How wonderful is chang’e-5’s return to space?

The 23 day chang’e-5 sampling mission has come to an end. The final chapter is also the most worthy drama. The collected samples re-enter and return to earth. This is another sample of the moon after 44 years. It’s not easy to return. < / P > < p > in terms of speed, the spacecraft will run out of the earth in three steps: the first jump, breaking through the first cosmic speed of 7.9 km / s, can move around the earth; the second jump, breaking through the second cosmic speed of 11.2 km / s, can leave the earth forever; the third jump, breaking through the third cosmic speed of 16.7 km / s, can leave the solar system forever. According to the kinetic energy equation, the energy is directly proportional to the mass of the spacecraft and the square of the required velocity, and also takes into account the air resistance, the mass and velocity of the rocket transporting it. When chang’e-5 goes to the moon, it must escape the earth’s gravity and be captured by the moon. Considering the requirements of orbit change and margin, it must reach the second cosmic speed. The cost is huge: chang’e-5 weighs only 8.2 tons, and it will consume an 870 ton long March-5 rocket. < / P > < p > when it comes back, the spacecraft’s own braking ability is weak in front of the earth’s gravity, and the earth’s strong gravity will make the returning chang’e-5 orbiter / re-entry device reach the speed of the second universe again. This is troublesome, because the air resistance is similar to the kinetic energy equation, and is also proportional to the square of the speed. Such a fast speed will produce a far greater impact than the Shenzhou spacecraft. On the one hand, friction produces a lot of heat; on the other hand, the huge and continuously accumulated impact load may lead to structural problems and the material can’t stand it. For example, the speed limit of 110 yards on high speed is only about 30 m / s, and that of chang’e-5 is 11000 + m / s. How dare you open the window at such a high speed? If you dare, I’ll give you another 300 plus. Can you stand it? < / P > < p > the answer is, I can’t stand it, so I have to find a way. The effective solution is to float in the water. The reason seems simple: when the stone floats on the water, it instantly contacts the surface of the water to produce enough “buoyancy” to make it break away from the surface of the water, “slow down” and then fall back and forth several times, and finally fall to the bottom of the water. < / P > < p > of course, chang’e-5 is more complicated than that. Because the air density varies from place to place, the angle and attitude of rushing into the atmosphere are extremely difficult to control, every time you rush into the atmosphere, you must ensure that you do not exceed the endurance limit of the return capsule, the number and interval of “floating” must be accurately calculated, and you must accurately fall back to Siziwang Banner in Inner Mongolia. It’s a remarkable thing to pass it on. < / P > < p > chang’e-5 will probably rush into the earth’s atmosphere from the Arabian Sea near Africa, make two big “water floats” and become “man-made meteor”, jump up over Tibet, and finally return to the hands of astronauts through aerodynamic, parachute deceleration and ground search. < / P > < p > chang’e-5 is the most complex mission in the history of China’s space flight. Every step is “startling”, but in fact, it has also completed “step by step”. Obviously, there are countless smart people working around the clock to support it. They are worth praising! Continue ReadingDeveloped a “plug and play” solar power generation scheme, and “5B” won a $12 million round a financing