Tiangong Space Station "Tianhe" core module is currently operating in a low-Earth orbit with a perigee of 352 kilometers, apogee of 385 kilometers, and an orbital inclination of 41.47°, which fully conforms to the established 340-450-kilometer near-circular low-Earth orbit, and an orbital inclination of 41-42 ° index requirements.
The Tianhe core module separated from the Long March 5B Yao-2 rocket
The first phase of the Tiangong space station project consists of the Tianhe core module, Wentian experimental module, and Mengtian experimental module to form the main body of the space station. The Shenzhou manned spacecraft will be added during the astronaut rotation period. The sky survey optical module will also dock with the space station when there is an on-orbit maintenance requirement. The maximum on-orbit mass of the Tiangong space station is close to 110 tons.
The Tiangong space station running in low-Earth orbit will suffer from orbital attenuation due to factors such as the earth's gravity and the high-altitude atmosphere. Therefore, the orbital power system needs to be lifted to maintain the orbital height. At the same time, the space station also has solar wing for sun pointing and space rendezvous and docking requirements Postural maneuvers are also required.
The largest configuration scale of the first phase of the Tiangong Space Station project is
tian and the core cabin is composed of three major structures: large column section, small column section and node cabin, with a launch mass of 22.5 tons.
The large column is divided into two parts: the pressurized airtight cabin and the resource cabin. The former is the main activity area for astronauts to work and live, and the latter is the attitude and orbit control power system of the entire space station.
Days and Core Modules The
resource cabin has a diameter of 4.2 meters and a height of 2.1 meters. It is shaped like a large drum and has a launch mass of 4.3 tons. Excluding the propellant , the structural weight is only 487 kilograms.
The core module and the large column section of the resource module
It is necessary to know that the resource module not only performs the attitude and orbit control tasks of the entire space station, but also supports the weight of the core module weighing more than 20 tons with a structural weight of less than half a ton during the ground test and launch phase. Especially in the launch phase, the rocket has to face the high overload and high vibration conditions of flight. For this reason, the loading weight of more than 350 tons was previewed in advance in the ground static test phase.
is different from the resource cabin layout of other spacecraft . The orbit control engine of Tianhe core cabin is not arranged at the bottom of the resource cabin, because there is a back-end channel for docking the Tianzhou cargo spacecraft. If the orbit control engine is connected to the docking channel The coplanar arrangement will adversely interfere with the docking mechanism, so it is arranged on the outer surface of the column of the resource cabin and installed in a sunken and inclined manner.
The largest diameter of the nozzle is the orbit control engine.
days and the core cabin are equipped with a total of 30 attitude and orbit control engines, of which 26 are attitude and orbit control power that consumes traditional propellants. All stages will play an important role. The core module has two docking ports that can be used for on-orbit propellant replenishment, and orbital lift can also be implemented by relying on the Tianzhou cargo spacecraft resource module. Among the
30 attitude and orbit control engines, 4 are the HET-80 Hall thruster developed by the Shanghai Institute of Space Propulsion. The maximum thrust of this type of thruster is 80mN and the rated power is 1.35kW.
The resource cabin is symmetrically arranged with four HET-80 Hall thrusters
The principle of the Hall thruster is that the inert gas collides with the high-speed rotating electrons to form a plasma, which is then ejected at a high speed to form a reaction force. This type of thruster mainly consumes electricity and a very small amount of inert gas, but the jet it forms cannot be underestimated, usually ten times that of a launch vehicle engine, so it has a very high specific impulse.
The Hall thruster is a type of electric propulsion. my country's electric propulsion industry is a typical example of a long-term accumulation. The first on-orbit application is nearly half a century later than other aerospace powers. However, due to solid accumulation, complete industrial chain and strong demand Stimulated by various factors such as , space electric propulsion equipment has formed a development trend in the past ten years, and has achieved parallel or even leading the world's strongest in many fields.
Practice-13 Satellites are equipped with LIPS-200 ion electric propulsion
Since 2012, practice-9A, practice-13, practice-17, practice-20 and other satellites have successively applied electric propulsion, two ion thrusters and Hall thrusters The parallel development of technical routes, supplemented by other types of electric propulsion technical routes, has formed a series of products such as LIPS, HET, LHT, etc. In particular, the successful ignition of the 20-kilowatt Hall thruster last year has pushed my country's electric propulsion cause to a whole new stage of development.
Practice-20 The LIPS-300 ion electric propulsion
Hall thruster configured with the satellite is the original application result of Tiangong Space Station's late development advantages. and of the International Space Station had a similar plan, but it has not yet been realized.
Why does the Tiangong Space Station use Hall thrusters, and what are its advantages?
1. Save the amount of traditional propellants, effectively reduce the frequency of Tianzhou cargo spacecraft, and improve the supply efficiency of various materials in the space station.
days and the core cabin HET-80 Hall electric thruster (physical)
propellant is a scarce consumable resource of the space station, a part of which is consumed will be less, and when it is used up, a Tianzhou cargo spacecraft will be launched for on-orbit replenishment. Just like the vertical recovery of the first stage of the Falcon 9 rocket of SpaceX, the goal of technological development is to serve engineering tasks more quickly, efficiently, and economically, not the other way around.
The Hall electric thruster can effectively compensate for the orbital attenuation under the influence of high-altitude atmospheric factors during operation, which brings a series of linkage advantages.
Tianzhou cargo spacecraft only needs to launch three times every two years.
2. Effectively reduce the size of the resource cabin and provide convenience for astronauts to work and live in orbit. With a launch mass of 22.5 tons, the Tianhe core module has become the largest single spacecraft launched by humans in the past ten years. Even so, it is still not proportional to the functions it undertakes.
Tianhe and core cabin
First of all, Tianhe is the main control module of the space station. It is not necessary to say much about the task of attitude and orbit control. It is also the main module for astronauts' work and life. It is equipped with three sleeping areas for astronauts to use independently. And functional areas such as hygiene area, dining area, exercise area, etc. In addition, 4 scientific research cabinets are also equipped, which is a capability that has not been achieved by any of the core modules of human space stations before, that is, the compatibility of the functions of the main control module and the functions of scientific research and experiments.
The internal view of Tianhe core cabin
This is not over yet. A large 10.2-meter-long main manipulator arm of the seven-degree-of-freedom space station is also equipped on the periphery of the small column section of Tianhe core cabin. There are also related control consoles in the cabin.
The multi-function Tianhe core cabin should be very crowded according to common sense, but in fact it has 50 cubic meters of activity space. Thanks to the late-moving advantages of technology, the miniaturized design and manufacturing capabilities of related components are obviously above the International Space Station. However, the application of HET-80 Hall electric thrusters is even more important, because such thrusters require working fluid is smaller in scale than traditional propellants.
HET series of Hall electric pusher products
3. Although the thrust of the Hall electric pusher is small, it has the advantages of long working time and more accurate orbit control.
The Tiangong space station has a design life of more than ten years, and can push the actual service life to fifteen or twenty years based on the on-orbit maintenance methods similar to the International Space Station. Although the application of Hall electric pusher has many advantages, it is It also faces many engineering problems. The most realistic problem is the lifespan and the addition of working fluids.
has made two preparations for our Hall electric pusher. First of all, it needs to be hard to strike the iron. The HET-80 Hall electric pusher has completed the long-life test task of accumulating 8241 hours in more than a year.
HET-80 Hall electric pusher ground operation test
days and the ratio of on-orbit repairable components in the core module is several orders of magnitude higher than that in the core module of the International Space Station, reaching 80% of the repairable ratio, and the maintenance convenience is also higher. The
HET-80 Hall thruster is no exception. Zooming in on the photo of the Tianhe resource cabin, you can see that there are handle devices on both sides of the thruster, which is a special design for astronauts' on-orbit maintenance.
HET-80 Hall electric pusher is equipped with a handle that is easy to disassemble.
So, how to supplement the working fluid of electric pusher? Although the Tianzhou cargo spacecraft has the function of on-orbit propellant replenishment, it is for the replenishment of traditional propellants and does not have the replenishment function of Hall electric propulsion working fluid. For this purpose, a Hall electric propulsion engine gas cylinder that can be replaced by astronauts is specially designed, which solves the problem of on-orbit replenishment of electric propulsion working fluid.
In addition to the traditional attitude and orbit control power and the Hall electric pusher, the Tiangong space station also has the attitude maneuvering ability under the condition of zero propellant consumption, which is due to the border between the large column section and the small column section of the Tianhe core module. 6 control moments gyro .
Controlling moment gyro
The Tiangong space station is equipped with 23 scientific research cabinets on the 100-ton body, compared with 31 scientific research cabinets on the 400-ton International Space Station. The former uses a quarter of the latter's volume in terms of scientific research capabilities. The is equal to , and the external loads such as the large space manipulator and the experimental cabin manipulator are also available.
In addition, Tiangong Space Station also has the ability to expand tasks. It is planned to launch another core module and two experimental modules. The maximum size of the space station can reach 180 tons. By then, the number of scientific research cabinets will be doubled, and the comprehensive scientific research capacity will be compared. On the International Space Station, it will change from an equal view to a comprehensive overtake.
This puts forward higher requirements for the power supply capability of the space station. Why? Because scientific research cabinets are large consumers of electricity.
Day and core module flexible solar wings
For this Tiangong Space Station, three-junction flexible gallium arsenide solar cell wings with international advanced level have been applied. The photoelectric conversion efficiency is over 30%. A pair of core pod battery wings will also be added to the mission.
Tiangong Space Station 70% of the power generation tasks will be undertaken by a single flexible three-junction gallium arsenide battery wing with an unfolded area of 100 square meters arranged on the short truss at the end of the two experimental cabins Wentian and Mengtian. This type of battery wing itself has two freedoms In order to achieve the ability to point to the sun, the space station also needs to adjust the attitude in time to serve the pointing to the sun during the operation. If such normalized attitude maneuvering tasks against the sun all rely on the attitude control engine, the operating cost will increase, and the large control torque gyroscope will play a role at this time.
The large-scale flexible solar wing has the requirement of pointing to the sun.
The control torque gyro does not consume propellant and only consumes electricity, and electricity is a renewable energy source for Tiangong Space Station. The torque controls the attitude maneuver of the spacecraft, which is more stable and precise than the traditional attitude control power control. The control torque gyroscope can be repaired and replaced on-orbit like the Hall electric pusher.
Long March 5B Remote 2 rocket launch Tianhe core module
Reminiscent of the old salute series of space stations over the earth, Skylab, Mir Space Station, Space Shuttle, Union manned spaceship... You sing and he will appear, and we It is just an audience. The Tiangong space station under construction now not only heralds the replacement of the protagonist of the space stage, but also opens a new chapter in the history of human manned spaceflight with the Tianhe core module, which means peace in the world. Future-oriented main force.
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