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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
This kind of jobs in security field however does not include working on offenses such as motor vehicle traffic violations and accidents. It is the job of a security guard to merely protect the individual or prevent any damage or destruction of the assigned property. Peace officers are widely used to protect all property and people as well as enforce laws.
Even the cost of motorcycles and cars differ also. Most of the time, cars are more expensive than motorcycles. Because a car is bigger, it is usually expensive for maintain. Cars have more accessories when compared to a motorcycle besides having four wheels. However, there are several motorcycles which is higher priced than the usual car.
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