Summary:At 20:09 on December 4, the return module of the Shenzhou 14 manned spacecraft successfully landed at the Dongfeng Landing Field, and the Shenzhou 14 manned flight mission was a complete success.
At 20:09 on December 4, the return module of the Shenzhou 14 manned spacecraft successfully landed at the Dongfeng Landing Field, and the Shenzhou 14 manned flight mission was a complete success.
The return of the Shenzhou 14 crew is the first return mission after the completion of the “T” basic configuration of the Chinese space station. It is also the first time for a manned spacecraft to return to the Dongfeng Landing Field at night in winter. With the state of technology since then, using the fast return mode, the return and flight around the earth has been shortened from 18 laps to 5 laps, and the return time has been shortened by nearly 20 hours. Compared with previous missions, low temperature and dark night are the two major challenges of this mission. Faced with the test, the Chinese scientific research team innovated a number of technical methods to escort the crew of Shenzhou 14 to return home smoothly.
Thermal control system makes astronauts’ journey home warmer and more comfortable
At the Dongfeng Landing Site in December, the cold wind blows against the Gobi desert, and the extreme temperature at night is as low as minus 20 degrees Celsius. Many people are concerned about how to keep the astronauts on the Shenzhou 14 crew warm during their journey home?
According to Peng Huakang, overall technical director of the manned spacecraft recovery test team of the Fifth Academy of Aerospace Science and Technology Group, when the manned spacecraft is separated from the space station, the thermal control subsystem on the spacecraft will take over the temperature and humidity control and control the temperature of the airtight cabin at 17°C. degrees Celsius to 25 degrees Celsius.
The measures taken by this system include active thermal control and passive thermal control. Passive thermal control refers to the heat-resistant materials, coatings, and fans in the cabin of the spacecraft; active thermal control includes heating sheets and radiators in the spacecraft.
During the process of entering the atmosphere, due to severe friction with the atmosphere, the temperature of the return cabin will increase to a certain extent. However, by means of thermal control pre-cooling, the temperature in the return cabin can be lowered in advance, and at the same time, the ablation and sublimation of the ablation material on the surface of the return cabin will take away a large amount of heat.
After the return capsule lands, it is mainly the passive insulation performance of the cabin that plays a role. “Through simulation calculations, if the return capsule lands in a desert at minus 25 degrees Celsius, the temperature inside the cabin can be kept above 15 degrees Celsius for an hour without opening the hatch and ventilation fans,” Peng Huakang said.
The reporter learned from the China Astronaut Center that in view of the low temperature and dark night environment, researchers have newly developed a warming device for astronauts, added a series of measures for auxiliary lighting, and optimized the workflow of medical supervision and medical insurance at the same time, reducing the exposure time of astronauts outside the cabin, ensuring In order to enter the carrier in time to carry out medical supervision and medical insurance related work.
The communication measurement and control network creates “bright eyes” for the safe return of the spacecraft
From the speed change of the return capsule into the return orbit to the separation of the propulsion module and the return capsule, from the entry of the return capsule into the atmosphere to the safe landing… Every step of the return requires a measurement and control system to receive and send instructions, and the layers of traction escort the return journey.
At the main landing site, CETC deployed a multi-station satellite communication system and a multi-model measurement and control system, and upgraded the satellite communication equipment to increase the transmission capacity by 5 to 10 times. The newly developed Beidou situation system in the recovery area uses the positioning and short message functions of the Beidou navigation system to build a trinity command system of command center, forward command, and search platform, which greatly improves the search efficiency of the return cabin and shortens the recovery time.
Since the return capsule of Shenzhou 14 entered the atmosphere, the measurement radar of the Second Academy of Aerospace Science and Industry Corporation has started tracking and measuring real-time data like a “bright eye”.
The “black barrier area” formed when the return capsule enters the atmosphere will isolate the communication between the return vehicle and the ground monitoring and control station. In order to solve this problem, the 23rd Institute of the Second Academy of Aerospace Science and Industry Corporation independently developed the phased array measurement radar “Recovery No. 1”. The radar performing this mission has absorbed the experience of previous missions and optimized its design.
The dual challenges of darkness and extreme cold put forward higher requirements for directional search and rescue equipment. Song Lei, head of the manned space mission team of the 22nd Institute of CETC, introduced that during this mission, the scientific research team strengthened the construction of an integrated space-ground search and guidance system, and the newly developed radio station for talking to astronauts was seamlessly connected with the measurement and control system at the landing site. The connection, for the first time, “extends” the call voice of the astronauts in the cabin to the Beijing Flight Control Center.
In addition, the search and guidance system in the front cabin of the helicopter conducts in-depth fusion and intelligent decision-making for multi-source search and rescue information on the landing site, which helps the search helicopter to predict the trajectory of the return capsule in advance from a long distance, and wins valuable “sports” for the search mission. Amount in advance”.
The deceleration buffers are interlocked to achieve a “gentle” landing
Peng Huakang introduced that since the return capsule entered the atmosphere, as the carbonization and ablation of the heat-resistant material on the surface of the capsule took away a large amount of heat, the flight kinetic energy of the return capsule continued to decrease, and the speed gradually decreased from 7.9 kilometers per second to several hundred meters per second.
When it was about 40 kilometers away from the ground, the spacecraft had basically left the “black barrier area”. The static pressure altitude controller installed on the return capsule judges the altitude by measuring the atmospheric pressure. When the return capsule is about 10 kilometers away from the ground, the guide parachute, deceleration parachute and main parachute are opened one after another. The area of the three parachute varies from a few square meters to Gradually increased to more than 1000 square meters. This set of parachutes reduces the speed of the return capsule from 200 meters per second to 7 meters per second, achieving the purpose of reducing overload and protecting astronauts.
Shortly after the main parachute is fully opened, the gamma altitude control device in the return cabin starts to work, and measures the altitude from the ground in real time by emitting gamma rays.
When the return capsule drops to a height of 1 meter from the ground, the gamma altitude control device at the bottom sends out an ignition signal, and the four reverse thrust engines on the cabin ignite to generate an upward momentum, so that the landing speed of the return capsule reaches 1 to 2 meters per second. At the same time, the astronaut’s seat with the cushioning device will start to lift before landing, further reducing the landing impact of the astronaut and achieving a “gentle” landing.
Original Title: Winter Night Returns Technology Power Escorts Shenzhou 14 to Return Home