The Transformation of the Shenzhou Orbital Module

The Shenzhou spacecraft is the only manned spacecraft currently in service in my country. As we all know, the Shenzhou manned spacecraft has a three-cabin structure, consisting of an orbital cabin, a return cabin, and a propulsion cabin. This has been the case since Shenzhou 1. So we inevitably have an illusion that Shenzhou 1 to Shenzhou 13 are all the same. In fact, this is not the case, especially the orbital cabin, which has played many roles and has undergone earth-shaking changes.

For a long time, the functions of the spacecraft's return capsule and propulsion capsule have been relatively fixed: the return capsule is the astronauts' cockpit during the ascent and return phases, and most of the spacecraft's key status information is displayed on the instrument screen of the return capsule. During the years when the spacecraft flew solo, the astronauts had to take turns on duty in the return capsule almost all the time to ensure that they could grasp the spacecraft's flight status at all times. Therefore, the role of the return capsule is the astronauts' cockpit + work cabin; the propulsion capsule, as the name implies, provides propulsion power for the spacecraft, and the engine, power supply, etc. are all located in the propulsion capsule. Therefore, the role of the propulsion capsule is the spacecraft's energy cabin + power cabin.

The role of the orbital module is more complex. It has undergone many transformations since Shenzhou 1, which can be roughly divided into the following five stages.

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Stage 1: Counterweight Chamber

The Shenzhou-1 orbital module has no other equipment installed except the power supply equipment for orbital separation and return. It only serves as a counterweight and flies in orbit for one day.

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Phase II: Space Science Experiment/Technology Test Chamber

Starting from Shenzhou II, the orbital module was given the function of a space science experiment/technology test module. From Shenzhou II to Shenzhou VI, after the return module returned to the ground, the orbital module continued to fly in orbit as a stay-on-orbit module. This is also the reason why the orbital module of early spacecrafts has solar panels to provide power for equipment during independent flight after the orbital module is separated.

The orbital module that remained in orbit flew in orbit for about six months. The orbital module and the additional section at its front end were equipped with corresponding payload equipment according to different experimental/testing requirements, and carried out research in multiple fields, such as space astronomy, earth observation, scientific experiments in space physics/life/biology/materials, comprehensive monitoring of space environment, verification of new aerospace technologies, etc. A number of scientific and applied results with international leading level were obtained, which comprehensively improved the level of space science research and aerospace technology development in my country.

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Phase 3: Living cabin + work cabin + cargo cabin

From Shenzhou V, the spacecraft began to carry out manned missions. Yang Liwei did not enter the orbital module during his first flight because of the short time. So strictly speaking, from the Shenzhou VI mission, the orbital module, on the basis of conducting scientific experiments/technical experiments, also added the function of the astronauts' living cabin. The cabin is equipped with food heating devices, urine and feces collection devices, sleeping bags and other facilities. It is a place for astronauts to eat, wash, go to the toilet and sleep. At the same time, the orbital module is also the astronauts' work cabin. my country carried out manned space science experiments for the first time in Shenzhou VI, making my country the third country in the world that can carry out manned space science experiments.

In addition, the orbital module is also used as a cargo compartment to transport spare parts and supplies needed for the normal operation of the spacecraft, as well as the living and working materials of the astronauts. After the spacecraft completes its mission, the garbage generated by the astronauts in orbit and items that do not need to be returned to the ground will be stored in the orbital module as garbage, and will burn up in the atmosphere with the cabin after the orbital module leaves orbit.

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Stage 4: Airlock

In order to complete the extravehicular mission of Shenzhou VII, the orbital module was temporarily requisitioned as the airlock on the basis of the above functions, and the entry hatch in the orbital module through which astronauts entered the spacecraft before launch also became the in-orbit egress hatch.

The airlock is similar to the ship lock of the Yangtze River Dam. The difference is that the ship lock is used to transition the water level, while the airlock is used to transition the gas pressure from normal pressure to vacuum. Foreign manned spacecraft have special airlocks.

Converting the astronauts' dual-purpose living cabin into an airlock cabin is an original move in my country's aerospace industry.

In addition, a companion satellite was installed at the front end of the Shenzhou VII module, which was released after the spacecraft entered orbit. The companion satellite took a clear picture of the entire spacecraft, which was the first time that my country took a real picture of a spacecraft in orbit.

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Phase 5: Rendezvous and docking mechanism boarding

Starting from Shenzhou 8, China's manned space program has entered the era of space laboratory/space station. The space science experiment function of the spacecraft has been gradually replaced by the Tiangong Space Laboratory and the current Tiangong Space Station. The role of the orbital module as a "space science experiment/technology test module" has been downplayed and turned into supporting the completion of rendezvous and docking, allowing astronauts to smoothly enter the space laboratory/space station. In other words, for the spacecraft orbital module, it has entered the era of rendezvous and docking.

The additional section on the top of the orbital module was removed and replaced with a docking mechanism and the front hatch of the orbital module. After the spacecraft and the space laboratory/space station completed docking and formed a combination, the astronauts passed through the front door of the orbital module and entered the larger space of the space laboratory/space station to work and live. After that, the orbital module also removed the role of "living module + working module" until the spacecraft completed its mission and separated from the space laboratory/space station.

After Shenzhou 8, the status of the spacecraft's orbital module was basically fixed and has been in use to this day.

Source: China Digital Science and Technology Museum