Source: China Aerospace News
As we all know, as of now, the astronaut outgoing activities in the stage of China's space station have been carried out twice and have been a complete success. Astronaut out of the capsule activities and manned space round-trip, rendezvous and docking together, known as one of the three basic technologies of manned spaceflight, has a unique and important role in the development of manned spaceflight, especially in the formation of space stations, space maintenance and repairs and space rescue and other tasks play a huge role. Let's take a closer look at this dangerous and romantic task.
China's space station stage astronauts for the first time out of the capsule
· Space Environment Breakthrough Four Levels ·
Astronaut out-of-space activities are also called spacewalks. Out-of-the-shell activity is a general term for a series of processes in which astronauts leave a manned spacecraft or a base built on other celestial bodies, rely on their own life support systems, work and activities in space or on the surface of other celestial bodies, and then return to a manned spacecraft or base. Manned spacecraft here include spacecraft, space shuttles, space stations and lunar modules.
The spacewalk is one of the most dangerous missions in spaceflight. The astronauts left the protection of the spacecraft and entered the vast space alone, floating in orbit at a speed of nearly 8 kilometers per second, while facing the harsh space environment of vacuum, strong radiation, weightlessness and alternating sudden cold and heat.
First of all, in the vacuum environment, if the astronaut loses effective protection, he will lose consciousness due to lack of oxygen within 15 seconds and die within 30 seconds. Without atmospheric pressure, human blood and body fluids "boil" like boiling water, while skin, tissues and organs expand outward.
Second, space does not have a barrier to Earth's atmosphere and magnetic field, and astronauts will be directly exposed to a variety of cosmic radiation, including solar rays ejected during solar flare eruptions, high-energy particles in the Milky Way, and non-ionizing radiation such as ultraviolet, infrared, and radiofrequency radiation. These radiations can cause varying degrees of harm to the human body, and if the safety limit is exceeded, it will cause astronauts to suffer from radiation sickness and even endanger their lives.
Third, in the space weightless environment, astronauts will have vestibular dysfunction, resulting in dizziness, nausea, vomiting and other "space sports diseases". Long-term weightlessness will cause increased excretion of inorganic salts such as calcium, phosphorus and magnesium in the human body, and osteoporosis and muscle atrophy will occur.
In addition, there is no air in space, convection disappears, and the temperature changes are very drastic. The space station orbits the earth for 90 minutes, half the time by the sun, half the time by the earth, the temperature exceeds 100 degrees Celsius when irradiated, and drops to minus 100 degrees Celsius during the barrier. In this extreme environment of alternating hot and cold, astronauts last for several hours to walk spacewalks, which is a great test of body and mind.
Astronauts need to face the four levels of the space environment, and the extravehicular spacesuit is the ultimate guarantee for the test.
Chinese extravehicular spacesuit
The extravehicular spacesuit consists of clothing, helmets, gloves and space boots, the most complex of which is the clothing, which has 6 layers from the inside to the outside. The innermost layer is the lining and urine collection device; followed by the liquid-cooled ventilation layer for heat dissipation; the third and fourth layers are the pressurized airtight layer that maintains the pressure inside the spacesuit and the restriction layer that restricts the outward expansion of the pressurized airtight layer; the fifth layer is the thermal insulation layer to cope with the extreme temperature difference changes outside the cabin; the outermost layer is the protective layer, made of a variety of fiber composite fabrics, with good softness, penetration resistance, wear resistance, high temperature resistance, combustion resistance, corrosion resistance, radiation resistance, and other mounting interfaces.
In addition, the extravehicular spacesuit also provides an independent backpack-type life support system, a gas-hydraulic-electric support system, measurement and control and communication devices, which can be said to be the most miniature spacecraft.
· Spacewalk Preparations ·
Before the spacewalk, the astronauts' preparations for the capsule are also very complicated. They need to operate hundreds of devices, which puts forward high requirements for professional knowledge and operational skills. Astronauts should be clear about the shape, location, operation method, operation essentials and associated actions of any equipment, and they must prepare for many days before leaving the capsule, and they must prepare for several hours in advance on the day of leaving the capsule.
Chinese astronauts inspect extravehicular spacesuits
Astronauts first wear extravehicular clothing, to carry out the system inspection of extravehicular clothing and the onboard docking system inspection of extravehicular clothing, "drill" into the clothing, and adjust the size of the clothing, airtightness inspection and full performance test to ensure that everything is normal. During the "dressing" process, two astronauts cooperate with each other, one person operates, and the other reads the operation manual to confirm, ensuring that all steps are foolproof.
The second step is to conduct on-orbit training. After putting on the extravehicular suit, the astronauts have to carry out movement and various simulated operations to experience the characteristics of movement and operation in the weightless state. Although there are neutral buoyancy tanks on the ground to provide weightlessness training, there is still a big gap compared to the real space environment.
At the same time, astronauts should find the location of the opening door and the focus of their hands and feet. In the process of orbit training, astronauts should rehearse the entire in-orbit preparation and extravehicular activities to further familiarize themselves with the outgoing procedures, but the amount of movement should not be too large to prevent suffering from space movement diseases. After these jobs are completed, the astronauts will take a break for a while.
Finally, there is the gatekeeping procedure and opening the door. Astronauts enter and exit the space station through the airlock module. After the astronaut enters the airlock module, the inner hatch is closed, the outer cabin is pressurized, and the oxygen inhalation and nitrogen emission are carried out at the same time to avoid decompression sickness.
Preparation before leaving the cabin
The airlock chamber slowly deflates the pressure, and when it is discharged to 3 kPa, the cabin jacket is disconnected from the spacecraft's gas-liquid combination connector, and the clothing is transferred to fully autonomous oxygen supply and cooling.
When the air pressure drops to about 1 kPa, the outer hatch can be opened. Unlock the door when you open the door, wait until the pressure inside and outside the cabin is balanced, and then open the door completely. Before leaving the cabin, the astronauts also have to put a protective cover on the door to avoid rubbing in and out of the cabin. In this process, the astronaut always has to fix the body with one hand, and only relies on one hand to complete all the movements.
After several hours of preparation, the astronauts can officially carry out extravehicular activities.
· Heaven and Earth with Spacewalk ·
Astronauts going out of the capsule for spacewalks will be governed by the laws of physics, which is extremely dangerous work, and if they are not careful, they will be launched into space by the space station, and they need to follow a set of action and technical specifications.
According to the calculations of domestic and foreign experts and the experience of the International Space Station, astronauts will maintain several different relative trajectories with the space station after leaving the capsule (related to the exit point), and the astronauts' orbits are usually elliptical. The force and angle used by the astronaut when leaving the capsule will affect his orbit during the "space flight", and the slight deviation of the force and angle will fall into space, so the astronaut must have a wealth of physical knowledge and thousands of times of training to carry out spacewalks.
Chinese astronauts conduct extravehicular operations
When operating outside the cabin, astronauts should tie a safety rope. In order to facilitate the movement of astronauts, the space station is specially installed with handrails outside the cabin, and astronauts can move their bodies like climbing, which requires good arm strength and physical strength. During the first space exit capsule walk of China's space station stage astronauts, one relied on the space station's extravehicular armrest to move through the traditional way, and the other assisted the movement through the mechanical arm. At the same time, the sub-systems of the ground measurement and control center cooperate closely to establish communication connections through the skylink series of satellites, providing high-speed voice image relay services for real-time observation of astronauts' out-of-the-cabin status and dialogue and communication between astronauts and the ground.
Under the close cooperation between space and earth and inside and outside the capsule, the two astronauts completed the installation of foot limiters and extravehicular workbench on the robotic arm, cooperated with each other to carry out the assembly of relevant equipment outside the space station, and coordinated the lifting operation of the space station's extravehicular panoramic camera.
In the second outgoing activity of the space station stage, the two astronauts have completed the tasks of installing the extravehicular expansion pump group and lifting the panoramic camera D, and the whole process has been smoothly and successfully completed, which further tested the functional performance of China's new generation of extravehicular spacesuits, tested the ability of astronauts to work together with the robotic arm and the reliability and safety of the support equipment related to the outgoing activities.
The astronauts of the Space Station stage of our country went out of the capsule for the second time
In order to ensure the safety of astronauts' spacewalks, the best time should be chosen for the outgoing activities, which is the exit window.
The time to choose to consider the safety of people and equipment safety, as far as possible arranged in the sunshine area. When the space station is in low Earth orbit, it has repeatedly crossed the Anomalous Zone of the South Atlantic, and the abnormal radiation in this area has an impact on electronic equipment and instruments, and it is also harmful to the human body, so the arrangement of outgoing activities must avoid this area.
Text/Yang Shirui