The core module of the space station is about to launch. Why is it responsible for the launch of the space station?

产品：中国科普

Product: Popular Science in China

制作：太空飞船

Production: space craft

中国科学院计算机网络信息中心监制

Supervised by computer network information center of Chinese Academy of Sciences

据中国载人航天工程办公室消息，2021年4月23日，中国空间站"天河"核心舱和长征5B姚二号运载火箭总成已转移至发射区，发射前功能检查、联合试验等工作已按计划进行。

According to the China Manned Space Engineering Office, on April 23, 2021, the core module of China Space Station "Tianhe" and the long march 5B yao-2 carrier rocket assembly have been transferred to the launch area, and the pre launch functional inspection, joint test and other work have been carried out as planned.

长征五号的低地球轨道容量为25吨，同步转移轨道容量为14吨，地月转移轨道容量为8吨。它可以执行多种航天发射任务，将成为中国空间站建设的核心载体。然而，长征五号火箭的发展对世界和中国都是一个巨大的挑战。

The long March-5 has a low earth orbit capacity of 25 tons, a synchronous transfer orbit capacity of 14 tons, and an earth moon transfer orbit of 8 tons. It can carry out a variety of space launch missions, and will be the core carrier in the construction of China's space station. However, the development of long March-5 rockets is a great challenge in the world, as well as for China.

建造长征五号火箭有多难？只要我们比较一下长征五号火箭和传统的长征家庭火箭的区别，我们就能知道答案，理解为什么它能承担起发射中国空间站的任务。

How difficult is it to build Long March 5 rocket? As long as we compare the difference between the Long March 5 rocket and the traditional Long March family rocket, we can know the answer and understand why it can take on the mission of launching the Chinese space station.

新型火箭推进剂

New rocket propellant

传统的长征系列火箭，包括长征二号、三号和四号火箭，均采用氧化亚氮/偏二甲肼推进剂组合。它们毒性大，发射准备期长，价格昂贵，比冲低。比冲量是衡量单位质量推进剂冲量的指标。一般来说，数据越大，火箭推进能力越强。相比之下，液氧煤油和液氧液氢推进剂更好，也是世界主流大型火箭的选择。

Traditional Long March family rockets, including long march No.2, No.3 and No.4 rockets, all use nitrous oxide / unsymmetrical dimethylhydrazine propellant combination. They are highly toxic, have long launch preparation period, are expensive and have low specific impulse. Specific impulse is an index to measure the impulse per unit mass of propellant. Generally speaking, the larger the data is, the stronger the rocket propulsion capability is. In comparison, liquid oxygen kerosene and liquid oxygen liquid hydrogen propellants are better, and they are also the choice of mainstream large rockets in the world.

因此，长征五号的一大变化是其核心推进剂是液氧煤油（助推器）和液氧液氢（一次和二次核心）的组合。由于液氧和液氢的稳定储存温度极低，它们是-183℃ 和-253℃, 长征五号也分别被命名为"冰箭"。

Therefore, a major change of Long March 5 is that its core propellant is a combination of liquid oxygen kerosene (booster) and liquid oxygen liquid hydrogen (primary and secondary core). Because the stable storage temperature of liquid oxygen and liquid hydrogen is extremely low, they are - 183 ℃ and - 253 ℃, respectively, the Long March 5 is also named "ice arrow".

新型火箭发动机

New rocket engine

如果推进剂被更新，这意味着发动机也将被更新。火箭发动机具有推力大、爆发力强、耐热、耐寒（从极低温度到几千摄氏度的燃烧温度）、结构坚固、控制精细、稳定性强、重量轻等优点，这不容易吗？

If the propellant is renewed, it means that the engine will also be renewed. It is not easy for a rocket engine to have the advantages of high thrust, strong explosive force, heat resistance and cold resistance (from extremely low temperature to combustion temperature of several thousand degrees Celsius), strong structure, fine control, strong stability and light weight?

这也是发动机被称为"火箭心脏"的原因。它的研发难度直接导致它成为世界上为数不多的能够制造大型火箭的国家之一。

This is also the reason why the engine is called "rocket heart". The difficulty of its research and development directly leads to one of the few countries in the world that can make large rockets.

展览中的Yf-100k发动机（开源图片）

Yf-100k engine in the exhibition (open source pictures)

长征五号需要同时研制yf-77（液氧液氢推进剂，用于堆芯级）、yf-100（液氧煤油推进剂，用于助推器）和yf-75d（液氧液氢推进剂，用于两级）三台发动机，难度可想而知。

For the Long March 5, it is necessary to develop yf-77 (liquid oxygen liquid hydrogen propellant, used for core stage), yf-100 (liquid oxygen kerosene propellant, used for booster) and yf-75d (liquid oxygen liquid hydrogen propellant, used for two-stage) three engines at the same time, so the difficulty can be imagined.

新型火箭上级

New upper stage of rocket

长征五号是一系列多用途火箭。在执行高轨道和深空探测任务时，它还需要搭载第三级，即上一级，这类似于太空渡轮的效果。支持长征五号的上层是远征二号。

Long March 5 is a series of multi-purpose rockets. When carrying out high orbit and deep space exploration missions, it also needs to carry the third stage, or upper stage, which is similar to the effect of a space ferry. The upper level supporting the Long March 5 is expedition 2.

在航空航天领域，一颗arrown卫星"撒土豆"的现象并不少见，因为只有几十克重的pico卫星也叫卫星。然而，一次将多颗高质量卫星送入不同轨道非常复杂，对上一级的要求也很高。例如，在北斗建设过程中，远征一号多次使用，实现了一箭两星的任务，节省了发射次数。而"远征二号"在中国航天事业的上层实现了新的重大突破。首款双引擎设计还使其具有非常强的机动变轨能力，比"远征一号"更强，可以帮助飞船进入更远、更高、更复杂的轨道。

In the field of aerospace, it is not uncommon for one arrow n satellite to "scatter potatoes", because the pico satellite, which weighs only tens of grams, is also called a satellite. However, it is very complicated to launch multiple high-quality satellites into different orbits at one time, and the requirements for the upper stage are very high. For example, in the process of Beidou construction, expeditionary-1 was used several times to realize the mission of one arrow and two satellites, saving the number of launches. And expedition 2 has achieved a new major breakthrough in the upper stage of China's space industry. The first dual engine design also enables it to have a very strong maneuvering orbit changing capability, which is stronger than expedition 1 and can help the spacecraft enter a farther, higher and more complex orbit.

新外壳、新结构、新模块组合

New shell, new structure and new modular combination

在航空航天领域有一个著名但不失真的"笑话"——"马屁股决定运载火箭的运载能力"。其主要思想是，原来的铁路设计是指宽度马对接并排。轨道宽度决定了车厢的设计宽度，车厢设计宽度决定了隧道设计宽度，隧道设计宽度决定了火箭的最大允许直径，火箭的尺寸自然决定了火箭的最终运载能力。

There is a famous but undistorted "joke" in the aerospace field - "horse butt determines the transport capacity of the carrier rocket". The main idea is that the original rail design referred to the width of horse butt side by side. The rail width determines the design width of the carriage, the carriage design width determines the tunnel design width, and the tunnel design width determines the maximum allowable diameter of the rocket, The size of the rocket naturally determines the final transport capacity of the rocket.

最终的结果是，历代主力长征火箭的最大壳体直径一般为3.35米，无论多宽，都无法运送到三个发射中心（酒泉、太原、西昌）。

The final result is that the largest shell diameter of the previous main long march rocket is generally 3.35 meters, no matter how wide it is, it cannot be transported to the three launch centers (Jiuquan, Taiyuan and Xichang).

大工匠：高凤林图片来源：中央电视台

Great Craftsman: Gao Fenglin, photo source: CCTV

为满足运力提升的需求，长征五号要求箭体直径为5米。除第一级外，还捆绑了4台3.35米的助推器，总质量已飙升至869吨，远远超过长征3B系列的426-459吨[2]。它已成为名副其实的"肥五"，意味着全新的外壳和整体结构设计方案。至于它的难度，我们建议读者观看著名的纪录片《大国工匠》。第一集讲述了焊接火箭发动机和大型炮弹的大国工匠高凤林的故事。

In order to meet the demand of transportation capacity improvement, the Long March 5 is required to have a 5-meter-diameter arrow body. Besides the first stage, four 3.35-meter boosters are bundled, and the total mass has soared to 869 tons, far exceeding the 426-459 tons of the Long March 3 B series [2]. It has become a veritable "fat five", which means a brand-new shell and overall structural design scheme. As for its difficulty, we recommend readers to watch the famous documentary "craftsman of great powers". The first episode tells the story of Gao Fenglin, a craftsman of great powers who welded rocket engines and large shells.

此外，长征五号还实现了大型火箭的模块化设计理念。火箭级、是否搭载上一级、助推器捆绑方案可根据发射要求改变，从而衍生出适合各种任务的长征五号族。

In addition, the Long March 5 has also realized the modular design concept of large rockets. The rocket stages, whether to carry the upper stage or not, and booster binding scheme can be changed according to the launch requirements, thus deriving a long March 5 family suitable for a variety of tasks.

新配套发射场、运载火箭和生产基地

New supporting launch site, rocket carrier and production base

但是，长征五号显然不能再使用三个传统的火箭发射场，需要新建一个火箭发射场，那就是海南文昌火箭发射基地。事实上，它还有两大优势：它被海洋包围，火箭碎片不会造成任何破坏；低纬度地区可以更多地利用地球自转的力量，减少推进剂消耗，提高运输能力。

However, it is obvious that long March 5 can no longer use the three traditional rocket launching sites, and a new rocket launching site needs to be built, which is Wenchang rocket launching base in Hainan. In fact, it has two other major advantages: it is surrounded by oceans, and the debris of the rocket will not cause any damage; The lower latitude can make greater use of the power of the earth rotation to reduce propellant consumption and improve transport capacity.

远望21号和22号航天飞机

Yuanwang 21 and 22 space carriers

2019年底，长征五号发射试飞圆满成功。当时，为了把长征五号运到文昌，中国还为两艘远望21/22号航母服务；为了将组装好的火箭转移到发射台上，需要建造一个大型专用火箭运输平台；长征五号的生产装配在天津滨海新区完成（天津航天长征火箭制造有限公司），这也将成为中国未来火箭生产体系的灵魂。

At the end of 2019, the launch flight test of Long March 5 is a complete success. At that time, in order to transport the Long March 5 to Wenchang by sea, China also served two Yuanwang 21 / 22 space carriers; In order to transfer the assembled rocket to the launching pad, it is necessary to build a large special rocket transportation platform; The production and assembly of Long March 5 are completed in Binhai New Area of Tianjin (Tianjin Aerospace long march rocket Manufacturing Co., Ltd.), which will also become the soul of China's future rocket production system.

这些只是长期五年规划的一部分，但已经可以想象，每一点的背后，都有无数常年攻坚克难的科研人员，也需要国家强大的人力物力、科研和工程技术实力作为后盾。

These are only part of the long-term five-year plan, but it is already conceivable that behind each point, there are countless scientific researchers who have overcome difficulties all the year round, and also need the strong human and material resources, scientific research and engineering and technical strength of the country as the backing.

启航，梦想九天！近日，长征5B遥二号运载火箭将承担中国空间站核心舱发射任务。预祝中国空间站核心舱发射成功！

Set sail, dream nine days! Recently, the long march 5B tele2 carrier rocket will undertake the mission of launching the core module of China's space station. I wish the launch of the core module of China's space station a success!

Link：https://new.qq.com/omn/20210428/20210428A09TJX00.html

update time：2021-04-28 17:59:27