"He Han is vertical and horizontal, Beidou horizontally straightens." Since ancient times, the Big Dipper is like a lighthouse in the Tianhe River, which has attracted people's scorching eyes to identify the direction and plan for four o'clock.

  On June 23, China successfully launched the last global networking satellite of Beidou-3 with the Long March 3B rocket at the Xichang Satellite Launch Center. So far, the deployment of the constellation of Beidou-3 global satellite navigation system has been completed.

Photography: Hu Xujie

Photography: Hu Xujie

Photography: Hu Xujie

  Counting from the launch of the first Beidou navigation test satellite in 2000, in 20 years, China used 44 launches to successfully send 59 Beidou navigation (test) satellites into space with a success rate of 100%.

  Over the past two decades, the Chinese astronauts have been self-reliant and thorny, and have deployed the Beidou "big game" in space. Today, the Beidou global satellite navigation system has changed from unreachable to autonomous.

  As early as the 1980s, China began to explore the development path of satellite navigation systems suitable for national conditions. In 1983, experts and scholars represented by the "two bombs and one star" Yuan Xun, academician of the Chinese Academy of Sciences Chen Fangyun proposed the use of two geostationary orbit satellites to determine ground and air targets. Through a large number of theoretical and technical research work, Double Star The concept of positioning system is gradually clear.

  On the basis of the double-star positioning system, China Beidou followed a "three-step" strategy, starting with active and then passive, followed by regional and global, and embarked on a road of satellite navigation system construction with Chinese characteristics.

Beidou-3 satellite. Photo courtesy of China Academy of Space Technology

  Since its birth, the Beidou system has formed an indissoluble bond with the "three".

  The Beidou project implements the "three-step" strategy. According to the plan, China will build the Beidou No. 1 system at the end of 2000 to provide services to China; the Beidou No. 2 system will be built at the end of 2012 to provide services to the Asia-Pacific region; and the Beidou No. 3 system will be built to provide services to the world in 2020.

  As Xie Jun, deputy chief designer of the Beidou No. 3 project and chief chief satellite designer of the China Academy of Space Technology, a subsidiary of China Aerospace Science and Technology Corporation, said, Beidou No. 1 broke the foreign technology monopoly and established the world's first double-star positioning principle based on Regional active satellite positioning system; Beidou-2 overcomes a number of key technologies represented by the overall technology of navigation satellites, high-precision spaceborne atomic clocks, etc., so that the "heart" of the satellite navigation system beats the Chinese heart rate; Beidou-3 is even more Taking the lead, started the journey from running side by side to leading.

Xie Jun, deputy chief designer of Beidou No. 3 project and chief chief designer of satellite system. Photo courtesy of China Academy of Space Technology

  In the context of the US GPS, Russian Glonas, European Galileo and other navigation systems have deployed a single orbit satellite constellation, China Beidou is unique, using three orbit satellites to form a hybrid navigation constellation.

  The Beidou-3 system consists of 3 tilted geosynchronous orbit (IGSO) satellites, 24 medium-circle earth orbit (MEO) satellites and 3 geosynchronous orbit (GEO) satellites. This mixed constellation of different types of orbits is unique to the Beidou system and is an international initiative, which can effectively increase the number of satellites visible in the Asia-Pacific region.

  As a domestic satellite navigation system, Beidou system also has many advantages that other satellite navigation systems do not have, and short message service is one of them.

  On April 14, 2007, China successfully launched the first satellite of Beidou-2 system at the Xichang Satellite Launch Center. Photo courtesy of China Satellite Navigation System Management Office

  On October 25, 2012, the 16th Beidou Navigation Satellite was launched and entered a predetermined orbit, marking the completion of the deployment of the Beidou-2 system engineering constellation. Photo courtesy of China Satellite Navigation System Management Office

  An earthquake broke out in Wenchuan, Sichuan in 2008. In the epicentre Yingxiu, there was no news for more than 20 hours. The troops and soldiers who rushed through the death line sent a short message of more than 100 words through the Beidou system. After the dead zone of ground communication signals or other communication methods failed, Beidou's short message service became the last "lifeline" to save lives in an emergency.

  Looking back at the past, countless wonderful moments are worth being remembered. In 1994, the Beidou-1 system project was established, the Beidou-1 system was completed in 2000, the Beidou-2’s first satellite was launched in 2007, the Beidou-2 regional satellite navigation system was completed in 2012, and the core constellation of the Beidou global system was deployed in 2019...

  On November 5, 2017, China successfully launched the first batch of Beidou-3 satellites in a "one arrow, two stars" manner. Photo courtesy of China Satellite Navigation System Management Office

  At 15:22 on December 16, 2019, China successfully launched the 52nd and 53rd Beidou navigation satellites in a "one arrow, two stars" manner, which marked the completion of the deployment of the core constellation of the Beidou-3 global system. Photo courtesy of China Satellite Navigation System Management Office

  20 years of extraordinary course, enough to make a young boy Lang Shui Hua early. The Beidou people represented by Yang Changfeng and Xie Jun grew together with the Beidou project. As the chief designer of Beidou Satellite Navigation System Engineering, Yang Changfeng is now a snow-stained temple. He participated in or presided over the demonstration design, engineering construction and organizational management of the third-generation Beidou Satellite Navigation System throughout the process, witnessing the growth of Beidou all the way.

  In the glorious 20 years, China has completed the construction of the third generation system of Beidou No. 1, Beidou No. 2, and Beidou No. 3. The Beidou satellite navigation system completely broke the long-term dependence of core components on imports and was controlled by people, casting the "Chinese soul" and eventually becoming a "big weapon".

  Tianhe is full of Beidoucan, and now the last Beidou-3 global networking satellite is launched, but this is not the end, and the Beidou system will continue to be upgraded and improved in the future. Looking ahead, Yang Changfeng said that by 2035, China will build a more ubiquitous, more integrated, and more intelligent national integrated positioning and navigation time service (PNT) system to further enhance its spatial and temporal information service capabilities. At that time, Beidou will serve the world and benefit mankind with stronger functions and better performance.

The moment when the Changjiajia Rocket launched the Beidou satellite. Photo courtesy of China Academy of Launch Vehicle Technology

  Author: Guo Chaokai