Interstellar spacecraft migration

At present, the world's largest space rocket-spacecraft system has been assembled. A 70-meter booster and a 50-meter spacecraft form a space launcher with a total height of 120 meters, which is 10 meters higher than Saturn V 50 years ago. There are precedents for such a huge project, but Musk's design is wonderful here-although huge, it is not expensive. This completely subverts the general understanding of the aerospace field and ordinary people: the bigger the rocket-spacecraft, the more complicated the system.

Musk's series of designs revolve around one core-cost economy.

Manned space flight and even landing on the moon must be supported by a huge and complex system of heaven and earth, which is originally an extremely expensive field. In order to ensure absolute safety, the past space program never dared to make a fuss about saving money. For almost everyone, it is a matter of course that the manned space program must be expensive.

So we can see the excellent quality of Musk, a person who doesn't take the usual path. Of course, all people who engage in aerospace also understand that the commercialization of aerospace must take the road of greatly reducing costs. Commercial satellite launches have always been this way, but in the past, it was not obvious that it was carried out by official institutions. After Musk engaged in the Falcon rocket, he actually reduced the launch cost (of course, it is not obvious at present).

In the past, no one dared to think about the idea of reducing the cost of manned space flight under the existing conditions, unless there was significant progress in launch technology, such as the idea of "space plane" that was successfully tested by stages in China a while ago. The route of the "space plane" was studied by the United States and the Soviet Union decades ago. The requirements of engineering technology are too high, and it is too difficult to break through technical barriers. Now only China has robbed the baton.

Musk believes that ordinary people dare not think about it, and designed his "Starship Plan", which must greatly reduce the cost of manned space flight within the scope of existing technical means. Therefore, the gimmick of "Millions of Immigrants Colonizing Mars" is not important at all. Musk didn't believe the cow he blew. The real meaning of his words is that there will be such a thing as large-scale colonization of Mars only if the cost is greatly reduced to the extent that ordinary people can afford the ticket. Therefore, the core element of the "Starship Plan" is to "let ordinary people buy tickets and take off into space".

Why is Musk's idea evil?

Because in the past, it was thought that in order to reduce the cost, it was necessary to reduce the structural weight of the rocket itself and increase the specific impulse as much as possible to increase the payload. Therefore, the arrow body should be made of light carbon fiber, the arrow body should be as light as possible, the fuel should be liquid hydrogen and liquid oxygen, the number of engines should be as small as possible, the thrust of a single engine should be as large as possible, the design redundancy should be reduced as much as possible, and the dead weight should be reduced.

In fact, the effect of this technology on reducing costs is very limited. Light solid materials, high specific impulse fuel and large thrust engines are not cheap, and the design and manufacture are also quite difficult. In the past, all countries took this road to improve the level of space technology-developing new materials technology, developing large thrust engines, and studying the low-temperature storage and use technology of liquid hydrogen and liquid oxygen.

Musk did just the opposite. He is not a scientist, but a businessman with a scientific dream. So he thinks about aerospace engineering from the perspective of a businessman. Businessmen don't pursue absolute Excellence, but pay attention to reasonable advancement under commercial conditions, that is, put cost control before technological advancement, and then carry out technology research and development around cost control.

Therefore, the engine does not pursue large thrust, the rocket material does not pursue thinness, the rocket fuel does not pursue high specific impulse, and the spacecraft design does not pursue the ultimate load ratio, but reduces the cost from the perspective of reusability and simplified production. This idea of breaking through the thinking mode of technical experts is very valuable!

The whole concept of starship is interlocking.

1, stainless steel arrow body is very cheap, although heavy, but the material is extremely cheap, easy to process, easy to build, easy to mass production, and very suitable for repeated use, and the maintenance after use is also very simple and easy.

2. The specific impulse and thrust of the liquid oxygen methane engine are not high, but it is easy to be reused, the fuel cost is low, the engine design and manufacture are simple, and it can be produced on a large scale. It is not a problem to make hundreds or thousands of assembly lines a year.

3. The rocket uses a large number of engines in parallel. Although the dead weight is heavy, the design redundancy is high and the load ratio is low, it is very suitable for reuse design, and the cost can be reduced through repeated use, and it is easy to make up for the short board with low load ratio on a large scale.

4. Although there is a problem of reducing the safety margin when multiple engines are connected in parallel, it can be compensated by increasing the thrust margin. The engine with smaller thrust is easier to manufacture, so the safety design can be improved as much as possible in the manufacturing process. The parallel design of small thrust and multiple engines has obvious advantages in rocket reuse, and it is easier to control thrust and save fuel in the rocket descending recovery section.

5. The problem of low load ratio can also be solved by multiple launches, which subverts the previous idea of minimizing the number of launches in space mission design. When the starship died, it refueled in space through the second launch. Anyway, the launch cost is low, which can completely offset the cost increase caused by multiple launches.

Of course, it is hard to say to what extent this idea can become a reality. The starship program has just begun, and it is not known whether it can be successfully put into orbit this year. Before, the upper test of starship experienced many failures, and the number of successes was very few. The booster test has not been carried out once, and it is still far from success and maturity. The starship booster uses 29 engines in parallel, which is as complicated as the Soviet N 1. I'm afraid the safety test will not go well.

Fortunately, the test frequency and speed of space exploration technology company are very high, which shows that the test cost control has obvious advantages, which is not available in previous space experiments. Musk's approach is indeed subversive.

At present, China Aerospace is also learning from Musk's ideas-no longer taking high technology as the only development path, pursuing economic application in the field of commercialization, and making up for the defects of system units with overall advantages. However, this does not mean that China's space flight has completely turned to the Musk route. In the non-commercial fields of aerospace, especially in frontier fields such as deep space exploration, the pursuit of high precision cannot be relaxed at all. This is also the reason why the research and development of the 500-ton high-pressure afterburning liquid oxygen kerosene engine and the 200-ton hydrogen-oxygen engine of the Long March 9 system continue to accelerate.

What's more, the United States is also engaged in inheriting Saturn 5' s large thrust engine and heavy launch vehicle in the high-end aerospace field.

In the long run, Musk's rapid prototyping idea has a fatal problem-the carrying efficiency is too low. To truly solve the pain point of low space payload, it is still necessary to make a breakthrough in advanced technology, so the technical route of two-stage orbital combined engine is the right way for future space development. I am glad that Chinese astronauts are at the forefront of the world in this respect.