Section 1. Touring Beijing Space City

场景介绍：北京航天城是中国航天员的摇篮，中国航天员中心和北京飞行控制中心坐落其中，凯文与航天专家现场交流，了解航天员的典型训练设备和设施……

Kevin has passed the college entrance examination this summer and is admitted to Beihang University. This summer vacation will be the most relaxing time for him in his entire life. Kevin is a fan of Yang Liwei, the first astronaut of China. He has read many stories about the Chinese astronauts and his dream is to be an astronaut in the future. To his excitement, he luckily wins an opportunity to visit Beijing Space City in a weekend. Mr. Ivan, a professor of Beijing Space City, explains the details of different facilities.

Astronaut Center of China

Ivan: Welcome to Beijing Space City! I am Ivan and I work in Astronaut Center of China, ACC.

Kevin: Thank you, Mr. Ivan! My name is Kevin. I am so excited about the visit!

Ivan: The first place we are going to visit is ACC. The full name of ACC is China Astronaut Research and Training Center. You know, this name is a little bit long, so we often use the name Astronaut Center of China instead.

Kevin: The main job of ACC is astronaut selection and training, is that right?

Ivan: Yes, astronaut selection and training is the most important work of ACC. You will see some of the training facilities during the visit. Nevertheless, ACC also has many other responsibilities.

Kevin: Can you explain?

Ivan: Ok. In addition to the astronaut selection and training, ACC also studies and manufactures many space products such as the space suits, the space food, the environment control and life support system, the space medical monitoring devices etc. Basic researches in space medicine and human factors engineering are also conducted in ACC.

Kevin: Can you say something about those basic researches?

Ivan: ACC has two national key laboratories. One is called the State Key Laboratory of Space Medicine Fundamentals and Application, which mainly studies the adverse effects of space environment on the human body and how to mitigate those side effects. The other is called the National Key Laboratory of Human Factors Engineering, which studies how the human and machine better match each other to improve the performance of a system. These studies can help ensuring the safety, health and good performance of astronauts.

Kevin: That sounds difficult!

Ivan: Maybe. Next, I will show you something not so difficult. Let's go to the astronaut training hall.

Kevin: Great!

Ivan: This is the mock-up of Tiangong-2. The inside and the size of this mock-up are exactly the same with Tiangong-2 flown in space. The facility beside Tiangong-2 mock-up is called Fix-based Spaceship Training Simulator.

Kevin: Can I see the inside of the simulator?

Ivan: Yes, you can. Just like the aviation simulator, this simulator is used by astronauts to learn spaceship operations. The upper part is the orbit module of the Shenzhou spaceship and the lower part is the return capsule. During training, the crew, wearing pressure suit, practice all kinds of operations of the spaceship. They often have to stay inside the simulator for several hours just to finish one training sortie.

Kevin: How does the astronaut go to the bathroom during training?

Ivan: They will not go to the bathroom. Instead, they use diapers, just like the real flight.

Kevin: Can this simulator simulate the micro-gravity environment?

Ivan: No, it cannot. It just simulates all kinds of flight procedures. The astronaut can be trained here to master the normal procedure, the abnormal procedure and the emergency procedure.

Kevin: What is the smaller facility on the right?

Ivan: That is also a spaceship simulator, but it is dedicated for rendezvous and docking training or RVD training. RVD means the meeting and connecting of two space vehicles. With RVD technology, we can transport crew and resupply cargos into space.

Kevin: Amazing!

Ivan: Let's visit another training site, the human centrifuge.

Kevin: I have seen it in a TV program, it rotates and creates higher gravity, right?

Ivan: Yes. Astronauts trains their hyper-gravity tolerance here on this human centrifuge. The centrifuge will create up to 8G during the training, that means the stress is eight times the weight of the body. It is very challenging! But if you want to be an astronaut, you must pass this test.

Kevin: It seems very hard, but I am not afraid!

Ivan: Let's visit the next site, the NBL.

Kevin: What is NBL?

Ivan: NBL is the abbreviation of Neutral Buoyancy Laboratory. It is also called the weightlessness simulation water tank. In colloquial language, it is often called the “pool”.

Kevin: I can see some modules inside the pool.

Ivan: Yes, they are the mockups of the spacecraft and segments of the China space station.

Kevin: What is the purpose of this pool?

Ivan: It is mainly used for EVA training, or space walk training. EVA means extravehicular activity. Of course, it also serves as a research facility to do some experiments, for instance, verification of EVA procedures, or human factors researches.

Kevin: How are the astronauts trained here?

Ivan: I will show you a video, and you are able to see the complete EVA training process.

Kevin: That's amazing! Why do astronauts take this training?

Ivan: You know, astronauts in space will experience weightlessness or micro-gravity, so they must learn how to work in micro-gravity.

Kevin: How long does this training take?

Ivan: It takes several hours for the astronauts to complete one training session. But the scuba divers who support the training underwater will change shifts every two hours. It is quite demanding physically for the astronaut, because he or she must always fight the residual pressure in the training suit.

Kevin: Are the training suits the same with EVA space suit in space?

Ivan: No, it is not the same. You see there is an umbilical cord connected to the underwater training suit which provides the oxygen and ventilation. In space, the real EVA space suit has a life support system in the backpack providing oxygen and removing the carbon dioxide exhaled.

Kevin: Thank you for the explanation!

Ivan: You are welcome! And that's all for the visit of ACC. Next, we will visit BACC, Beijing Aerospace Control Center.

Beijing Aerospace Control Center （BACC）

Kevin: I have seen this building many times on TV.

Ivan: Yes, almost all the space missions in China are controlled in this building. Let's go inside. First, let's see a short video about BACC. Then, we will go inside to visit the control hall.

Kevin: That's great!

Ivan: That's all for the video. You know, BACC was founded in 1996. But it has witnessed many milestone space missions of China, including the first unmanned spaceship mission, the first manned missions, the Tiangong mission, the Chang'e lunar exploration missions, etc. Soon we will see the construction of the China Space Station, and even the mission to Mars.

Kevin: So, when the astronauts are flying in space, all the communications and operations are controlled here?

Ivan: Yes. For any space flight mission, we must have a Tracking, Telemetry & Command and Communication System or TT&C and C system. It is just like flying a kite, we need a tread to control it.

Kevin: Is “Yuanwang” tracking ship part of the system?

Ivan: Yes. To ensure the communication coverage rate, we have not only the “Yuanwang” tracking ship, but also many fixed stations on the ground around the globe and the “Tianlian” relay satellites in space.

Kevin: What does the communication coverage rate mean?

Ivan: It means, when circling around the earth, the percentage of communication time you can have with the ground. Of course, 100 percent means the communication is established with the ground at any time.

Kevin: I understand. Thank you!

Ivan: Let's go inside to the control hall.

Kevin: Ok!

Ivan: The control hall is a two-story tall building. The large display in the front can show photos, videos, animations, and various parameters of the spacecraft. The first floor is the working place, you can see rows of consoles. The second floor is for visitors. Guests can watch space operations on the second floor.

Kevin: Marvelous! Are the state leaders talk to the astronauts in this room?

Ivan: Yes, this is the phone they used to make the space call. That's all for the visit of BACC. You can take a photo here.

Kevin: Thank you!