiple filter element, anti-flush mechanism, electric control box, reducer, electric valve and differential pressure controller. Casing of diaphragm plate inside cavity can be divided into upper and lower two cavity, the cavity is equipped with multiple filter core, so that make full use of the filter space, significantly reduce the filter size, are installed in the inferior vena backwash suction cups.
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