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"3, 2, 1, ignition!"
At 1:56 a.m. today, the Tianzhou-4 cargo spacecraft broke through the night sky at the Wenchang Cosmodrome and was successfully launched.
The one who completed the "lifting" work this time was the Long March 7 Yaowu carrier rocket.
It was also the first time it had been able to complete testing and launching in one month (27 days) – "the rocket's test and firing cycle was reduced by 4 days compared to the Tianzhou III mission."
After about 10 minutes, the spacecraft successfully separated from the rocket and entered a predetermined orbit.
At 2:23, the solar panels of the spacecraft began to work smoothly. At this point, the launch mission can be said to be a complete success.
At 8:54, the Tianzhou-4 cargo spacecraft successfully rendezvoused and docked with the space station assembly operating in orbit.
The successful launch of the Tianzhou-4 cargo spacecraft, the meaning behind it is not only "the successful delivery of 'Space Express'", as CCTV commented:
This is the 22nd launch mission of the mainland manned space project and the 420th flight of the Long March series of carrier rockets.
At this point, the curtain on the construction stage of The Chinese space station has officially opened.
"Space Express", successfully shipped
Let's first understand the "courier brother" of Tianzhou No. 4.
It is 10.6 meters tall, 3.35 meters "waist circumference" and weighs 13.5 tons.
△ Source: Xinhua Net
Although the launch of Tianzhou-4 was the fourth expedition of the space station's cargo transportation system, it was the first launch of the continental space station construction phase.
And the task it has to perform is also very obvious - to help the "God Fourteen" multiply the group to carry goods.
Because astronauts need to be stationed on the space station for a long time, and the materials they need to eat, wear, use and even breathe need to be sent to the space station in time by cargo spacecraft to maintain.
It is understood that the Tianzhou-4 was loaded with a total of more than 200 pieces of cargo, covering astronaut systems, space station systems, space applications and cargo spacecraft systems.
These include cargo parcels and direct installation cargo, carrying about 750 kg of retro-propellant and a total load of about 6,000 kg of uplink material.
These goods will provide material support for the 3-month on-orbit residence of Shenzhou 14 crew, the assembly and construction of the space station, the development of material science, microgravity, aerospace medical experiments and other space applications.
In order to make this batch of "express delivery" safely delivered, Tianzhou-4 adopts a variety of cargo loading methods such as bags, brackets, and storage boxes, and the types and quantities of goods can be dynamically configured according to the needs of the space station.
At the same time, it also has the ability to undertake space station operation support tasks such as space station attitude orbit control, grid-connected power supply, space station telemetry, data transmission support, and space science experiment support.
But just like the number of this "courier brother", there are actually three "predecessors" before it, namely Tianzhou No. 1, Tianzhou No. 2 and Tianzhou No. 3.
The first order to send out the "Space Express" is the "Big Brother" Tianzhou No. 1.
On April 20, 2017, he "piloted" the Long March 7 Yao-2 carrier rocket "to" Tiangong-2, with a cargo capacity of 6.5 tons.
Tianzhou-1 completed its first docking with Tiangong-2 on April 22, 2017, and completed its mission on September 22, 2017, entering the atmosphere and burning.
The "second brother" Tianzhou-2 was launched on May 29, 2021, and its "car" is the Long March 7 Yaosan carrier rocket, and completed the autonomous rapid rendezvous and docking with the Tianhe core module on May 30.
Tianzhou-2 "served" for nine months and was controlled into the atmosphere on March 31 this year.
On September 20, 2021, the "three brothers" Tianzhou-3 "piloted" the Long March 7 Yao-4 carrier rocket and launched into the air, and completed rendezvous and docking with the Tianhe core module and the Tianzhou-2 combination.
(Note: Tianzhou-2 has previously separated from the space station Tian and the rear port of the core module, and flew around to the forward port to complete the automatic rendezvous and docking)
Tianzhou-3 is still sticking to the post, and the docking of Tianzhou-4 will be the same as the "second brother" and "third brother" collaborative work mode at that time.
That is, one at the head and one at the end, jointly guarding the sky and the core cabin.
This is the whole picture of the mainland's "space courier" - the "family" of Tianzhou.
Then, it is necessary for us to understand the "car" of this cargo spacecraft - the Long March 7 carrier rocket.
The number of days of detection and detection is compressed to 27 days
The Long March 7 carrier rocket is a new generation of medium-sized carrier rockets on the mainland, developed by the First Academy of The Aerospace Science and Technology Group.
It is a two-and-a-half-stage, all-liquid oxygen kerosene propellant rocket capable of sending a 14-ton payload into low-Earth orbit that can rendezvous and dock with the Chinese space station.
As just mentioned, the "cars" of "space couriers" are different, from "big brother" to "three brothers", which are remote two, remote three and remote four.
So what is the difference between the Long March 7 Yaowu carrier rocket that lifted tianzhou-4 this time?
According to China Aerospace News, the Long March 7 carrier rocket has 17 technical status improvements, and the China Beidou satellite navigation system has been upgraded to the first priority of satellite positioning, and the flight reliability of the rocket has been increased to 0.9838, reaching the world's advanced level.
At the same time, the Long March 7 carrier rocket test team optimized the test and development process and reduced the number of test and launch days to 27 days.
For the first time, the parallel filling of liquid oxygen and kerosene propellants was realized, and the pre-launch working time was shortened by one-third, which effectively improved the work efficiency of the launch site.
Not only that, according to the People's Daily, in order to cope with Hainan's humid, hot, rainy, and frequent typhoons, the Long March 7 rocket has an all-weather launch capability and can be parked for 24 hours after the low-temperature fuel is refueled.
As Zhu Pingping, a rocket design expert in the General Department of the Rocket Institute, said:
The new generation of carrier rockets represented by the "Long Five" and "Long Seven" are liquid hydrogen, liquid oxygen and liquid oxygen, and kerosene, which are all low-temperature fuels.
The temperature of liquid hydrogen reaches minus 253 degrees Celsius, and the temperature of liquid oxygen reaches minus 183 degrees Celsius. Liquid hydrogen and liquid oxygen combustion produce water, non-toxic and non-polluting, and greatly improve the carrying capacity of the rocket.
Up to now, with the successful launch of Tianzhou-4, the number of launches of the Long March series of carrier rockets has reached 420 times.
But more importantly, it also means that the curtain has officially opened on the construction phase of the Chinese space station.
The crucial battle to achieve the "three-step" strategic goal of the mainland's manned space project has already begun.
Reference Links:
[1]https://finance.sina.com.cn/tech/2022-05-10/doc-imcwipii8960092.shtml
[2]https://m.jxnews.com.cn/news/system/2022/05/10/019628964.shtml
[3]http://www.news.cn/politics/2022-05/10/c_1128635577.htm
[4]https://baijiahao.baidu.com/s?id=1732399917199169303
[5]https://baike.baidu.com/item/%E5%A4%A9%E8%88%9F%E4%B8%80%E5%8F%B7/15727980?fr=aladdin