Technical Interpretation | How was the first lesson of “Tiangong Classroom” transmitted back to Earth?

At 15:40 on December 9, the first class of "Tiangong Classroom" was officially opened in the space station. Astronauts Zhai Zhigang, Wang Yaping and Ye Guangfu of the Shenzhou 13 crew showed the working and living scenes of the Chinese space station in orbit, demonstrated cytological experiments, object movement, liquid surface tension and other phenomena in a microgravity environment, and communicated with the ground classroom in real time. Do you know how stable and clear pictures and sounds are transmitted back from nine days away?

Comprehensive coverage of the measurement and control system, establishing a road for space-ground communication transmission

The reporter learned from China Electronics Technology Group that in order to achieve interconnection and instant communication between heaven and earth, the communication measurement and control system developed by China Electronics Research has created a broadband, efficient and stable communication transmission "sky road" between heaven and earth to meet the "ultra-long standby" requirements.

The measurement and control system has comprehensive coverage, establishing a high-speed sky road for communication transmission between the sky and the earth. In the land-based measurement and control stations and relay satellite systems, China Electronics Technology Group Corporation has woven a measurement and control communication network that achieves 100% coverage from different dimensions. The unified measurement and control system spread across various measurement and control sites is networked and operated with relay satellites set up 36,000 kilometers in space, creating a broadband, efficient and reliable communication transmission sky road between the sky and the earth, providing image transmission between the sky and the earth.

The Tianlian-1 ground terminal station manufactured by China Electronics Technology Group Corporation is an important component of the data relay satellite system and is the key to ensuring the transmission of information between the earth and the sky. In order to meet the mission requirements of the space station, China Electronics Technology Group Corporation has upgraded and renovated the Tianlian-1 ground terminal station, realizing the automatic allocation of link resources and automatic fault handling, improving the reliability of mission operation, and shortening the mission preparation and fault handling time.

The mutual backup of the ground-to-space links can ensure that no matter how the spacecraft's flight orbit and position change, the ground can stably receive signals and support the completion of space teaching.

The communication system is fully upgraded to facilitate real-time communication interaction

Satellite communication equipment serves as the "clairaudience" and "clairvoyance" between heaven and earth. It is the management and command center for voice and images between heaven and earth. It is responsible for sending key data such as voice, images, and measurement and control from each measurement and control site to the center to provide support for command decisions.

In order to meet the requirements of the manned space station and Shenzhou spacecraft missions for communication systems, China Electronics Technology Group Corporation has newly built multiple fixed stations, vehicle-mounted stations and portable stations, and upgraded the hardware and software of satellite communication equipment. In the newly built and upgraded systems, high-power amplifiers and other equipment independently developed and produced are used, and the system transmission capacity is increased by 5 to 10 times. The satellite communication transmission capacity is greatly improved, which can meet the requirements of long-term data transmission in orbit of manned space stations.

In order to see clear images on TV, the space-ground image codec terminal is needed to encode and compress the audio and video. The various space-ground image codec terminals newly developed by China Electronics Technology Group Corporation can meet the requirements of multi-cabin and multi-scene space-ground image transmission in manned space stations, complete the transmission of various types of image information such as low-speed images, high-definition images and panoramic pictures, and build a visualization platform for the connection between the sky and the earth.

At the same time, according to Yi Yusheng, chief designer of the measurement, control and communication subsystem of the space station system of the Fifth Academy of China Aerospace Science and Technology Corporation, this space-to-earth teaching is based on my country's Tianlian relay system, using high-speed two-way audio and video transmission, and is carried out in interactive forms such as space-to-earth dialogue. Multiple high-definition cameras are used in the cabin to transmit high-definition video to the ground in real time through a relay high-speed link, and two high-definition images on the ground are sent to the cabin display, thereby realizing two-way video transmission. In order to ensure the smooth implementation of the teaching with high reliability and high level, the development team conducted multiple full-process collaborative drills on the teaching process and the space-to-earth collaborative procedures. During the teaching process, the ground staff monitored the status of each device on the space station in real time, and monitored the status of the space-to-earth link at the same time to ensure that all equipment involved in the teaching is working properly, helping astronauts to teach in space more easily.

Scene lighting technology is used in a large manned spacecraft for the first time

After the space lecture began, the images of students listening attentively on the ground appeared synchronously in the core module of the space station. Wang Yaping could clearly see the children's every move through a large LCD screen. This large screen is one of the important equipment of the instrument and lighting subsystem.

Image source: @Xinhua News Agency

Li Wanling, chief designer of the instrument and lighting subsystem of the space station system of the Fifth Academy, introduced that the instrument and lighting subsystem is one of the subsystems with the most astronaut participation in the space station system. It has human-computer interaction functions and can provide an interactive and operating platform for astronauts to operate the space station. At the same time, it provides environmental lighting for astronauts' work, life, extravehicular activities, rendezvous and docking tasks during their in-orbit period. Many devices and technologies used in its display, hand control and lighting subsystems are very novel, unique and tend to be at the forefront of related technical fields. The LCD screen, which plays an important role in the lecture, is a new generation of distributed digital remote terminal equipment that integrates multiple functions such as graphic image display, streaming media and video playback, alarm drive, command sending, earth-ground text interaction, touch operation, multi-bus communication, and support for user in-orbit dynamic configuration. As a human-computer interaction instrument, it is the "display" of astronauts, providing astronauts with information on the health status of the space station, and continuously escorting the operation of the space station and the safety of astronauts.

As early as the beginning of the design and construction of the space station, the designers of the Fifth Academy adhered to the people-oriented design concept, always put the astronauts' on-orbit life experience first, and tried every means to make their lives more convenient and their work more efficient. Since the space station will periodically pass through the shadow area of ​​the earth during its orbital flight, the lighting problem is particularly important. Astronauts' work, life and other activities in the space station are inseparable from lighting equipment. Li Wanling introduced that the lighting subsystem can provide indoor and outdoor lighting support for the space station assembly. The lighting products mainly include scene lighting, portable lighting and outdoor floodlighting. The space station lighting subsystem is the first time that my country has applied scene mode adjustable lighting technology on a spacecraft, and it is also the first time in the world that scene lighting technology has been fully applied inside a large manned spacecraft.

In long-term work and life in orbit, a single lighting mode can easily cause astronauts to have reduced work efficiency, disrupted biological clocks, and sleep disorders. Situational lighting can solve many of the above problems through controllable adjustment of color temperature, brightness, and lighting areas. The lighting area can be divided into work area, living area, reading area, maintenance area, etc., ensuring that astronauts have desk lamps for work, dining lamps for meals, night lights for sleep, reading lamps for reading, and lighting lamps for entertainment. In addition, astronauts have special headlamps when repairing equipment, and emergency lighting for escape and self-rescue in case of danger. When these lamps are turned on and off, in addition to using the switch board wired control like we usually turn on and off the lights at home, they also add the Wifi wireless control function of handheld mobile devices. Astronauts can control the lights on and off, adjust the brightness, color temperature, etc. through the mobile phone APP. These humanized designs provide a warm and comfortable home for astronauts to work and live in orbit.

◎ Pang Dan, Wang Xuejiao, Science and Technology Daily reporter Fu Yifei

Source: Science and Technology Daily

Editor: Zhang Qiqi

Review: Julie

Final review: Liu Haiying