Science

Land, sea and space-based measurement and control network: linking heaven and earth to "escort" the Chinese space station

Source: Study Army Corps - China Military Author: Lv Binghong Liberation Army Newspaper reporter An Pu Zhong Wang Ling Shuo

On June 5, Shenzhou XIV manned spacecraft aboard the Long March II F Yao XIV launch vehicle lifted off and completed a rapid autonomous rendezvous and docking with Tianhe core module. The third batch of Chinese space station astronauts space journey officially kicked off.

After the spacecraft lifts off, it maintains contact with the ground through the measurement and control communication system. As one of the seven systems of China's manned space project, the measurement and control communication system plays an extremely important role in all phases of the manned space mission.

The Unified S-band Measurement and Control System (USB) is favored by major spacefaring nations for its high reliability, high accuracy, high real-time, and high data rate.

Since the inception of China's manned space program, after 30 years of exploration and practice, China has built a unified S-band measurement and control network with comprehensive land, sea and space-based coverage, and its comprehensive performance has reached the international advanced level.

Land and sea space-based measurement and control network -

Linking heaven and earth to "escort" the Chinese space station

Lv Binghong, PLA reporter An Pu Zhong, Wang Ling Shuo

Land, sea and space-based measurement and control network: linking heaven and earth to "escort" the Chinese space station

Kashgar measurement and control station of Xi'an Satellite Measurement and Control Center. Photo by Lv Long

USB measurement and control network, born in the human moon landing project

In the late 1950s, Korolev, a Soviet rocket expert, led a team that transformed the missile into a 58-cm-diameter, 83.6-kg sphere, then fitted it with four whip antennas and some scientific instruments. This was the first artificial satellite of mankind.

On October 4, 1957, the Soviet Union launched the Sputnik I satellite into space. Since then, mankind has started the journey of space exploration.

This artificial satellite is loaded with two radio transmitters inside and sends signals to Earth every 0.3 seconds. By receiving these signals, the ground can measure the satellite's position information and track it.

The satellite passes over Moscow 2 times a day. For the people of the Soviet Union in those days, when they looked up at the stars on a clear autumn night, if they saw a star moving among the stars, it was definitely Sputnik-1.

Unfortunately, the first human-made satellite was only in the sky for 92 days before it crashed into the atmosphere and burned up.

In April 1961, the Soviet Union was one step ahead of the United States in the manned space program again when cosmonaut Gagarin set sail from the Baikonur launch site in the Vostok 1 spacecraft, orbiting the Earth at a maximum altitude of 301 kilometers in 1 hour and 48 minutes.

The first and second rounds of the space race were lost one after another, allowing the United States to put its last "flip" hope on a manned moon landing.

The ground-based measurement and control networks used by the U.S. on the Mercury and Gemini manned space missions used different bands and frequencies, allowing many transmitters and receivers to be set up on the spacecraft, greatly increasing the weight, power consumption, and operational complexity of the spacecraft equipment.

To change this situation, the National Aeronautics and Space Administration (NASA) adopted a proposal from the Jet Propulsion Laboratory (JPL) to use S-band (2000-4000 MHz) microwave unified measurement and control technology. With this technology, they intend to create a radio measurement and control system that combines the functions of spacecraft tracking and orbiting, telemetry, remote control and heaven and earth communication into one.

This "unified measurement and control system" modulates various information on different frequency sub-carriers and packages them into a single carrier wave. The receiver then demodulates the carrier, and then decomposes and distributes the sub-carriers with different frequency filters, converting them into original information such as voice, image, telemetry, etc., so that they can be used for track measurement, telemetry, remote control, digital transmission and voice. Meanwhile, the pseudo-random code ranging technology adopted by the system can complete the ranging problem of lunar orbit at a distance of 380,000 km away.

In 1966, the unified S-band measurement and control system (USB) for the Apollo moon landing was officially put into use, and the space measurement and control was thus improved from a single-function decentralized system to an integrated multifunctional system. The U.S. set up nearly 20 USB stations in the belt area from 40°N to 40°S, which covered dozens of Apollo missions. Later, the network was also involved in other NEO and GEO satellite missions.

In 1979, the World Radio Control Conference held in Geneva formally decided to use S-band as the space operation band and gradually replace the VHF ultra-short wave band commonly used by countries. Since then, some countries and organizations, such as France and ESA, have decided to build USB measurement and control networks in this way.

In the mid-1980s, with the emergence of new technologies, new processes and new devices, the major spacefaring countries, represented by France, realized the miniaturization, digitalization and automation of USB measurement and control networks, which can be compatible and networked with other countries using the same frequency and the same transmission standards. Its software algorithms and management methods, compared to the old days dedicated to the "Apollo" mission to build the USB measurement and control network has made great strides.

China USB measurement and control network became famous in one "battle"

In 1992, China's manned space program was officially launched, and the demonstration, design and development of the measurement and control communication system began immediately. Through decades of development, China has successfully built a unified S-band space measurement and control network with Chinese characteristics and reaching international advanced level.

In order to ensure that the Shenzhou spacecraft has measurement and control communication support in key flight segments, the Xi'an Satellite Measurement and Control Center has set up the Qingdao measurement and control station near the Yellow Sea, installed additional USB measurement and control equipment in Kashgar, Weinan, Xiamen and other measurement and control stations, and deployed active measurement and control stations in the landing site area and other places.

Today, the land-sea-based USB measurement and control network consisting of three major centers in Dongfeng, Beijing and Xi'an, related ground stations, and the survey vessel Yuanwang has taken shape. The measurement and control network is internationally compatible in terms of frequency band and system, integrating orbit measurement, telemetry, remote control, voice, TV and other functions, integrating measurement and control and heaven and earth communication, which can support the measurement and control of China's manned spacecraft, all low- and medium-orbit satellites, as well as the measurement and control tasks of S-band synchronous orbit satellites.

At 9:00 p.m. on October 15, 2003, the Shenzhou V manned spacecraft was launched from the Jiuquan Satellite Launch Center under the full attention of the public.

"Qingdao, ship-arrow separation!" At about 9:00, the Shenzhou V spacecraft and the Long March IIF launch vehicle completed the separation of the ship and arrow in the measurement and control arc of Qingdao station. 1 minute later, the ship of Faraway 1 issued a solar sail deployment command to the spacecraft, and the Shenzhou V spacecraft carrying China's first astronaut Yang Liwei entered the scheduled orbit smoothly. As the measurement and control stations and ships started measurement and control one after another, the moment of Yang Liwei displaying the national flag in space was spread to thousands of households through the measurement and control network. At the same time, a clear and loud "normal" from each participating station and ship made all the people on the ground worried about it extraordinarily at ease.

After 14 laps of flight, at 05:35 on Oct. 16, Beijing Space Flight Control Center sent the return command to the spacecraft, and the Far Horizons 3 survey vessel and overseas measurement and control stations along the way sent orbit-return separation and return braking commands to the spacecraft one after another. The spacecraft successfully returned to the sky over the motherland.

Through the measurement of telemetry data, Beijing Space Flight Control Center and Xi'an Satellite Measurement and Control Center successively calculated the predicted landing point of the return module. 6:23 p.m., the return module successfully landed at the main landing site in Siziwangqi, Inner Mongolia, only 13 minutes later, the search and rescue personnel successfully found the return module, China's first manned space mission was a complete success.

Shepherding the arrow to catch the boat, holding the Shenzhou spacecraft to travel in space. Along with Yang Liwei on behalf of China's first feat of space flight, China's USB measurement and control network a "war" to become famous.

Connecting heaven and earth to create more Chinese space miracles

On September 27, 2008, astronaut Zhai Zhigang, dressed in a "flying" extravehicular space suit, slowly explored his body from the orbital module of Shenzhou VII spacecraft. With hundreds of millions of viewers around the world watching, Zhai Zhigang received the five-star red flag handed to him by Liu Booming. In the vast space, the national flag that a touch of red dazzling.

Meanwhile, the measurement and control stations and ships deployed on the ground and at sea are carrying out a relay race across 10,000 miles. An unprecedented scale of land and sea-based measurement and control belt composed of more than 10 ground-based measurement and control stations and 5 Yuanwang measurement ships, which guaranteed continuous measurement and control communications between the ground and the spacecraft for more than 40 minutes, enabled Zhai Zhigang's "walk in space" to be displayed in front of the world without interruption.

However, the use of such a large scale of land and sea-based measurement and control resources for the measurement and control of a single target can no longer meet the future needs of China's manned spaceflight. Spacecraft rendezvous and docking with the space station, astronauts in the space station long-term residence ...... which put forward higher requirements for the measurement and control system.

Shortly after Zhai Zhigang returned to the spacecraft, in a synchronous orbit more than 36,000 kilometers from Earth, the Skylink 01 star successfully captured the spacecraft's signal using its own relay measurement and control antenna, and sent the telemetry and image data received by this satellite to the ground for the first time.

As one of the four major scientific experiments of the Shenzhou VII mission, the space-based data relay moved the measurement and control station from the ground to space. Compared with ground-based stations, relay satellites are less affected by the curvature of the Earth, and only this one relay satellite can greatly improve China's coverage of Shenzhou-7 spacecraft, and the network of three relay satellites can make the measurement and control rate of the spacecraft reach nearly 100%.

This is the technology system that aerospace measurement and control people have been dreaming of for decades, and it is a necessary path for the future of China's aerospace measurement and control industry.

In 2012, after four years of launch and deployment, the three relay satellites finally formed China's first space-based measurement and control network.

On June 20, 2013, "space teacher" Wang Yaping gave a 51-minute "space lecture" to primary and secondary school students in the Tiangong-1 test module; on the evening of October 21, 2016, the ground successfully transmitted TV signals to the Tiangong-2 space laboratory via the Skylink-103 star, and astronauts Jing Haipeng and Chen Dong watched the synchronized broadcast of news from heaven and earth for the first time; on April 29, 2021, the Tianhe core module was successfully launched, and the Chinese space station was built. On the night of October 21, 2016, the ground successfully transmitted TV signals to the Tiangong-2 space laboratory through the Sky Link 03 star, and astronauts Jing Haipeng and Chen Dong were able to see the simultaneous broadcast of "Newswire" from heaven and earth for the first time; on April 29, 2021, the core module of Tiangong-1 was successfully launched, and the curtain of the construction of the Chinese space station was officially opened. ...... With the increasingly perfect USB measurement and control network, astronauts can talk, send and receive emails from heaven and earth. Email restrictions and costs are getting lower and lower, and the user experience is getting better and better, and the long journey to space inside the future space station will be more colorful.

Yang Yongan, a senior engineer at the Xi'an Satellite Measurement and Control Center, told reporters that during the construction of the space station in orbit, the return trajectory of the Shenzhou spacecraft span a wide range of changes. In addition, Shenzhou XIV mission, ask the sky, dream sky experiment module launched one after another, the flight crew in orbit during the residence, will cooperate with the ground to complete the space station assembly and construction work, and experience nine combinations of body configuration, five rendezvous and docking, three separation and withdrawal and two transposition tasks, the complexity of the mission in orbit will become the most... ...these changes in the state of technology on the measurement and control communication system also put forward higher requirements.

In space, the space-based measurement and control network composed of multiple sky chain relay satellites is involved in manned space missions as the main measurement and control means, and provides space-based measurement and control and data relay support at important mission nodes such as rendezvous and docking and capsule activities.

With the strong support of space-based measurement and control, the fleet of COSCO only needs to send one measurement vessel to participate in the Shenzhou XIV mission, and it can return after completing the rendezvous and docking measurement and control tasks, which greatly saves the cost of going to sea. The spectacular scenes of the Shenzhou VII mission in which five Yuanwang survey ships were deployed in the ocean have become history.

As the "old" mainstay of manned space missions, the land-based USB measurement and control equipment will complement each other with its stable and reliable performance and relay satellites to jointly escort the astronauts' journey into space.

Keeping heaven and earth close at hand. During the six-month space journey of the Shenzhou XIV crew, China's USB measurement and control network will take on the important task of connecting heaven and earth and creating more Chinese space miracles.

(Produced by the Learning Corps - China Army)