Xinhua News Agency, Hainan, Wenchang, May 29th, title: Flying Tianzhou under the moon-full interpretation of the Tianzhou 2 mission
Xinhua News Agency reporters Li Yun, Zhang Minmi, Zhao Yeping, Zhang Quan
Wenchang, China, the South China Sea at night, full moon in the sky.
At 20:55 on May 29th, Beijing time, the Long March 7 Yaosan carrier rocket carrying the Tianzhou-2 cargo spacecraft was ignited and launched at the Wenchang Space Launch Site in Hainan Province.
About 604 seconds later, the spacecraft and the rocket successfully separated and entered the intended orbit accurately.
At 21:17, the two wings of the solar panel started to work smoothly, and the launch was a complete success.
The soldiers and horses have not moved, the food and grass go first.
Thirty days after the launch of the Tianhe core module, China successfully sent the first express "parcel" to the core module of the space station.
"Popeye" lifts deep space dreams
Compared with the down-to-earth and cute "Fat Five"-the Long March 5 launch vehicle, the Long March 7 Yaosan launch vehicle looks slender.
But in fact, it has a total length of 53.1 meters, which is more than 3 meters shorter than the "Fat Five".
As a new generation of high-reliability and high-safety medium-sized liquid carrier rocket, the Long March VII is tailor-made to meet the exclusive needs of carrying the Tianzhou series of cargo spacecraft.
Because of its "two and a half levels" configuration, it is more symmetrical than the "1 and a half" configuration of "Fat Five"—if "Fat Five" is like a weightlifter, Long March 7 is even more symmetrical. Like a coach in a gym.
"Great strength" is the most basic requirement for the Long March 7 rocket in the construction of the space station.
Although not as graceful as the "Fat Five" posture, the Long March 7 has a take-off weight of 597 tons and a low-Earth orbit carrying capacity of 13.5 tons, making it one of the "Four Hercules" of Chinese rockets. It is a veritable "Popeye", reaching It has reached the advanced level of similar foreign rockets.
The mission of the "Popeye" this time is to send the Tianzhou-2 cargo spacecraft loaded with large quantities of materials to the scheduled orbit.
In order to be "stronger", Long March 7 uses more powerful liquid oxygen kerosene as fuel, and also compresses the installation gap of the booster main binding structure from 5 mm to 4 mm. This not only reduces the vibration of the rocket during flight, but also Increased boosting power.
"Success is our only option." Looking back on the development process of Long March 7, Rocket Chief Designer Cheng Tangming used this sentence to express his confidence and determination.
Since the official launch of the development project, the Long March 7 team has aimed at the construction of the space station, with the spirit of "arrowing" excellence and the foolproof rigorous style, and going all out to fight for mission and honor.
On June 25, 2016, the Long March 7 successfully flew for the first time at the newly constructed Wenchang Space Launch Site.
On April 20, 2017, the Long March 7 lifted into the sky with the Tianzhou-1 cargo spacecraft.
This is the first flight test of the space station cargo transportation system composed of the Tianzhou cargo spacecraft and the Long March 7 carrier rocket.
This time, the Long March VII successfully lifted off again, sending living materials, experimental facilities, and propellant to the space station’s sky and core module, and won another important link in the construction of China’s space station.
According to the space station’s orbit construction mission plan, by the end of 2022, my country will implement 11 consecutive launch missions, of which 4 cargo spacecraft launches will be "carried" by the Long March 7 rocket.
"Interlocking links, like a relay race, the success or failure of each mission depends on the smooth implementation of the China Space Station construction plan." said Xu Lijie, the chief designer of the Long March 7 launch vehicle test team.
In order to ensure the carrying capacity and meet the needs of rendezvous and docking, the scientific research team carried out a large number of optimization and improvement designs for the Long March 7 rocket, and carried out "re-analysis, re-design, and re-verification" around technical status confirmation and key link assurance. More than 100 changes have taken place in the state of technology.
In order to meet the need for rendezvous and docking between the spacecraft and the space station, the scientific research team expanded the launch "zero window" accurate to the second to a "narrow window" of about 2 minutes.
In layman's terms, if the rocket's take-off time has a deviation of less than 2 minutes, the rocket can correct its flight trajectory according to the take-off time to ensure that the cargo spacecraft can still enter the orbital surface where the core cabin is located, laying the foundation for subsequent rendezvous and docking.
Careful people will find that at the moment the rocket ignited, the red “smoke” formed by the insufficient combustion of nitrous oxide did not appear on the tail of the “Popeye”. Instead, it was replaced by “white smoke” like cotton candy.
That's because the Long March VII is equipped with a new type of liquid oxygen kerosene engine with independent intellectual property rights. When kerosene is not fully burned, the particles and water vapor produced are mixed and condensed, and the "smoke" formed is white.
With this technical improvement alone, the thrust of the Long March 7 has increased by 60%.
"Brother Express" travels through the corridors of heaven and earth
There are more than 160 large and small packages, two astronaut outer suits weighing more than 100 kilograms each, and 3 tons of propellant. The Tianzhou-2 cargo spacecraft is not the largest cargo spacecraft in the world, but it contains materials. However, it reached 6.8 tons, which exceeded the weight of the spacecraft.
Far away from the earth, the food, clothing, and supplies needed for breathing in the space station must be delivered by the cargo spacecraft in time.
The Tianzhou cargo spacecraft and the Long March 7 rocket together constitute the space station's cargo transportation system, realizing the "reloading of people and cargo," and becoming the "courier brother" in China's manned space project.
When "going", Tianzhou-2 can deliver various living materials, propellants, platform maintenance equipment accessories, various consumables, load equipment and other supplies to the space station.
When it "returns", Tianzhou-2 will also take away and destroy space station waste.
Compared with Tianzhou-1, Tianzhou-2 is basically the same in configuration, adopting a two-chamber configuration composed of a fully sealed cargo compartment and a propulsion compartment, with a total length of 10.6 meters and a maximum diameter of 3.35 meters.
In terms of the tasks undertaken, Tianzhou-2 has its own distinctive features.
In order to install more, the scientific research team designed a total of 26 different sizes and different shapes of cargo packages based on the circular cabin structure of the cargo spacecraft, which are combined and placed into the cargo compartments formed by honeycomb panels like building blocks. .
Each package is firmly secured by a safety lock similar to an airplane seat and can be removed with one hand.
These materials can meet the needs of three astronauts living in space for three months.
Not only is it loaded more, but it is delivered quickly.
The fast interactive docking system of Tianzhou 2 has arranged the action sequence after entering orbit in advance, which saves the time for transmitting instructions between the sky and the earth, and also eliminates the process of temporary injection procedures on the ground, from “delivery” on the ground to “express delivery”. "Brother" knocked on the door for about 7 hours, which was comparable to "same city express" and realized the rapid replenishment of space station mission materials.
Not only the delivery is fast, the Tianzhou-2 has also designed a number of "fuel tanks" isolated from the airtight cabin, and has "hazardous goods transportation qualification".
In addition to transporting living materials and experimental facilities, Tianzhou-2 also carried 3 tons of propellant. After the rendezvous and docking, it became a "gas station" for the space station.
Not only can refuel, but also recharge the space station.
The Tianzhou-2 cargo spacecraft has its own independent energy system, which can achieve energy self-sufficiency.
During berthing at the space station, Tianzhou 2 and the space station can transmit complementary power resources to each other. During berthing, Tianzhou 2 is in a dormant state, and its own energy demand is small, and the surplus electric energy can be transported to the space station for aerospace. Staff activities provide guarantee, while supporting some scientific experiments that consume a lot of electricity.
Tianzhou 2 is also a "storage room".
After completing the rendezvous and docking, the astronauts will go in and out of the Tianzhou-2 to obtain living and working materials.
In order to allow astronauts to easily and quickly access and find the materials they are looking for in the sky, each piece of goods in the "storage room" is pasted with a radio frequency identification tag, which can be used for intelligent positioning using special equipment. .
Tianzhou-2 has the function of storing garbage and is a space "trash can".
The domestic garbage and human excrement produced by the astronauts in the space station will be concentrated in the Tianzhou-2 capsule for storage.
After completing its mission, Tianzhou-2 will take away these wastes and burn them together as they fall into the atmosphere.
With a cargo loading volume of 18 cubic meters, in addition to leaving space for activities in the astronaut cabin, it also has so many functions and maintains a balanced weight. The scientific research team has used a lot of wisdom in the layout design.
Strong delivery and replenishment capabilities will also play a major role in extending the life of the space station and astronauts staying in orbit.
In a while, Chinese astronauts will take the Shenzhou 13 manned spacecraft to space.
It is believed that the moment they open the door of the Tianzhou-2 cargo spacecraft after entering the Tianhe core cabin, there will be a surprise of "demolition of express delivery".
"Binhai Fudi" continues to write a new chapter in aerospace
Before the launch site was built, Wenchang, Hainan was known as the hometown of overseas Chinese. More than 1.2 million overseas Chinese with Wenchang ancestry lived in more than 50 countries and regions in the world.
In history, Wenchang was also a cultural hometown of "one mile and three jinshi", a hometown of generals where more than 200 high-ranking military generals were born.
Because it faces the sea on three sides and the content of negative oxygen ions is high, the average life expectancy of Wenchang residents is as high as 81.85 years. It is a blessed place for outstanding people.
In August 2007, my country decided to build a new generation of the most advanced space launch site in Wenchang, Hainan.
In September 2009, Wenchang Aerospace Launch Site broke ground in Longlou Town, Wenchang City.
Following the three major launch sites in Jiuquan, Taiyuan, and Xichang, the Wenchang Space Launch Site was fully completed and put into use in 2016, and Wenchang, the "Blessed Land on the Sea", has another reputation as a "Space City".
As China’s first open coastal space launch site and one of the few low-latitude launch sites in the world, the Wenchang Space Launch Site is mainly responsible for geosynchronous orbit satellites, massive polar orbiting satellites, large-tonnage space stations, and deep space exploration satellites. Launch mission of the aircraft.
In the past five years, Tianzhou-1, Tianwen-1, Chang'e-5, Tianhe core module, Tianzhou-2... all major powers have flown into space from here.
This time, Wenchang Aerospace personnel fought hard under pressure and moved forward in perseverance. In accordance with the requirements of "to ensure foolproof and complete success", strictly implement the quality standards of manned space projects, organize comprehensive inspections of launch areas, and comprehensively inspect equipment and facilities. Dozens of drills have been organized for the preparation of special combustion, special gas, materials and equipment, and only propellant refuelling, rescue and fire rescue exercises.
Space launch is a high-risk scientific and technological activity.
The launch mission of Tianzhou-2, originally scheduled for the early morning of May 20th, was postponed due to technical reasons, and the launch site system was under considerable pressure.
Compared with the traditional launch mission, the launch mission of Tianzhou-2 not only needs to accurately send the spacecraft into the predetermined orbit, but also launch the cargo spacecraft into the space orbit plane where the Tianhe core module is located, so as to realize the cargo spacecraft and the Tianhe core module. Rendezvous and docking.
Once the rocket's take-off time deviates from the launch window, it will miss the orbital surface where the space station is located, causing the cargo spacecraft to require a longer orbit adjustment, consume more propellant, and even affect the rendezvous and docking mission.
In order to ensure that the launch mission is carried out within the established window time, the meteorological support personnel of the Wenchang Space Launch Site have strengthened technical research on lightning, heavy precipitation, shallow wind, and high-altitude wind, and collected and sorted out the meteorological data of the site for the past 15 years. The "narrow window" launch of No. 2 provides time-sharing segmentation, fine and accurate weather protection.
The launch site has a short-term forecast accuracy rate of more than 95%, and it has the ability to forecast the weather on the launch day 7 days in advance and the weather in the window 8 hours in advance.
The Long March 7 rocket is a type of cryogenic propellant rocket.
The low-temperature propellant has a large amount of evaporation. In order to ensure the carrying capacity and engine starting conditions, a series of complicated actions need to be carried out before launching. Any abnormality in any link will affect the launch.
On May 16, after the ship-and-arrow assembly was transferred to the launch area, the launch site was operated at full capacity day and night, deployed to strengthen unified leadership, strengthen organization and command, continuous resource protection, major risk prevention and control, final assembly, testing, joint training...
The high-intensity launch mission has also honed a group of young technical backbones into talents. A group of "highly educated", "good decision-making" and "capable" scientific and technological talents are active in the forefront of space launch and become the support of the aerospace industry.
"Assume three consecutive major space launch missions within 3 months, and the comprehensive test launch capability of Wenchang Space Launch Site has been continuously improved." Dong Chongqing, Secretary of the Party Committee of Xichang Satellite Launch Center, said that Wenchang Space Launch Site has low latitude and high launch efficiency. With wide shooting range, good safety, convenient shipping, strong feasibility, non-toxic, non-polluting, and environmentally friendly, it has unique advantages and can be an important task in the journey of building a powerful aerospace country.