What else do you know about shenzhou spaceship?

Release time:

1October 20th1999165438+6: 30: 7.

Launch a rocket:

The launch of the new Long March II F-bound rocket is the 59th flight of the Long March series of launch vehicles, and it has been successful 17 times in the last three years.

Time required for spacecraft to enter orbit;

The rocket took off about 10 minutes, and the spacecraft separated from the rocket and entered the scheduled orbit.

Return time:

1999165438+1October 2 1 3: 00 4 1.

Launch site:

Jiuquan Satellite Launching Center

Landing place:

Central Inner Mongolia Autonomous Region

Flight time/laps:

2 1 hour 1 1 minute/14 laps

Carry items:

First, flags, such as those of National Flag of the People's Republic of China, regional flag of the macao special administrative region and the Olympic Games; Second, various stamps and souvenir covers; Third, the seeds of crops such as green pepper, watermelon, corn and barley, and seeds of Chinese herbal medicines such as licorice and isatis root are about 10g.

Technical application:

For the first time, a new model of spacecraft and rocket assembly with vertical assembly test in technical workshop, vertical transportation to launch site and remote test and launch control was adopted. On the basis of the original TT&C network, a new land-based TT&C network in China, which conforms to the international standard system, was put into use for the first time in this launch test. During the spacecraft's on-orbit operation, the ground monitoring and control system and four "Roy" survey ships distributed on the high seas tracked and monitored it, and successfully carried out a series of scientific experiments.

Shenzhou II

Release time:

200 1 year 1 month 10 day 1 hour, 0 minutes and 3 seconds

Launch a rocket:

The launch of the new Long March II F carrier rocket is the 65th flight of the Long March series of launch vehicles and the 23rd consecutive successful space launch in China since 19961October.

Time required for spacecraft to enter orbit;

After the spacecraft takes off 13 minutes, it will enter the scheduled orbit.

Return time:

200 1 1 16 7: 22 pm

Launch site:

Jiuquan Satellite Launching Center

Landing place:

Central Inner Mongolia Autonomous Region

Flight time/laps:

6 days 18 hours/108 laps

Test project: China's first unmanned spacecraft prototype. Spacecraft consists of orbital module, return module and propulsion module. Compared with Shenzhou-1 experimental spacecraft, the system structure of Shenzhou-2 spacecraft has been expanded, its technical performance has been improved, and its technical status is basically the same as that of manned spacecraft. According to reports, China has conducted experiments in the fields of space life science, space materials, space astronomy and physics for the first time in microgravity environment, including: crystal growth of semiconductor photoelectric materials, oxide crystals, metal alloys and other materials; Protein and other biomacromolecules grow in space crystals. Experiments on the spatial environmental effects of plants, animals, aquatic organisms, microorganisms and isolated cells and tissues were carried out.

Shenzhou III

Release time:

22: 00 on March 25th, 200215.

Launch a rocket:

The launch of the new Long March II F-bound rocket is the 66th flight of the Long March series of launch vehicles. Since 1996 10, China's launch vehicle has been successfully launched for 24 consecutive times.

Time required for spacecraft to enter orbit;

After the rocket ignited 10 minutes, the spacecraft successfully entered the scheduled orbit.

Return time:

April 2002 1 day.

Launch site:

Jiuquan Satellite Launch Center.

Landing place:

Central area of Inner Mongolia Autonomous Region.

Flight time/laps:

6 days 18 hours/108 laps.

Carry items:

Black eggs in a dormant state; There are 44 public payloads 10 for space experiments, including: cirrus detector, medium resolution imaging spectrometer, earth radiation budget meter, solar ultraviolet spectrum monitor, solar constant monitor, atmospheric density detector, atmospheric composition detector, spacecraft orbital module window assembly, cell bioreactor, multi-task space crystal growth furnace, space protein crystallization device, solid track detector, microgravity measuring instrument and payload public equipment. According to reports, the microgravity measuring instrument and the return capsule payload public equipment are participating in the spacecraft test for the third time; The space protein crystallization device, multi-mission space crystal growth furnace and orbital module payload sharing equipment are the second time to participate in the spacecraft test; The rest of the equipment was tested in space for the first time.

Test project: "Shenzhou III" is a prototype unmanned spacecraft, and the technical state of the spacecraft is completely consistent with the manned state. This launch test further improved the launch vehicle, spacecraft and TT&C launch system, and improved the safety and reliability of manned space flight. The spacecraft is equipped with human metabolism simulator, anthropomorphic physiological signal equipment and human dummy, which can quantitatively simulate the important physiological activity parameters of astronauts in space. Launch, escape and life-saving systems also played a role. This system is the main measure to ensure the safety of astronauts in an emergency. The physiological signals and metabolic indexes provided by the anthropomorphic load of the spacecraft are normal, which verifies the in-cabin environmental control and life support system directly related to manned space flight.

Shenzhou IV

Release time: February 30, 2002 10:40.

Launch rocket: The new Long March II F-bound rocket is the 69th flight of the Long March series of launch vehicles, and it is also the 27th consecutive successful space launch in China since 1996+00.

Time required for the spacecraft to enter orbit: Ten minutes after the rocket was ignited and lifted off, the spacecraft successfully entered the scheduled orbit.

Return time: 20031October 5th, 65438+ 19:00+06:00.

Launch site: Jiuquan Satellite Launch Center

Landing place: Central area of Inner Mongolia Autonomous Region

Flight time/laps: 6 days 18 hours/108 laps.

Carry-on items: Except for the atmospheric composition detector and other 19 pieces of equipment that have participated in the previous flight test, 33 pieces of scientific research equipment, such as other space cell electrofusion instruments, will "go to heaven" for the first time. Two pairs of "cell space weddings" that have been prepared for 10 years will also be held on the spacecraft. One pair of animal cell "newcomers" are B lymphocytes and myeloma cells, and the other pair is plant cell "newcomers"-tobacco protoplast of Huanghua and tobacco protoplast of Innovation No.1.. Experts say that under microgravity conditions, the gravity settlement of cells in the fusion solution will disappear, which is more conducive to the "intimate action" of cell pairing and fusion. This study will explore new methods for aerospace pharmacy.

Shenzhou v

Launch time: 20031October 15 at 9: 00.

Launch rocket: the new Long March II F-bound rocket, which is the 7th flight of Long March series launch vehicles and the 29th consecutive successful launch of China Aerospace since 1996 10.

Flight time required for the spacecraft to enter orbit: 9: 00/kloc-0: 00, the ship and the arrow are separated, and the "Shenzhou 5" manned spacecraft accurately enters the scheduled orbit.

Return time: 20031October 16 at 6: 28.

Launch site: Jiuquan Satellite Launch Center

Landing place: Gulang Grassland, A Mu, Central Inner Mongolia.

Flight time/laps: 2 1 hour/14 laps.

Articles carried: In addition to Yang Liwei, the first man in manned space flight in China, the return capsule of Shenzhou 5 manned spacecraft also carried a special flag of China, the flag of Beijing 2008 Olympic Games, the United Nations flag, samples of major currencies of RMB, stamps commemorating China's first manned space flight, a souvenir cover of China's manned space flight project and crop seeds from Taiwan Province Province, the treasure island of the motherland.

Test items: Shenzhou 5 will reduce the number of in-cabin test items and instruments as much as possible to make more space for astronauts to carry out scientific observation tasks. It can be said that this task is mainly to examine the adaptability of astronauts in the space environment.

Application of new technology: automatic fault detection system and escape system are added for the first time. Among them, there are hundreds of failure modes, which will automatically alarm in case of danger. Even after the launch of the spacecraft for a period of time, you can get out of danger by avoiding the rocket.

Shenzhou VI

Launch time: 20051October 12 at 9: 00: 00.

Launch rocket: Shen Jian-Long March II F carrier rocket.

Flight time required for spacecraft to enter orbit: 584 seconds.

Return time: 65438+1October 17 at 4: 32 am.

Launch site: Jiuquan Satellite Launch Center

Landing place: autumn rhyme of Siziwang grassland

Flight time/laps: 1 15 hours, 32 minutes /77 laps.

Carry-on articles: 64 kinds of carry-on articles in 8 categories, including logos of well-known enterprises such as Goldlion and Cha Group in Hong Kong. Space breeding experiments were carried out by using biological strains, plant tissue culture seedlings and seeds of crops, plants and flowers. At the opening ceremony, six special "passengers" had the opportunity to make a wonderful appearance. They are the national flag of China, the flag of the International Olympic Committee, the flag of the Shanghai World Expo, the centennial special issue of Shenbao, the painting and calligraphy work Six Horses, and 65,438+00 space paintings by young pioneers. The articles carried by Shenzhou VI return capsule also include the composition of "I wrote a letter to Shenzhou VI astronauts", the special stamps of the Marshal of the Republic and the personalized stamps of Shenzhou VI, and the works of famous painters and painters.

Technical application: There are many kinds of spacecraft, but the most commonly used one is satellite manned spacecraft. This kind of spacecraft, like a satellite, flies in low-earth orbit hundreds of kilometers from the ground, with a flying height of about 300 kilometers. There are three types of spacecraft: single cabin, double cabin and triple cabin. At present, the spaceships of mature spacefaring countries in the world are all three cabins. This Shenzhou VI is a three-cabin spacecraft, which shows that China's space technology has initially reached the international level.

Shenzhou VI spacecraft has the following characteristics: first, the starting point is very high, and the spacecraft has the ability to carry three astronauts;

Secondly, one boat can be used for many purposes. After the astronauts return, the orbital module can be used as a satellite for half a year unattended, and even rendezvous and docking experiments can be carried out in the future. Third, the return capsule has a large diameter, 2.2 meters in Russia and 2.5 meters in China. Finally, the return of the spacecraft is very safe, which has been fully tested. Generally speaking, the technological progress of Shenzhou VI spacecraft is enormous.

Technical progress is mainly reflected in the following aspects: First, in the field of new materials, it is reported that more than 2,000 kinds of progress in the field of new materials in China in recent years have come from the aerospace field; Secondly, in the field of telecommunications, both hardware and software have made progress. For example, coding technology can ensure voice quality and image clarity. The third is image technology, which can be used in both military and civilian fields. The fourth is special food, and the food development of astronauts is very complicated; The fifth is special textile materials, and spacesuit is the crystallization of a system and high technology; The sixth is the progress of electronic control system. Spacecraft is a complex system involving various complex subsystems, and all systems need to be controlled by electronic control system. Seventh, the progress of biomedical system. There are essential differences between manned space flight and unmanned space flight, and the complexity and reliability of the system are also very different. The success of Shenzhou VI shows that China has made great progress in related biomedicine.

Shenzhou VI spacecraft is still a three-room structure of propulsion module, return module and orbital module. The shape and structure of the whole ship are the same as the original, and the weight is basically maintained at about 8 tons. After the spacecraft entered the orbit, it first circled five times in an elliptical orbit with a perigee of 200 kilometers and an apogee of 350 kilometers, and then changed its orbit to a circular orbit with a distance of 343 kilometers from the ground. After flying around the earth for 90 minutes, the flight trajectory projected on the ground moved eastward in a sinusoidal curve. Orbit features are the same as those of Shenzhou 5.

Because there was no rendezvous and docking mission on this flight, Shenzhou VI cancelled the additional segment for this function. In addition, the spacecraft added more than 40 devices and 6 softwares, making the number of devices and 82 softwares more than 6.5438+million.

The improvement of Shenzhou VI can be roughly summarized into four aspects:

First, around the improvement of the multi-day task of two people. First of all, we have prepared enough or even excess astronaut consumables, including food, water and sleeping bags. The food cabinet was put in the orbital module, which was empty before. According to the water consumption of one and a half thermos bottles per person per day, the astronauts' water is prepared with water tanks and separate soft packages. Secondly, the environmental control ability of the cockpit is improved. A person exhales nearly a liter of water a day. Shenzhou VI improved the ability to condense water vapor, expanded the condensation water tank, and put water-absorbing materials on all exposed pipes to ensure that the humidity of the spacecraft was controlled below 80%. Oxygen, temperature and humidity in the cabin can be automatically sensed and adjusted.

Second, the improvement of the function and use of the orbital module. Astronauts have many necessities, such as food heating devices and tableware. There is a sleeping bag hanging in the orbital module for two astronauts to take turns to rest. In weightlessness, people can actually sleep in the air, but considering the habits of people on the ground, sleeping bags artificially create a feeling of "bed", otherwise astronauts may have the illusion of rolling in the deep when sleeping. There is also a special cleaning cabinet in the orbital module, and astronauts can clean it with items such as wet wipes. This is the first time to use the urine collector.

Third, improve the safety of astronauts. The astronaut seat of the return capsule is designed with landing buffer function, which is to ensure the safety of astronauts when the thrust rocket fails. The landing buffer function of the seat in Shenzhou 5 spacecraft has a small defect, that is, it is difficult for astronauts to see the situation outside the porthole before returning after the seat is lifted. Shenzhou VI redesigned the buffer and carried out repeated tests with the whole ship. The three tests dropped from the tower and the plane were successful every time. If the hatch between the return module and the orbital module is not tightly closed when returning, it will threaten the safety of astronauts. Three astronauts were killed in Russia. Shenzhou VI researchers have successfully developed a quick and automatic inspection device for cabin door seal, and developed a special rag for several months, which does not produce fiber, static electricity and odor, and is specially used for cleaning cabin doors.

Fourth, continuous improvement. China's manned spaceflight project was officially launched in 1992, and it has been 13 years. Some parts and raw materials originally used on the spacecraft are no longer produced, and some technologies are a bit outdated. Shenzhou VI made some daily continuous improvements. For example, the "black box" from Shenzhou I to Shenzhou 5 was developed in 1994, with a storage capacity of only 10 trillion. Nowadays, the storage capacity of the black box is not only 100 times larger than the original, but also the data reading and writing speed is increased by more than 10 times, but the volume is less than half of the original.

Composition of shenzhou spaceship

Orbital module: "multifunctional hall"

Shenzhou spaceship orbital module is a cylinder with a total length of 2.8m and a maximum diameter of 2.25m.. One end is connected with the return cabin, and the other end is connected with the space docking mechanism. Shenzhou VI's orbital module is called "multifunctional hall" because two astronauts are in the orbital module at other times except when taking off and returning. The orbital module integrates many functions such as working, eating, sleeping, washing and convenience.

Escape Tower: Ensure the safety of the spaceship.

Escape Tower: Located at the front of the spacecraft, it is 8 meters high. It is actually a small launch vehicle composed of a series of rocket engines. 900 seconds before the launch of the launch vehicle and 160 seconds after the launch? The running distance of the rocket ranges from 0 to 100 km. In case of emergency, this life-saving tower will be activated urgently, dragging the return module and orbital module of Shenzhou VI spacecraft away from the rocket, quickly escaping from the dangerous area and landing to safety through parachute.

Orbital module: the "home" of astronauts

Orbital module: also known as working module. Its shape is a cylinder with cone angles at both ends, which is the "space bedroom" and "workshop" for astronauts. It also has two functions: astronaut's living module and orbital experimental module, so it is also called orbital module. The orbital module is equipped with a variety of experimental equipment and instruments, which can be used for earth observation. On both sides, it is equipped with retractable large-scale solar cell panels, solar sensors, various antennas and various docking structures, which are used to convert solar energy into spacecraft energy and communicate with the ground. As an astronaut's "space bedroom", the environment of the orbital module is very comfortable, and the temperature in the module is generally between 17 and 25 degrees Celsius.

Return capsule: astronaut's "cab"

Return capsule: also known as cockpit, it is the "cab" of astronauts. It is a cabin for astronauts to travel to and from space. This is a closed structure with a hatch in front. After "Shenzhou VI" completed its mission around the earth, two astronauts will also return to Earth in the return capsule.

Propulsion module: also known as instrument module. Usually, propulsion system, power supply, track brake are installed, and oxygen and water are provided for astronauts. There are also main solar cell sails with an area of more than 20 square meters on both sides of the propulsion cabin.

Cabin introduction

Orbital module

Size: 2.8 meters long and 2.2 meters in diameter.

Shenzhou spaceship's orbital module is cylindrical. In order to make the orbital module get power when flying alone, solar cell wings are installed on both sides of the orbital module, and the area of each solar cell wing is 2.0×3.4 meters except triangle. When the orbital module flies freely, it can provide more than 0.5 kW of power. There are four groups of small propulsion engines at the tail of the orbital module, four in each group, which provide the spacecraft with auxiliary thrust and the ability to maintain orbital motion after the orbital module is separated; There is a circular hatch on the side of the orbital module near the return module, which provides a passage for astronauts to enter and leave the orbital module. However, the maximum diameter of the hatch is only 65 cm, and only agile and specially trained people can enter and exit freely. There is an observation window of the orbital module above the hatch.

The orbital module is the place where astronauts work and live after the spacecraft enters orbit. In addition to food, drinking water, urinals and other living devices, there are instruments and equipment for space applications and scientific experiments.

After the return module returns, the orbital module is equivalent to an Earth observation satellite or a space laboratory, and it will stay in orbit for about half a year. The utilization of orbital module is a major feature of China spacecraft. After the orbital module and the return module of Russian and American spacecraft are separated, they are generally abandoned.

re-entry module

Size: 2.00 meters long and 2.40 meters in diameter (excluding thermal insulation).

Shenzhou spaceship's return capsule is bell-shaped, with doors communicating with the orbital module. Put it back in the command and control center of the spacecraft in the cabin, there are seats for three astronauts to recline, and astronauts can sit in the take-off, ascent and return stages. Below the front of the seat is the instrument panel, manual joystick and optical sight. , showing the mechanical equipment status of the last system on the spacecraft. Astronauts use these instruments to monitor and control the work of the mechanical equipment on the spacecraft when necessary. Both the orbital module and the return module are closed cabins, with environmental control and life support systems to ensure that the cabin is filled with mixed gas of oxygen and nitrogen at atmospheric pressure, and the temperature and humidity are adjusted to a suitable range for human body, so as to ensure the life safety of astronauts during the whole flight mission.

In addition, two parachutes, the main parachute and the standby parachute, are installed in the cabin for landing. There are two circular windows on the side wall of the shenzhou spaceship return capsule, one for astronauts to observe the scene outside the window, and the other for astronauts to operate the optical sight to observe the spacecraft driving on the ground. The base of the return capsule is a metal frame sealed structure, on which the instruments and equipment of the return capsule are installed. The base is light and strong, which protects the return capsule from being burned by the hot atmosphere when it returns to the ground and enters the atmosphere.

Propulsion module

Size: 3.05 meters long, 2.50 meters in diameter and 2.80 meters in diameter at the bottom.

Shenzhou's propulsion cabin, also known as the equipment cabin, is cylindrical and contains the engine and propellant of the propulsion system, which provides the spacecraft with the power needed for attitude and orbit adjustment, braking and deceleration, as well as some equipment of power supply, environmental control and communication system. There are a pair of solar wings on both sides, and the area of the solar wings is 2.0×7.5 meters except the triangular part. Together with the battery wing of the front orbital module, the power generated will be three times that of Soyuz, exceeding 1.5 kW on average, which is almost equivalent to the power provided by the power supply of Fukang AX New Wave Automobile. In addition to providing a lot of power, these battery wings can also rotate around the connection point, so that no matter how the spacecraft moves, it can always maintain the best direction to obtain the maximum power, eliminating a lot of maneuvers of "leaning toward the sun", so that the spacecraft can keep observing the earth while ensuring that the solar array faces the sun.

At the back of the equipment cabin is the propulsion system of the spacecraft. The main propulsion system consists of four large main engines, which are located at the bottom center of the propulsion cabin. Four pairs of small thrusters for attitude correction are arranged around the side skirts of the propulsion cabin, saying that they are smaller than the main thrusters and much larger than other auxiliary thrusters. In addition, there is a small auxiliary propeller outside the propulsion cabin skirt.

Additional segment

The additional segment, also known as the transition segment, is used to prepare for future rendezvous and docking with another spacecraft or space station. Before manned flight and rendezvous and docking, he can also install various instruments for space exploration.

At this stage, there is no official introduction to the equipment of the additional section, but some people in the industry have made bold speculations. For example, one of the half-ring devices should be used to install square instruments. And three mutually perpendicular and extendable probes of 0.4m are considered as a part of navigation system or docking system. Because the Apollo spacecraft in the United States also has a similar device for docking. Russian docking system may be installed at the front end of shenzhou spaceship orbital module. However, these devices may only be experimental, and will definitely be replaced by new docking systems when docking with the space station in the future.

Shenzhou Spaceship

Shenzhou spaceship is a satellite spacecraft developed by China. The spacecraft consists of propulsion module, return module, orbital module and additional parts, with a total length of 8.86 meters and a total weight of 7790 kilograms. Shenzhou rocket was sent into low orbit by Long March 2F rocket.

structure

Propulsion module

The propulsion cabin of the spacecraft is located at the tail of the spacecraft, and its shape is cylindrical. It is equipped with four main engines and translation engines, and more than 20 square meters of main solar arrays are installed on both sides. The propulsion module is mainly used for attitude control, orbit change and braking of spacecraft.

re-entry module

The spacecraft's return capsule is located in the middle of the spacecraft, with a large blunt inverted cone, a diameter of 2.5 meters and a space of about 6 cubic meters, which can accommodate three astronauts. It is the spacecraft with the largest available space in the world at present. The shape of the spacecraft's return capsule is designed according to some lifting body, and the spacecraft adopts lift reentry mode. The spacecraft adopts the dome parachute recovery scheme, and the parachute area is1200m2, making it the largest parachute in the world.

Orbital module

The orbital module of the spacecraft is located at the front end of the spacecraft, which is cylindrical, with cone angles at both ends, and [solar cell] array, solar sensor, antenna and docking mechanism are installed at both sides. Orbital module is the living module, test module and cargo module of astronauts during their in-orbit flight. The orbital module has the ability to keep the orbit and can work continuously in orbit for more than half a year. The orbital module launched last time can rendezvous and dock with the next spacecraft, which saves the number of rendezvous and docking launches and reduces the overall cost of manned space program. The additional segment of the spacecraft is mainly used for the rendezvous and docking of the spacecraft, and it is generally decided whether the additional segment is needed according to the mission content.

About Shenzhou VI:

1, the weight of the spacecraft

The take-off weight of the rocket is 479 tons, the weight of the rocket and spacecraft is about 44 tons, and the rest is liquid propellant. So rockets are 90% liquid, which is greater than the water content of human body.

The spacecraft weighs more than 8 tons, accounting for 62% of the take-off weight of the ship-arrow combination: to put one kilogram of things into orbit, it will take 62 kilograms of rocket weight. Shenzhou VI spacecraft is heavier than Shenzhou V, so the rocket that launched Shenzhou VI is much heavier.

2. Track height

After the orbit was changed into a circular orbit, Shenzhou V and Shenzhou VI were all in the orbit with a height of 343 kilometers. The flight speed in orbit is 7.820185 km/s/s.

3, the temperature of the spacecraft

Fan Hanlin, chief designer of the thermal control subsystem of manned spaceflight project, said: During the flight of the spacecraft, the outdoor temperature on the sunny side exceeded 100 degrees Celsius, and the temperature on the back side was MINUS 100 degrees Celsius. The cabin temperature is automatically controlled at 17 to 25 degrees Celsius, and astronauts can also adjust it manually. The relative humidity is controlled between 30% and 70%.

When the spacecraft returns, the speed is very fast, and the temperature generated by friction with the atmosphere reaches above 1600 degrees, while the interior of the spacecraft should be kept above 20 degrees.

4. Why did the debris fall when the spacecraft was launched?

When the rocket lifted the spacecraft off the launch tower, some debris kept falling from the rocket body. Why is this?

Li Fuchang, deputy director of the Science and Technology Committee of China Academy of Launch Vehicle Technology, said that this is a measure for rocket insulation. In order to prevent the temperature of rocket propellant from being too high or too low, some thermal insulation foam materials were pasted on some parts of the rocket body. When the rocket was launched, it was fast and windy, and some foam materials fell, which had no effect on the success of the rocket launch.

5. Why was the command to orbit issued by Qingdao Railway Station?

Experts explained that the observation conditions, observation angles and equipment control conditions of TT&C station in Qingdao are the best among all TT&C stations in the process of separating the ship and the arrow and entering the orbit after ignition. Sending instructions to orbit in Qingdao can meet the receiving conditions of the spacecraft to the greatest extent. At the same time, Qingdao TT&C station is the last TT&C station in the ascent of Shenzhou VI. If we don't send orbit instructions here, we will delay the opportunity.

6. Why did you choose the launch angle of 42.4 degrees?

The ascent flight time of Shenzhou VI spacecraft was 583.828 seconds, and the spacecraft was sent into an elliptical orbit with a forward inclination of 42.4 degrees. Why choose 42.4 degrees?

Xi Zheng, director of Beijing Aerospace Control Center, said that you will find that our landing site is around 42.4 degrees. In this way, every time the spacecraft passes through 42.4 degrees, it passes through the landing site, so that the spacecraft has at least one chance to return every day. If the accuracy of the landing site is not very high, we may have two or three return flights every day.

7. Why did shenzhou spaceship change track?

When the Shenzhou VI spacecraft flew to the fifth lap, it changed from elliptical orbit to nearly circular orbit under the control of the ground command and control center. Why change the track?

According to Dr. Liu Yingchun, an expert in spacecraft orbit calculation, shenzhou spaceship separated from the rocket and entered the scheduled orbit at an altitude of about 250 kilometers. However, because the spacecraft still maintained a high flight speed at this time, it did not run in a circular orbit with a height of 250 kilometers, but in an elliptical orbit with a perigee of 350 kilometers to an apogee.

"The reason why the spacecraft has to change its orbit is mainly for autonomous emergency return." Liu Yingchun said. After the spacecraft turned into circular orbit, the trajectories of the first day, the third day and the fifth day were basically repeated. According to the design scheme, in this case, it is convenient for the spacecraft to return to the main landing site. At the same time, the autonomous emergency return scheme of circular orbit is more convenient to design than that of elliptical orbit.

8. Acceleration during the launch of Shenzhou VI.

It is said on TV that it is about 4 G, and it is 8 G when astronauts train.

Shenzhou-1: It was born.