The rise of nanometers

Tiangong Space Station.

Nie Changfeng and He Zhen, who are stationed at the station, have a clear division of labor.

As the captain, Nie Changfeng is mainly responsible for general control, communications, and cooperation with scientific research; while team member He Zhen is responsible for space operations and equipment maintenance.

When the Shenzhou spacecraft successfully returned to the ground, the Tiangong Space Station officially entered working status.

The current Tiangong Space Station, after six launch missions, has a total weight of 295 tons, which is about three-quarters of the International Space Station. The internal space volume is 732 cubic meters, which is equivalent to seven-ninths of the International Space Station. about.

It has 18 independent space capsules and 3 new space capsules that are about to be assembled. The space and supplies above can allow 2 to 4 people to survive in the space station for a long time.

If the three new space stations are assembled, the internal volume of the Tiangong Space Station will be increased to 844 cubic meters.

Node 5 is where the new space capsule is assembled.

After putting on the space version of the exoskeleton armor, He Zhen opened the air-tight door and began to perform extravehicular operations. First, he fastened two fixed ropes, one end to his body and the other to the fixed handle in the cabin.

The assembled space capsule is somewhat different from the ground-assembled space capsule. He first installed the four main frame columns at the connection parts of the node cabin.

The next step is to assemble the sub-skeleton modules one by one according to the numbers, just like installing a jigsaw puzzle.

After the skeleton is installed, the next step is the external composite protective layer, which is mainly used to defend against space debris impacts, high-energy particles, solar storms, and radiation heat dissipation layers. These are all combined on the outer composite layer.

The inner composite layer is mainly used for air sealing, thermal insulation, radiation protection and fire protection.

The last thing is the pipeline system and electrical system inside.

He Zhen spent a week assembling the three space capsules, and tested the air tightness and a series of other functions. Although he encountered some minor problems, he overcame them one by one.

The three new space capsules, in addition to one node capsule, the other two space capsules, one is a data capsule, equipped with three large servers; the other is a communication experiment module, used for communication experiments.

After the three space capsules were put into use, Nie Changfeng came to the communication experimental cabin, controlled the equipment inside, and fired a positioning laser to the ground.

[Tiangong, Tiangong, this is Qinghai, the laser positioning is accurate. ]

Nie Changfeng picked up the communicator and sent back a message: [Tiangong received it, and will conduct the first experiment in 5 minutes. ]

[Received in Qinghai. ]

Nie Changfeng opened the control panel of the laser transmitter. After editing the information, he started to activate the communication laser and fired a communication laser towards Qinghai Station.

Soon the Qinghai Station received the communication laser signal.

In the communication experimental cabin, communication lasers are continuously emitted to the ground, while the Qinghai Station, Changbaishan Station, and Wuyishan Station on the ground are also emitting communication lasers to the space station.

Nie Changfeng activated the camera in the experimental cabin and tried to synchronize his own images to the ground.

After a while, the other party's screen appeared on the monitors of both parties. Although there was a delay of about 0.05 seconds, the download and upload of communication information reached 9.6GB and 9.2GB per second respectively. This is a quite large communication. density.

Of course, laser communication has many limitations. For example, it requires special equipment, is easily affected by weather, and must be aimed to communicate.

As between outer space and the ground, and between space, it is only so-so.

If you want to apply it to the civilian market, such as Musk's Starlink plan, it can only be used on sea ships, uninhabited areas, and areas without communication facilities.

Because communication in space faces a huge problem, that is the total amount of communication.

The so-called 9.2~9.6G speed per second is actually the speed of a laser to a communication device. What if 10 people are using it at the same time? Or what if hundreds of people are using it at the same time?

As the number of users increases, the personal communication speed will be divided into smaller pieces while the total amount of communication remains unchanged.

10 people, the remaining speed is about 900M per second.

If there are 100 people, about 90M per second will be left.

1,000 people…

By analogy, the more users there are, the less communication speed an individual is allocated. Moreover, laser communication must be positioned and directional, and users cannot be concentrated in a small area, so the communication quality can be imagined.

Starlink plans to launch 42,000 satellites, with a total communication capacity (i.e. bandwidth) of approximately 400,000 GB per second. If individual users are to maintain a communication speed of 5MB per second, the user limit is 80 million.

If the communication speed of 100M per second for individual users is to be maintained, the Starlink communication system can only allow up to four million users to access the Internet at the same time.

What's more, arranging 42,000 satellite communications in low-Earth orbit would be simply disastrous, because the service life of these satellites is limited and satellites must be replenished frequently. The abandoned satellites will become dense space junk, which will increase human exploration. The difficulty of outer space.

The Starlink project is not like a communication system, but more like a weapons system.

The purpose of the current experimental laser communications at the Tiangong Space Station is to study high-quality laser communications, as well as outer space communications for satellites and spacecrafts.

Nie Changfeng communicated with the three laser communication stations on the ground for more than 20 minutes. Due to the orbital detour, the communication was interrupted.

For laser communication systems in outer space, if you want to preserve uninterrupted communication, you can only use multi-point arrangements to achieve this.

The laser communication laboratory on the Tiangong Space Station has no other auxiliary communication satellites and can only conduct communication experiments with the ground during the window period.

After completing this laser communication experiment, Nie Changfeng did not leave, but turned around and entered the second half of the laser communication laboratory cabin.

A high-energy laser transmitter was installed here. He adjusted the direction and locked on a piece of space junk 324 kilometers away through Beidou satellite and Gaofen satellite.

It was a discarded solar panel about 4 meters long and 0.8 meters wide.

Carefully controlling the laser, and with the assistance of the positioning system and high-definition satellites, Nie Changfeng pressed the laser launch button.

A high-energy laser that is invisible to the naked eye bursts out from the laser. The laser emits laser light, and the reaction force generated even pushes the Tiangong Space Station slightly, causing the space station to shift by a few centimeters.

The laser instantly irradiated the abandoned solar panel. Under the irradiation of the laser, the temperature of the solar panel rose rapidly and it also fell toward the atmosphere.

[alarm! The target has shifted! ]

Nie Changfeng immediately turned off the laser and observed the movement of the abandoned solar panel.

The solar panel, which was originally floating near 307 kilometers of low-Earth orbit, began to fall rapidly downwards after being hit by a laser.

After observing for a while, Nie Changfeng started the laser again, giving the solar panel a new acceleration.

After seven consecutive irradiations, the orbital altitude of this piece of space junk has dropped to around 157 kilometers.

At this point, there is no need to irradiate it anymore, because the planet's gravity will quickly pull it down from the atmosphere, and then it will be burned in the atmosphere.

NASA's space junk monitoring system also discovered anomalies in this piece of space junk. Whether it was the sudden rise in temperature or the weird acceleration, it showed that someone was controlling this piece of space junk.

Although they were unable to pinpoint which spacecraft launched the laser, there were only four forces in outer space capable of doing such a thing at this time.

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