At around 21:00 local time on April 27, the International Space Station welcomed four new passengers, namely American astronauts Kjell Lindgren, Bob Hines and Jessica Watkins, and European Space Agency astronaut Samantha Cristoforetti.
At this time, there were 3 Russian astronauts, 2 European astronauts and 6 American astronauts on the International Space Station. The number of people on the International Space Station reached 11.
However, this situation is short-lived, and the crew-3 mission's 3 American astronauts and 1 European astronaut will return to Earth in a few days.
In other words, the spacecraft docking with the International Space Station is a normal "handover shift".
At present, there are not many spacecraft that can transport astronauts to the space station, including Space X's Dragon spacecraft, Russia's Soyuz spacecraft, and the mainland's Shenzhou spacecraft.
Among them, the Soyuz and Continental Shenzhou spacecraft are both 3-cabin designs, which can pick up 3 astronauts at a time, while the Space X Dragon spacecraft is a 2-cabin design, including a crew module and a non-sealed cabin, which can pick up 4 astronauts at a time, up to 7 people.
So the question is, can the Dragon spacecraft with up to 7 people 2 cabin design more advanced? Why does the Mainland Shenzhou manned spacecraft adopt a 3-cabin design instead of a 2-cabin spacecraft?
Why does the Shenzhou manned spacecraft adopt a 3-cabin design?
In fact, when we developed a manned spacecraft, we debated whether the spacecraft was two or three. At that time, the experts provided a number of options, and finally identified 3 options:
Option one: Consists of an orbital module, a return module and a propulsion module
Scenario 2: Consists of a return module, an orbital module, and a propulsion module (the difference between the module and plan 1 is the distribution of the modules)
Option three: Consists of a return module and a propulsion module.
From the perspective of protecting astronauts, options two and three are more conducive to saving lives during the launch phase, because the return capsule is at the front, and when the launch fails, it only needs to be taken away by the escape vehicle.
However, both of these schemes have fatal shortcomings, and the two modules are designed for option 3 because there is no orbital module, which requires food, water, and the payload of the application system, scientific experimental instruments, etc. to be put into the return module.
In this way, it is necessary to design a return capsule with a large space, and the larger and heavier the return capsule, the higher the technical requirements for return, for example, the main umbrella design used today may not be able to meet the requirements.
Not only that, but it also affects the system that returns to the mission, as well as the system that can't stay on track to continue functioning.
Moreover, at that time, the 3-capsule design was more advanced, and although the mainland's aerospace industry had just developed at that time, the older generation of astronauts on the mainland believed that to do it was to do the most advanced.
After in-depth research, the mainland decided to develop a 3-capsule spacecraft and improved the first option, so that when the return capsule returns to Earth, the orbital module can still work in orbit and carry out various scientific experiments, which is the orbital module "orbit retention and reuse".
For example: Shenzhou V is the first manned launch mission on the mainland, the orbital module is also the astronaut's living capsule while carrying out scientific experiments, food, clothing and housing are inside, and finally it is also performed the function of cargo compartment, and after the astronaut returns to the earth, the garbage is left in the orbital module.
After the return of the re-entry module, the orbital module continued to work in orbit for about half a year, and during the orbital operation, various scientific experiments were still carried out before finally falling into the atmosphere.
The only Shenzhou spacecraft with track retention and reuse are Shenzhou 2, Shenzhou 3, Shenzhou 4, Shenzhou 5 and Shenzhou 6. After that, the orbital module of the Shenzhou spacecraft is no longer left in orbit for reuse, but it has other functions.
For example, Shenzhou 7 has the task of leaving the capsule, at this time, in addition to the above functions, half of the orbital module has also been changed to "airlock module", which is because the air pressure inside and outside the spacecraft is different, and there is no airlock cabin at all.
Since the beginning of Shenzhou 8, the mainland has basically aimed at the space station mission, that is to say, after Shenzhou 8, the spacecraft has a new task: rendezvous and docking.
The function of the orbital module has more cargo compartment + rendezvous and docking, it will carry about 300 kilograms of cargo, and there is a rendezvous and docking mechanism at the front of the orbital module to complete the rendezvous and docking of the spacecraft and the space station to form a combination.
That is to say, in the history of manned spaceflight on the mainland, the orbital module is actually a very flexible module, which has played different roles in different periods.
Why is the new generation of spacecraft a two-bay design?
Since the three-cabin design was the most advanced spacecraft at that time, why did the Dragon spaceship change to a two-cabin spacecraft?
This is actually different periods, the need for spacecraft is different.
At present, the new generation of manned spacecraft being developed internationally is basically a two-cabin design, including a new generation of manned spacecraft developed by the mainland.
(The Manned Dragon spacecraft already belongs to the active spacecraft)
Nowadays, the main function of manned spacecraft is to realize the function of round-trip between heaven and earth, more like a means of transportation, transporting astronauts to the space station to work, or taking people into space travel, at this time astronauts or passengers only need to stay in their seats, no need to go to the orbital module to work and live.
In addition, only the return capsule returns to the surface of the earth each time it returns, and the other two capsules will fall into the atmosphere and burn up, causing great waste. Moreover, the return capsule of the three-cabin structure is small, and many instruments and equipment and scientific experimental materials cannot be brought back.
That is to say, the advantages of the three-cabin structure in the past have now become shortcomings, while the shortcomings of the two-cabin structure have become advantages.
Nowadays, the return capsule space of the new generation of spacecraft is larger, and can accommodate more astronauts in space, such as: the manned dragon spacecraft can pick up 4 astronauts at a time, up to 7; the new generation of manned spacecraft on the mainland can also carry up to 7 astronauts, or 3 astronauts + cargo, making the manned spacecraft become a passenger and cargo spacecraft, with more diversified uses.
In addition, after the space of the return capsule becomes larger, the valuable and important instruments of the entire manned spacecraft can be installed in the return capsule. Unlike before, it was scattered before, with orbital modules and propulsion modules.
Coupled with the fact that countries are developing reusable technologies, when the return capsule returns to Earth for continuous use, it can greatly reduce the cost of manufacturing new spacecraft, reduce the transportation cost of travel between heaven and earth, and save more money for exploring other possibilities.
(Continental's new generation of manned spacecraft return capsule)
In addition, in the past, the development of the two cabins was restricted by the return capsule is too large, and the technical requirements for return are higher, but now this problem is no longer a problem, for example: the Shenzhou spacecraft uses 1 deceleration parachute, 1 main umbrella, and the new generation of manned spacecraft on the mainland uses a group umbrella, there are 2 deceleration parachutes, 3 main umbrellas, which can not only reduce the return capsule of ultra-high-speed flight to the speed of the car in the urban area in a very short period of time, but also ensure that in the future, when the astronauts return with the spaceship, the overload and attitude rotation feel good.
The landing airbag equipped at the bottom of the return capsule can not only adapt to the sea and land environment, but also achieve non-destructive landing, and realize the recyclability of the return capsule.
Of course, whether the three-cabin design is more advanced or the two-cabin design is more advanced, this is actually not comparable, because at different times, people need to solve different problems.
Whether it is a three-cabin design or a two-cabin design, it is to better serve the space exploration program, and we cannot break away from the general environment to judge which is more advanced.