Just when everyone was staring at the big screen, the screen of the surveillance camera of the secondary rocket body in the window suddenly stopped.

At this time, Yu Chengwu explained in a timely manner: "The rocket has entered the black barrier area, and the communication is temporarily interrupted. Next, the rocket itself will be controlled."

While Yu Chengwu was talking, the window on the big screen had switched to the observation screen of the ground optical infrared telemetry equipment. This is due to the friction between the rocket's high-speed descent and the dense atmosphere, so that the thermal insulation material of the second-stage rocket body is heated and volatilized, which is just captured by the infrared thermal imaging device and displayed on the screen.

In the eyes of ordinary people, this is a bright spot with a small tail, nothing special. But in the eyes of professionals, this highlight contains a lot of information. They can judge the descent gliding state of the rocket based on the change of this bright spot.

In the process of the normal whereabouts of the secondary rocket, the bright spot is flying with a dandy tail. If there is a problem, such as the rocket insulation material laughing, causing the arrow body to rub and burn, then the bright spot will be brighter, and the tail dragging behind it will be brighter and longer.

If this bright spot suddenly runs out of a bright spot and flashes past, it means that an object on the rocket body may have fallen off during the rapid descent and friction with the atmosphere.

If this bright spot flashes, it means that the flight attitude of the entire rocket is out of control. The rocket is not sliding down smoothly, but in a rolling state. Only in this state will the bright spot flicker.

If this bright spot suddenly explodes and separates out several bright spots with long tails, it means that the arrow body of the rocket may not be able to withstand the stress intensity generated by the descent and air friction, so that the entire arrow body directly steps in the air.

Any of the above phenomena will lead to the failure of the entire second-stage rocket return and landing experiment, which is why this technology is so difficult, and no one has achieved it yet.

And this is not just a purely technical issue, but a technical and economical issue.

Spacecraft that simply re-enter the atmosphere from space, or returnable spacecraft, and the technology of returnable satellites have been mastered by many countries and companies. It has only one purpose, to return the spacecraft or satellite safely from space to Earth.

The cost can not be considered too much, the material is naturally strong and the best, and there is no too sensitive requirement for weight.

The technical difficulty of the second-stage rocket is how to combine technology and economic benefits to find the best balance.

As we all know, in order to be able to transport heavier loads, the weight of the launch vehicle is very light, and the entire rocket body structure is very light. The purpose is to save its own weight, so that it can transport heavier and more movements.

Ninety percent of the weight of a launch vehicle is fuel, and only ten percent is the weight of the launch vehicle itself. As for the reusable launch vehicle, because it needs to be reused many times, the structure of the rocket body, including the structure of the engine, has been strengthened, which also makes its own weight increase, so that its carrying capacity may not be as good as The size of a disposable rocket.

However, relying on the advantages of reusability, this rocket can greatly reduce the carrying cost.

Of the cost of a commercial launch vehicle, only 2 to 5 percent is the fuel cost, and 95 percent is the price of the rocket itself. That is, a 100 million rocket, the price of fuel is only 5 million, and the cost price of the rocket itself needs 95 million.

The reusable rocket, although the manufacturing cost is higher than the disposable rocket, can be reused, so that the cost of the rocket itself can be saved, and all that is generated is the cost of fuel and the cost of recovery and maintenance.

If you want such a multiplexed rocket, you can win orders at a much lower price than the industry's commercial launch price. You can recover the cost after two launches, and basically make money after that. And a rocket like this, or a first-stage rocket at least, can be used six or seven times, or even a dozen times at most.

In this way, it is enough to see how profitable such a reused rocket is. Of course, commercial insurance is usually purchased during commercial launches to prevent the worst results. After all, no one can guarantee that every launch will be foolproof.

As for the insurance company, it will also evaluate and quote according to the state of your rocket. Maybe the more times the rocket is used, the higher the insurance policy quote will be, so this will also be included in the cost.

Compared with the core-level rocket, the core-level rocket is more sensitive to the weight of the arrow body, and a little more weight will reduce part of the carrying capacity. Therefore, the project technology research and development team must save the self-weight of the secondary rocket as much as possible.

But there is a premise, that is, it must ensure that the strength of the secondary rocket must meet the standard, especially in the take-off stage, it has to withstand huge gravitational acceleration, and it has to withstand huge air resistance and friction in the landing stage.

In the current world, the strength and weight of any material are proportional. That is to say, the heavier the weight of the material itself, the higher the strength, and the smaller the weight of the material, the lower the strength, which cannot be changed by anyone.

So this is a contradiction, and a major goal of the technical research and development team is to find a balance between the two~lightnovelpub.net~ that is to use the lightest material to achieve the maximum strength of the arrow body.

Although there will be a certain redundancy between the design parameters and the actual environment, that is to say, the strength of the rocket itself is higher than the stress it will be subjected to in reality to ensure that the rocket body can withstand a harsher environment than reality.

But in real operation, there are too many uncertain factors, maybe a little change will lead to the failure of the whole task, which is very common in reality.

To give a simple example, there is currently a large amount of tiny particles of garbage in the low orbit of the earth. Many of these are natural celestial bodies, meteorites, etc., some are artificial garbage, and some debris from spacecraft.

These debris are burned up in the high-speed orbit of the earth's orbit and the falling atmosphere, and the rocket needs to pass through the low-altitude orbit and the atmosphere, which also means that it may collide with these orbiting and falling debris.

Unlike general spacecraft, which have an anti-collision design in this regard, the launch vehicle has no anti-collision layer in order to ensure the absolute lightness of its own weight. Maybe a fragment will break down the body of the integrated rocket.

The so-called "a thousand miles" is destroyed in the ant's nest, and it is possible that the damage and trauma at this point can make the entire rocket disintegrate in the rapid descent.