Starting as a "temporary worker", how did Airlock transform into a "business elite"?

Currently, Chinese astronauts are using the Wentian Experimental Module airlock to conduct spacewalks. Did you know? In the past, Chinese astronauts have used temporary airlocks converted from the Tianhe core module node module and the Shenzhou spacecraft orbital module to conduct spacewalks, gaining a lot of experience. The dedicated airlock has different locations and conditions for spacewalks compared to other options, and has unique advantages. Looking to the future, I believe that there will be more complete and efficient new options for astronauts to exit the spacecraft.

Chen Dong and Liu Yang took a group photo outside the cabin

The starting point of "Jijiu Zhang" modification is high

When talking about space extravehicular activities, we cannot fail to mention the first spacewalk by a Chinese.

In 2008, the astronauts of the Shenzhou VII spacecraft carried out the first Chinese person's space extravehicular activity. Zhai Zhigang's words "I have been out of the cabin and I feel good" left a deep impression on everyone.

Zhai Zhigang exits the Shenzhou VII spacecraft

At that time, the airlock of the Shenzhou VII spacecraft was designed by making full use of the existing technological basis and improving the orbital module. It was both an innovation and a temporary measure taken by Chinese aerospace researchers to master extravehicular activity technology. Since then, the Shenzhou spacecraft has never used this method again.

Don't underestimate this hastily modified temporary airlock. It helped my country break through the key technology of airlocks, making my country the third country to independently master space exit technology. It can be said that the technical starting point is quite high.

According to public information, the airlock of Shenzhou VII spacecraft directly utilized the basic structure of the original orbital module, and through systematic redesign, the airlock function was added. The airlock has two core functions: one is the sealing ability; the other is the pressure relief/recompression function. Sealing is the inherent ability of the orbital module, and in order to support astronauts' extravehicular activities, this section is specially equipped with a pressure relief device composed of pipeline valves and a recompression device supported by 5 high-pressure gas cylinders to meet the gas demand for two pressure relief/recompression. It also provides a series of functions such as storage, transportation, supply of extravehicular space suits, extravehicular activities, photography, lighting, etc.

However, the conversion of the orbital module of the Shenzhou VII spacecraft into an airlock was only a stopgap measure, and there were inevitably some flaws in the details, as can be seen from the embarrassment of Zhai Zhigang's failure to open the hatch when he left the cabin. Analysis found that there were a lot of living and working supplies stored in the orbital module at the time. After the airlock was depressurized, these supplies and equipment were still exhausting, resulting in the depressurization progress being slower than expected. After Zhai Zhigang opened the hatch a little, it was "pushed" back by the air pressure inside the cabin.

Even so, the airlock of Shenzhou VII is still much more advanced than the similar ones of the United States and the Soviet Union in the early days. The first human spacewalk was carried out by Soviet astronaut Leonov from the Voskhod 2 spacecraft in 1965. At that time, the spacecraft carried the "Volga" flexible inflatable airlock, which could only support one astronaut to leave the spacecraft.

As for the American astronauts' initial space exit, it was even more of a "hasty job" - the Gemini spacecraft was only slightly larger than the Mercury spacecraft that was "worn on the body", and the entire return capsule was depressurized and emptied without any mission redundancy and without any accidents. We can only say that the Americans were very lucky.

Both "part-time" and "dedicated" are very strong

As the construction of China's space station progresses, astronauts have carried out multiple missions from the Tianhe core module. During this process, the Tianhe core module used the node module as an airlock, drawing on the experience of the Shenzhou VII spacecraft's modified airlock, and the design was more perfect.

According to publicly released videos and pictures, the hatch lock of the Tianhe core module node module exit hatch is set on the side, and an assist handle is added so that the hatch can be opened smoothly.

In addition, this "part-time" airlock used gas reuse technology for the first time in China's manned spaceflight history, making China the second country to master this technology after the United States. With the help of equipment such as the inter-cabin air pump, the Tianhe core module can partially recycle and reuse the gas in the node cabin, significantly reducing the oxygen consumption of extravehicular activities, which is of great significance for saving resources and transportation capacity, improving astronauts' long-term on-orbit capabilities, and supporting multiple extravehicular activities.

The crew of Shenzhou 13 spacecraft exits the Tianhe core module node module

In contrast, Russia, a veteran power in manned space flight, has independently operated the Salyut series and Mir space stations, and has also participated in the construction of a large number of modules on the International Space Station. However, the airlock has always used a direct pressure relief exhaust device, and the gas is directly discharged into a vacuum, which may cause gas pollution or interfere with the spacecraft's attitude. The air discharged from multiple extravehicular activities is also a considerable consumption.

It can be said that China's space station has the latecomer advantage in this regard and is one step ahead in technology.

The "part-time" airlock of the Tianhe core module is also a transitional facility. In the future, Chinese space station astronauts will mainly use the dedicated airlock of the Wentian laboratory module to go out of the cabin. As a specially designed and independently used airlock, its length and diameter are longer than the orbital module of the Shenzhou spacecraft, its internal volume is larger, and it also uses gas reuse technology. During the preparation stage for going out of the cabin, astronauts will pump the air in the airlock to the adjacent sealed cabin to minimize the consumption of air resources.

The volume of the airlock cabin of the Wentian experimental module is 50% larger than that of the node cabin of the Tianhe core module. The cabin door is more spacious, with a diameter of 1 meter. Astronauts can wear thick extravehicular spacesuits without being restricted in turning around and moving, and can carry equipment more easily.

Astronauts Jing Haipeng and Zhu Yangzhu in the airlock of the Wentian laboratory module

The door used for exiting the cabin is a complex aerospace product, covering the disciplines of sealing, transmission, locking, ergonomics, etc. The astronauts' operating force remains unchanged. They only need to rotate the matching handle to unlock it, use the power-assist mechanism to eliminate the residual pressure, and pull the door handle to open it. When the cabin door is closed at ordinary times, the matching leak detector and other equipment can ensure safety in all aspects.

Chen Dong opened the airlock hatch of the Wentian experimental cabin to exit the cabin

Of course, some people may worry: this exit is located directly below the airlock, and the astronauts are equivalent to exiting the cabin upside down. Will it be dangerous? In fact, the gravity in low-Earth orbit is very small, so even if the astronauts "hold their heads up" to exit the cabin, it will not be a big problem.

Look at the airlock of the Wentian experiment module from a different angle

The Chinese space station will travel in space for many years. Will Chinese astronauts use more advanced airlocks in the future? There is currently a new concept of a two-chamber hybrid inflatable airlock. Specifically, the use of an inflatable compartment as a crew airlock not only reduces the volume and mass of the airlock, but also maintains the inherent advantages of a double-chamber airlock, and can more conveniently and efficiently reuse gas and reduce gas consumption. In addition, the new design has a stronger impact resistance and can better protect the astronauts inside from threats such as micrometeoroids and orbital debris. In short, the airlock will inevitably continue to improve, so let us wait and see.