Analysis of the 3 problems of "pathfinder"

Legal Evening News (reporter Li Wenji) Chang ' E fifth tester is the third step of our lunar exploration Plan "return" Pathfinder (300005,, which is the first challenge for Chinese aircraft to return to Earth from a lunar orbit about 380,000 kilometres from the ground, which will provide experimental data for the Chang ' e fifth flight, launched in 2017. The flight tester is developed by the Space Technology Research Institute of China Aerospace Technology Corporation, which consists of two parts, service module and return device. According to the plan, the "Pathfinder" will return in 8 days, this is not a long flight test trip is due to a number of "first" and breathtaking. For example, the hem five-test-drive, the Long March third, the two-type rocket is the first flight, described as "skipping" of the "jump back" of the return of the same way is the same time. Since returning from the Moon is a road that Chinese spacecraft has never traversed, the task is new, difficult and risky, and it needs to conquer the key technologies such as aerodynamic, aerodynamic, heat, half ballistic navigation guidance and control systems. After more than 3 years of research, researchers have realized many innovations. Sudio: 7.9 km/sec Sudio: 11.2 km/sec Experts explain why the use of "jump-back" jump-type reentry refers to the spacecraft into the atmosphere, rely on lift again out of the atmosphere, using the atmosphere of the ship's lift to the spacecraft "entrusted" to the atmosphere, lower the speed and then enter the atmosphere "For example, a half ballistic jump reentry" is a bit like the stone we used in the river. "Shan Shifan, deputy designer of China Lunar Exploration project phase three, said. In addition, according to the Chinese Lunar Exploration Project Deputy Commander Liu Jizhong introduced, "reentry is to enter the atmosphere at high speed." How high is the speed? At present it is according to the speed of more than 10 kilometers per second. After re-entry into the atmosphere, it is subject to a variety of environmental constraints, including force, heat, and so on. We validated this test to get the relevant data to reduce the risk of our automatic sample return task. "If another way of return, that is," ballistic reentry ", return cabin of the reentry angle too large, will lead to high overload and high heat flow. This not only puts forward higher requirements for the structural strength and heat-resistant layer of the return cabin, but also exceeds the human overload tolerance. Even unmanned detectors, due to the limitations of the rocket carrying capacity, the return cabin can not be increased with the increase in the reentry speed blindly increase and weight. The use of "jump-back" will not only reduce overload, prevent high heat flow, but also change the trajectory of reentry, successfully extended the reentry path. After entering the atmosphere, the spacecraft relies on lift to flush out the atmosphere, reducing speed and then entering the atmosphere. This approach is most appropriate for spacecraft entering the atmosphere near Sudio. In addition, if the main landing site encountered a sudden change in weather, need to temporarily adjust the landing site, you can adjust the reentry path through this reentry, so that the return cabin to the standby landing site. When the Apollo 11th manned moon landing returned, Apollo 11th made a "quasi-jump" with the weather on the scheduled landing site, which extended the area forward by 2,700-kilometer. Changes to the landing site have made it possible for the return cabin to take a further route.To land, "jump-back" just can extend the reentry path, so that the return capsule to the ideal location. Chang ' e third commander, Director of General adviser Yeppecian said, "Through this method, the longer the distance, we can get a lot of benefits, can reduce heat, reduce landing angle and so on, this return is the first Test." "High-speed long-range flight rockets above the flight tester directly into the perigee 200 km, apogee 380,000 km of the Earth-moon transfer orbit." The aircraft returns, first enters the atmosphere, leaps first, then after a period of flight, and then the second time into the atmosphere, back to Earth. The return cabin is separated from the main control device in the orbit 5000 kilometers from the earth. When the return cabin is 60 kilometers from the ground, it will bounce back into space by adjusting the angle of attack, then the second reentry (called Jump reentry). The umbrella is an important part of the recovery system, which is directly related to whether the parachute can be straightened properly. Compared to southwest mountainous areas, the choice of landing in the northern Grassland area, open vision, conducive to recycling. This edition/reporter Li Wenji