XI'AN, Jan. 25 (China News Service) — Developing all payloads for the BeiDou-1 and BeiDou-2 satellites, and providing all payloads for 20 of the 30 BeiDou-3 satellites that realize global networking... Over three decades, the Xi'an Branch of the Fifth Academy of China Aerospace Science and Technology Corporation (hereinafter referred to as the Xi'an Branch), as the core unit for the overall design of China's BeiDou navigation satellite payloads and the development of system products, has driven China's BeiDou Satellite Navigation System to achieve three leaps: from nonexistence to existence, from active to passive, and from regional to global.

　BeiDou-1 Opens a New Chapter

In January 1994, BeiDou-1 was officially approved, and China began building an independent BeiDou Satellite Navigation System.

The first task assigned to the Xi'an Branch was the development of three satellites. The Xi'an Branch undertook the technical research and product development of the satellite payload system and tracking subsystem, including the development of the transponder subsystem, antenna subsystem, and tracking subsystem.

From the successful launch of the first BeiDou navigation test satellite to the fourth BeiDou navigation test satellite heading into space, during the development of the four satellites, the Xi'an Branch's development team accumulated and reserved a great deal of technology and system integration experience for subsequent missions, laying the foundation for the engineering implementation of BeiDou-2 satellites and subsequent missions.

　Multiple Technological Breakthroughs Help BeiDou Take Another Step Forward

The successful operation of the BeiDou-1 satellite navigation system made China the third country in the world to possess an independent navigation and positioning system. At the same time, the strategic goal of achieving regional networking and providing global navigation and positioning functions for the BeiDou Satellite Navigation System urgently needed to be realized.

In September 2004, the BeiDou-2 satellite navigation system was officially approved. The Xi'an Branch undertook the development tasks for all satellite navigation subsystems and antenna subsystems of BeiDou-2. Not long before that, the institute's early-arranged development of satellite payloads such as spaceborne rubidium clocks, precision spread-spectrum ranging, and navigation information processing had successively achieved breakthrough progress.

At that time, as China's new-generation navigation system, the navigation project as a whole faced difficulties such as achieving high-precision indicators and improving anti-jamming capabilities. Accordingly, the technology of the satellite payload system faced breakthroughs in multiple key technologies represented by high-stability spaceborne atomic clock technology, spaceborne precision ranging technology, and continuous and stable navigation signal generation technology.

Among them, the rubidium atomic clock is called the "heart" of navigation satellites in the industry, and the time reference it provides will directly affect the functions and performance of navigation satellites. After joint research by multiple units and fierce competition, the Xi'an Branch's development team successfully delivered more than 30 flight-model spaceborne rubidium clocks, achieving perfect on-orbit performance.

In April 2007, the first BeiDou navigation satellite was launched into orbit. The satellite completed not only the on-orbit verification of payload technologies such as domestically produced rubidium clocks and navigation signal design, but also the important tasks of seizing frequency resources, exploring the orbital electromagnetic environment, and establishing the flight-model state.

In October 2012, the construction of China's BeiDou-2 satellite navigation constellation was successfully completed, and it began providing satellite navigation services to the Asia-Pacific region.

　The "BeiDou Network" Covers the Globe

The space segment of the BeiDou-3 global satellite navigation system consists of 30 networking satellites. The Xi'an Branch undertook the development tasks for all payloads of 20 of them, as well as incremental payloads such as global short-message communication and search and rescue.

In March 2020, the 54th BeiDou navigation satellite was successfully launched. The Xi'an Branch provided payload products such as the navigation subsystem, antenna subsystem, and transponder subsystem for the satellite, helping the BeiDou-3 global satellite navigation system networking reach a "match point."

In the same year, the BeiDou-3 global satellite navigation system was officially opened. It can provide high-precision, highly reliable positioning, navigation, and timing services to various users worldwide around the clock and in all weather conditions, and has a unique short-message communication function.

After the completion of the BeiDou-3 global satellite navigation system, the spaceborne rubidium atomic clocks developed by the Xi'an Branch achieved an accuracy of one second deviation in three million years, and its navigation service capability is at the world's advanced level. In 2023, three BeiDou-3 supplementary satellites were launched successively, and the Xi'an Branch participated in the development tasks for all payloads.

Sun Jiadong, the first chief designer of China's BeiDou Satellite Navigation System project, once praised the Xi'an Branch's development team as having "great potential." After three decades, both the Xi'an Branch and China's BeiDou have step by step turned from "great potential" into "great achievements." In the future, the road of continuing to build a more integrated and intelligent BeiDou global satellite navigation system will never stop.