The Shenzhou-19 spacecraft has been in orbit for nearly six months, the Shenzhou-20 spacecraft has been launched, and the two astronaut crews have completed the handover. According to the original plan, the Shenzhou-19 spacecraft returned on April 29, but the return of the Shenzhou-19 spacecraft was postponed. What's going on?
Shenzhou-19 postponed its return
Seeing the postponement of the return of the Shenzhou 19 spacecraft, some netizens may think of the two astronauts who were trapped on the International Space Station for more than 9 months in the United States, but there is no similarity between the two. The postponement of the return time of the American astronauts is due to the problem of the spacecraft, while the postponement of the return of the Shenzhou-19 spacecraft is an external problem caused by the weather at the landing site.
On June 5, 2024, American astronauts Wilmore and Williams took the "Starliner" spacecraft developed by Boeing to the International Space Station.
In order not to affect the follow-up manned mission, the United States allowed the problematic "Starliner" spacecraft to return to its home "empty ship," and the two American astronauts were stranded on the International Space Station waiting for the Dragon spacecraft to pick them up. As a result, the two of them stayed for more than 9 months.
The return time of the Shenzhou 19 spacecraft was originally scheduled for April 29, so the Shenzhou 20 spacecraft was launched a few days early, and the two astronaut crews had enough time to complete the handover. After completing the handover task, the Shenzhou-19 spacecraft can return, but due to the recent meteorological conditions at the Dongfeng landing site that do not meet the requirements of the mission, for the safety of the astronauts, it was decided to postpone the return of the Shenzhou-19 spacecraft. This has no impact on our space station, the astronauts are safe, the spacecraft is operating normally, and you don't need to worry.
When the Tianzhou-8 cargo spacecraft was launched, the materials in the space station were enough for 3 astronauts to use for about 1 year, so now the space station will not face a shortage of materials because of the postponement of the return of the Shenzhou-19 spacecraft. Moreover, the return time of the Shenzhou-19 spacecraft is only slightly delayed, not a large delay, and it will return when the weather conditions at the landing site meet the requirements.
Why does the weather affect the return home?
Some netizens may be curious, why can't the spacecraft return when the weather conditions at the landing site do not meet the requirements?
In fact, as long as the weather conditions are not very bad, it is possible to return, but for safety reasons, it was postponed.
Because the process of returning to the spacecraft is very complicated, no mistake can be made in any link, and if there is a little mistake, it may lead to an accident. Therefore, the launch, return, and in-orbit flight of the spacecraft will only be carried out when full preparations are made. In processes such as rocket launch and spacecraft return, if any problems are found, the launch will generally be postponed or the return will be postponed.
Because the spacecraft is still very fast after re-entering the atmosphere, it needs to be parachuteed. The Shenzhou manned spacecraft has three umbrellas: a guide parachute, a parachute, and a main parachute, which are opened successively to slow down. The main umbrella has an area of 1,200 square meters, which is very large, and can cover three basketball courts when fully deployed. With the help of these parachutes, the descent speed of the return capsule of the Shenzhou manned spacecraft can be reduced to about 8 meters per second.
And this parachute process needs to take into account the weather conditions. Because such a large main parachute hangs the spacecraft return capsule to slow down, if the wind speed is relatively strong, it may blow away the return capsule and fly far away from the pre-selected landing site, which will increase the difficulty of ground search and rescue.
Moreover, we generally choose the landing site of the spacecraft in a relatively flat area, with a wide view of the surrounding area, and there are no buildings, pits or high ground. And if the ship's return capsule is blown away during the parachute, we may not be able to control where it lands. If you land on flat ground, fine, if you land on uneven ground, the ship may roll over or cause other problems, and if you land in a populated area, it may also cause some impact on people on the ground.
When the spacecraft has landed safely, if the crosswind is strong, it may be dragged away by a parachute, causing the spacecraft to roll on the ground. This is also a problem for astronauts. Because they had only finished their six-month flight mission at this time, they had been in a state of weightlessness for a long time, and when they returned to the ground, they had not yet adapted to the gravitational environment on the ground, and their bodies might be injured due to the rolling of the spacecraft.
In addition, the weather conditions at the landing site will also affect the search and rescue work on the ground. Even if the spacecraft's return capsule accurately lands at the pre-selected landing site, the search and rescue work will be affected. Because the landing site is located in a desert or desert area, bad weather may raise sand and dust that obscures the sky, which is not conducive to the development of search and rescue work.
In fact, it is not uncommon for spacecraft to be delayed due to weather conditions at the landing site. Previously, the U.S. Crew Dragon spacecraft had also postponed its return due to the weather in the sea area where it landed. So you don't need to worry too much, because the weather at the landing site is normal for the situation in front of you, as long as there is no problem with the spacecraft, wait for the weather to improve, and the spacecraft will return.
Why are astronauts carried out of the capsule?
Now the Shenzhou 19 spacecraft has been postponed due to weather, but it is clear that when the spacecraft lands safely, these astronauts will be carried out of the capsule and carried away, just like the previous manned missions. The same is true of foreign astronauts returning to Earth from the ISS on the Crew Dragon spacecraft and the Soyuz manned spacecraft, without exception. What's going on?
In fact, this is also a normal situation, and you don't need to worry. Because astronauts perform long-term missions in the space station, their bodies have adapted to the weightless environment of outer space, their bodies no longer need to fight the gravity of the ground, muscles and bones will be lost faster, and some body functions will also be affected, the American astronaut Williams, who has been trapped on the International Space Station for more than 9 months, once said that she has forgotten the feeling of walking.
When they return to the ground, their bodies have not fully adapted to the gravity of the ground, and there needs to be a transition period, and if they are allowed to stand and walk directly, they may fall and even break bones. Therefore, for the safety of the astronauts, after leaving the capsule, the ground staff will carry them and let them sit on chairs to rest.