On 25 April, the Shenzhou-18 spacecraft was successfully launched, and astronaut Ye Guangfu became the second astronaut from the mainland to return to China's space station! In the previous Shenzhou-17 mission, astronaut Tang Hongbo became the first Chinese astronaut to return to China's space station, and on the basis of participating in the Shenzhou-12 and Shenzhou-17 missions, astronaut Tang Hongbo also became the mainland's astronaut with the longest time in orbit, and the cumulative time in orbit was nearly nine months. However, this record is about to be broken by astronaut Ye Guangfu.
In October 2021, astronaut Ye Guangfu, Zhai Zhigang and Wang Yaping carried out the Shenzhou-13 mission together, and during the Shenzhou-13 mission, the three astronauts lived and worked in the Chinese space station for six months. Now astronaut Ye Guangfu has successfully launched on the Shenzhou 18 spacecraft, and plans to fly for 6 months, that is to say, when Ye Guangfu finishes the Shenzhou 18 mission, his orbit time will reach 1 year, and he will become the astronaut with the longest orbit time in the mainland.
Shenzhou 18 Expedition
On the evening of April 25, the Shenzhou-18 spacecraft was successfully launched, sending a flight crew composed of three astronauts Ye Guangfu, Li Cong and Li Guangsu into space, starting a six-month space flight journey. Speaking of the Shenzhou 18 spacecraft, everyone can actually be said to be impressed.
Because this spacecraft began to enter everyone's sight half a year ago, when the Shenzhou 17 spacecraft was launched, the Shenzhou 18 spacecraft began to be on standby, always ready to escort the astronauts of Shenzhou 17. After almost half a year of standby duty, the Shenzhou-18 spacecraft moved to the launch stage and has now been launched to carry out the next stage of the mission.
According to the plan, the three astronauts of the Shenzhou-18 spacecraft will complete more than 90 experiments and experiments during their stay in orbit, and some scientific experiments will be carried out for the first time on the mainland. For example, they will implement the first in-orbit aquatic ecology research project in China, using zebrafish and goldfish algae as research objects, and establish a stable operation of the space self-circulating aquatic ecosystem in the space station, achieving a breakthrough in the continent's cultivation of vertebrates in space. In addition, they will also conduct the world's first on-orbit study of plant stem stem cell function. Judging from the arrangement of these missions, the astronauts of Shenzhou 18 will create many firsts.
In addition to these scientific researches, the astronauts also need to complete a series of normalized work, one of which is to complete the on-orbit handover and rotation with the astronaut crew of Shenzhou-17, and when the handover and rotation are completed, the Shenzhou-17 spacecraft will be evacuated and returned to Earth. In late October, the Shenzhou-18 spacecraft will return to Earth, and before returning to Earth, the astronauts of Shenzhou-18 will welcome the arrival of Shenzhou-19 astronauts, and then complete the on-orbit handover and rotation again.
According to the plan, the astronauts of Shenzhou-18 will complete 6 missions and 2 to 3 out-of-cabin activities. In the process of out-of-cabin activities, astronauts need to install debris protection and reinforcement devices on extravehicular pipelines, cables and key equipment, and also need to carry out extravehicular inspection work according to the situation.
Why was the ship burned beyond recognition?
I believe that many friends have seen the process of launching the spacecraft, and have also seen the picture of the spacecraft returning to the earth. Also passing through the earth's atmosphere, why does the spacecraft not burn violently during the launch process, but burns violently during the return to the earth, and the outside of the spacecraft's return capsule will be burned beyond recognition?
Why does it burn violently when returning home: The reason is actually very simple, the spacecraft flying in outer space is quite fast, and the spacecraft in low-earth orbit are flying at or close to the first cosmic speed of the Earth, which is about 7.9 kilometers per second. Flying farther to the Moon, Mars, Venus and other celestial bodies, spacecraft fly faster, generally reaching or exceeding the Earth's second cosmic velocity of 11.2 kilometers per second. When these spacecraft return to Earth at such a rapid rate, they inevitably burn violently.
Because the Earth is a planet with a dense atmosphere, when these spacecraft break into the Earth's atmosphere at a fairly fast speed, the aerodynamic heating effect on the outside of the spacecraft will be very strong, and the external temperature will generally reach one or two thousand °C, and can even reach about 3000 °C. This is only the case on planets with atmospheres, and the probe will also burn violently when it lands on Mars.
Since the temperature on the outside of the spacecraft was quite high when it returned to Earth, the outside of the spacecraft seemed to be surrounded by raging fire. When spacecraft such as rocket wreckage, satellite wreckage, cargo spacecraft, spacecraft propulsion module, orbital module and other spacecraft return to the Earth's atmosphere, they will burn violently in the atmosphere and turn into ashes. The manned spacecraft return capsule will not be burned out and can safely land on the ground or the sea.
This is because when astronauts enter or return to Earth from outer space, they are in the spacecraft return capsule, and they wear in-cabin spacesuits. The exterior of the spacecraft's return capsule is also coated with ablative materials and thermal insulation materials, and when returning to the earth's atmosphere, under the high temperature of one or two thousand °C, the external ablative materials will fall off and take away a lot of heat.
Therefore, when we see the return capsule of the manned spacecraft returning to Earth, it is like a raging fireball falling from the sky, with sparks all the way behind. Despite the scorching heat, the ship's return capsule did not burn out, and the internal temperature was comfortable. It's just that under the scorching heat of such a high temperature, the exterior of the spacecraft's return capsule was burned black beyond recognition.
Why doesn't it burn when launched: Although they all pass through the earth's atmosphere, the speed of spacecraft and rockets is actually very slow during launch. Because the weight of the rocket and spaceship combination itself is very large, the acceleration at the beginning is not large, so at low altitude, the speed of the spacecraft and rocket combination is not fast.
With the continuous combustion of fuel, the weight of the rocket and spacecraft assembly continues to decrease, and the speed is getting faster and faster, but after entering the high altitude, the air density is getting smaller and smaller, and the aerodynamic heating effect is not enough to make the temperature of the rocket and spacecraft assembly reach the level of violent combustion, and naturally there will be no violent combustion.