If it is simple to put satellites or spacecraft and other payloads into different orbits, this general launch vehicle can do it.

But if you want to put six or seven, a dozen, or even dozens of satellites into different orbits at the same time, you need an upper stage.

To put it bluntly, it is also a first-stage rocket, but it is more flexible than the general rocket body, and it not only has flexible orbit change capabilities. Moreover, its engine can also be ignited multiple times, which can run in orbit for a long time, and has a strong space transfer capacity.

Wu Hao: The reason why they developed the upper-stage technology was to improve the carrying capacity of the rocket, especially the transportation capacity of deep space and different orbits.

Of course, this is only one reason. On the other hand, it is also their hope that they will be able to use it to develop multi-star technology.

On the basis of the original technology, Wu Hao and they have also made relevant improvements and optimizations to make its performance more excellent.

First of all, in terms of quantity, it is different from the current multi-satellite technology of many countries, which can send two or three, or four or five satellites, into the sky. Wu Hao and the others hope that with the help of this technology, they can send more than a dozen, or even dozens of satellites, into space.

Secondly, in orbit, Wu Hao hopes that this upper stage can carry more than a dozen or even dozens of satellites to different orbits.

At present, the technology of one arrow and multiple satellites has developed very rapidly, and companies in various countries have experimented or have used this technology, and have successfully sent more than a dozen or dozens of satellites into space.

For example, the Starlink project implemented by Musk has sent 60 satellites into space at a time, which can be said to be very remarkable.

However, these multi-satellite technologies can only send these satellites to the same orbit. That is, after the launch vehicle has sent several satellites to a predetermined orbit, they are released in turn.

However, there is a problem with this, that is, the orbit of the rocket release or the satellite is a curved upward trajectory. But if you look up from the top or down, the curve becomes a straight line. That is, it is still on the same track, but at different altitudes.

In this way, it seems to solve the problem of multiple satellites squeezed into the same orbit.

However, this is only temporary, except for geostationary satellites at the equator, all other satellites will gradually lose altitude due to fuel consumption during operation.

There are also differences in performance between satellites, and these satellites also have different descent times and velocities, so there is a lot of risk associated with that.

Descending satellites may affect the operational safety of satellites in Earth orbit, resulting in collisions and even a series of chain reactions.

For example, in the Starlink program, which has been relatively hot in recent years, Musk used a Falcon rocket to launch 60 satellites at a time.

But these 60 moons form a string of pearls, which means that they are all in the same orbit. So on a clear night, we will also often see a string of satellites in the sky transiting.

And Wu Hao didn't want this long string of pearls, but wanted to have the ability to send more than ten satellites to different orbits.

Truly like a space bus, sending these satellites to their intended destinations.

So this technology is still relatively difficult, and its difficulty is no less than that of a spaceship. It is necessary to achieve precise control of the upper stage, and only in this way can each satellite be sent to its own accurate orbit.

At present, in the field of satellite technology, countries and companies are no longer simply pursuing weight and volume, but are paying more and more attention to some tiny satellites.

Compared with ordinary large and medium-sized satellites, micro satellites have their unique advantages. First of all, its biggest advantage is the cost, the cost of a tiny satellite is very low, and the cost of a satellite may even be the price of a smartphone.

For example, many college student research teams have developed a lot of mobile phone satellites. In fact, the theme of mobile phone satellite is mobile phone, relying on the mature electronic components and equipment on the mobile phone to carry out certain transformation, so as to manufacture a satellite. The satellite itself is very inexpensive to manufacture, and the most expensive part of it is the launch.

If the traditional one-to-one single launch method is followed, such a mobile phone satellite has to bear the launch cost of the entire rocket, which is very expensive.

Even if several of these tiny satellites are sent into the sky using multi-satellite technology, the price is very high.

So how to reduce costs has also become a problem that scientists and technologists have been thinking about.

Second, this kind of microsatellite is convenient for manufacturing, transportation, launch, and deployment, and it is also conducive to launching and deploying a large number of microsatellites at one time, so as to resist the enemy's range-line weapons.

It is precisely because of these advantages that the development of small satellites and microsatellites is very rapid.

In recent years, with the country's opening up in the aerospace field, more and more scientific research institutions and companies are also developing their own small satellites and micro satellites.

Wu Hao: They also saw the broad development prospects of this market, so they started this project. It is hoped that with the upper stage, many satellites can be launched and transported at one time and transported to different orbits.

In this way, together with the retractable launch vehicle, the launch cost of each small satellite and micro satellite is greatly reduced.

This will not only allow these R&D teams to take over, but also drive the development of the industry. It is also a good thing for Wu Hao, this move can not only compete for this part of the order to open up the market, but also for Wu Hao in the field of aerospace technology, especially spacecraft technology, orbit change technology, and deep space exploration.

So Wu Hao was very concerned about this project, so he began to ask.

Hearing Wu Hao's greeting, Yu Chengwu nodded with a smile and said, "The project is progressing smoothly, and we initially plan to divide the entire project into a three-step strategy.

First of all, the first step is to develop and manufacture five to ten upper-stage spacecraft, which can meet the launch needs of the current two types of rockets, and can send five to ten small satellites to their predetermined orbits at one time.

The second step is between 10 and 30 satellites, which means that we can put up to 30 small satellites or microsatellites in different orbits.

This has almost reached the maximum transport load of our Jianmu 2, so this upper stage will also be the main force of our launch for a long time to come.

In the third step, we plan to increase the scale to about 30 to 100 large upper stages, so as to achieve about 100 small satellites or micro satellites into different orbits.

……”