How accurate is the landing point of Shenzhou 13?
The accuracy of the actual landing point and the forecast landing point is only 130 meters apart, which is equivalent to the result of hitting ten rings in wanli.
It should be known that Shenzhou 13 landed from an orbit 400 kilometers away from the earth, and after 5 turns around the earth, it can still make an accurate landing, which can be said to be very difficult.
So how did the continent complete such a difficult and accurate landing? Who is better than the space powerhouse, the United States?
How does Shenzhou 13 achieve accurate landing?
The Shenzhou 13 return to Earth this time, using fast return technology, how fast is this technology?
Shenzhou XII spacecraft and Shenzhou XIII, the same from the mainland space station return, the landing field is also the East Wind landing field, it is reasonable to say that the two return time should be the same, but in fact, shenzhou XII spacecraft spent 28.5 hours, and Shenzhou XIII spacecraft only took 9 hours.
Fast, not because we have accelerated, but because our return technology is more accurate.
When the spacecraft returns, it is not along a straight line distance, but the spacecraft and the earth are rotating, at this time to land to the predetermined landing site, you need to find the return window, if you do not land at the return window, it is likely to deviate from the scheduled landing site, and it is also possible to land in other countries, bringing unnecessary trouble.
For example, when the Gemini 8 spacecraft returned, it was supposed to return to the atmosphere after 3 days, but because of the problem with the spacecraft, astronaut Armstrong and another astronaut did not insist on 3 days at all, and could only return as soon as possible. As a result, it landed on the surface of the sea 800 kilometers east of Okinawa, half a world away from the original landing site.
Moreover, there is no search and rescue team here, although the two astronauts landed safely on the earth, but waited for a long time, before a plane found them, because the plane could not take them out of the ocean, 2 astronauts waited in the ocean for more than 3 hours before waiting for the ship.
In fact, this is still a good thing, if the two landed at Nemo Point in the South Pacific, they may have been killed before they could come to the rescue.
Finding the return window does not mean that it can be returned, the spacecraft return capsule also needs to adjust the attitude, only to ensure that the large head of the return capsule rushes downwards, in order to better insulate and protect the life safety of astronauts.
If the return capsule is not adjusted when running to the return window position, it is necessary to continue to run until both are satisfied, at which point the brake can be braked and slowed down.
You might think, "Isn't it just about slowing down, similar to stepping on the brakes, who wouldn't?" ”
The fact is really not so simple, the brake deceleration requirements are not fast or slow just right, if the "braking" time is a few seconds more, or a few seconds faster, it will deviate from the predetermined landing point.
In the last century, the former Soviet Union's Ascendant spacecraft encountered problems when it descended, resulting in the need for astronauts to manually operate the machine, but because of the design reasons, the operating platform was at a 90° angle with the astronauts, plus two astronauts wearing bulky spacesuits, the operation was very troublesome, resulting in tens of seconds more.
Supposedly it would only be a few tens of seconds, and nothing would happen, but it caused the spacecraft to deviate 380 kilometers from its scheduled landing site, and the two astronauts landed in the dense primeval forest.
The environment in the forest is very harsh and very unfavorable to search and rescue, it is difficult for vehicles and personnel to enter, and aircraft cannot be docked. What's more, it was still very cold at this time, and they didn't have warm clothes yet.
There are also many bears and tigers living in the forest, and later because of this lesson, the former Soviet Union, Russia and continental astronauts all wore specific pistols to enter the space station, so that the landing of the return capsule was not accurate, and when they encountered wild beasts, astronauts could also deal with them.
Because of the deviation from the scheduled landing site, the search and rescue team was not nearby, resulting in two astronauts being frozen in the ice and snow for a night before waiting for the rescue team, and when they actually left, it was already the third day.
Therefore, the rapid return technology of the Shenzhou 13 spacecraft can not only ensure that the spacecraft adjusts its position, but also can make emergency braking when it reaches the return window, and the speed of braking is just right, in order to accurately land on the Dongfeng landing field, which is very difficult.
In the past, the return capsule had to circle the earth for about 11 times to adjust the position and find the return window, while Shenzhou 13 only needed about 5 laps to do it, the number of circles around the earth was less, and the time to go home was shortened from the original 28 hours to 9 hours, allowing the astronauts to get home quickly.
The rapid return technology also shows that the mainland's technology in terms of return is more mature.
After the spacecraft slows down and falls into the atmosphere, the satellites on standby at this time, radar, etc. will begin to look for their figures, because after the spacecraft enters the atmosphere, because of the fast speed and high air density, the return capsule will have a fierce friction with the air, resulting in the temperature of the bottom of the return capsule reaching thousands of degrees Celsius, which will cause the return capsule to be surrounded by flames, and at the same time isolate the connection between the spacecraft and the outside, which is also known as the "black barrier area".
Although the return capsule in the black barrier area will lose contact with the ground staff, we can still use other means to track the return capsule.
When the return capsule is at an altitude of about 10 kilometers from the earth, it will open the guide parachute, deceleration parachute and main parachute.
The staff will forecast the landing point location according to the position of the return capsule, braking conditions, wind conditions, etc., and forecast 2-3 times, each time more accurate than the first.
According to the expected landing location, the ground search and rescue team will go to the local area to assemble, but the time of appearance cannot be too early, this is to prevent the return module shedding debris hitting the ground staff, nor too late, can not let the astronauts wait too long.
At present, the mainland search and rescue team has been able to achieve "cabin drop", and the timing card is just right.
Who is better than the United States?
Since the decommissioning of the space shuttle in 2011, the United States has not had a new manned spacecraft, until the successful development of SPACE X's Dragon spacecraft in 2020, sending astronauts to the International Space Station, only to restart the history of manned spaceflight in the United States.
From the perspective of the return time, Compared with the three countries of China, the United States and Russia, Russia is superior.
The American Dragon spacecraft takes 6-20 hours to return to Earth. Among them, on August 2, 2020, the Dragon spacecraft took 19 hours to pick up two astronauts from the International Space Station and return to Earth; the "Tenacity" spacecraft took about 6.5 hours to return to Earth.
The SpaceX Dragon spacecraft has 7 potential splashdown zones around Florida, located in the Gulf of Mexico and the Atlantic Ocean. Depending on the splash site chosen, it will take the crew 6 to 30 hours to return to Earth after unraveling with the International Space Station.
The shortest return time is Russia, whose return capsule can return to Earth from the International Space Station in just 4 hours, bearing in mind that the height of the International Space Station and the height of the Continental Space Station are almost the same.
The reason why it can be so fast is because the Russian spacecraft can only circle the earth twice, find the brake ignition point, open the return procedure, and let the spacecraft land.
From this point of view, although the mainland's rapid return technology is powerful, it is not the fastest, but the mainland space started late, with the accumulation of continental space technology, the future mainland return time can be shortened.
From the perspective of accuracy, the accuracy of the landing site and the actual landing site of the mainland return capsule is very high, only 130 meters, which can be described as one of the world's first-class countries, even compared with the United States and Russia.
In fact, since the mainland opened the manned space mission, there has not been a serious deviation from the scheduled landing site, as well as serious disaster accidents, and the United States and Russia have had disaster situations, and even led to the sacrifice of astronauts, from this point of view, the mainland manned return technology, has been looking for breakthroughs in the smooth, while ensuring the safety of astronauts, do further performance improvement, there may be more surprises in the future.