China successfully launched two navigation satellites with one rocket. Beidou 3 signified a strategic initiation of Beidou’s global network

At 19:45 on November 5th, China successfully launched the first and second navigation satellites of BeiDou 3 into space with Changzheng-3B carrier rocket in Xichang Satellite Launch Center. This is China's first launch since the 19th National Congress of the Communist Party of China, signifying a strategic initiation of BeiDou navigation satellite system's global network.

The capacity of the global network can rival that of GPS

It is one of the 16 main projects of China's medium and long-term development program in science and technology filed to construct highly qualified and reliable BeiDou global navigation satellite system. When complemented, the capacity of the system can rival that of GPS, drawing China's navigation satellite system up towards the internationally advanced level.

Yang Changfeng, chief designer of BeiDou, introduced, "From 2015 to 2016, we have launched 5 experimental satellites of BeiDou 3 step by step, to test new technology and new system as well as solidify the techniques. The successful launch of BeiDou 3 navigation satellite signifies that BeiDou system has stepped into an era of global BeiDou coverage, ushering a new situation of technique promotion and industrial development, opening up a new chapter of international cooperation." Yang also introduced that these two satellites in Medium Earth Orbit, are the 24th and 25th BeiDou navigation satellites China has launched. After the satellites are sent into orbit, relevant tests and verification will be conducted and global service will open at proper time.

Compared with BeiDou 2, BeiDou 3 will be equipped with better qualified signal B1C which is more compatible with other navigation satellite system around the world. BeiDou 3 also provides Satellite-Based Augmentation System (SBAS) and Search and Rescue (SAR) in accordance with international standards. Meanwhile, BeiDou3 uses high performance rubidium atomic clock and hydrogen atomic clock, with the stability of E-14 and E-15 respectively. "New techniques upgrade the performance of BeiDou 3 to a higher level, with its Signal in Space (SIS) outperforming 0.5m. BeiDou 3 will be equipped with better qualified signal B1C which is more compatible with other navigation satellite system around the world. We plan to issue the official version of Interface Control Document (ICD) in response to the operation of these two satellites." said Yang Changfen.

Xie Jun, deputy chief designer of BeiDou 3 project at the 5th Institute in China Aerospace Science and Technology Corporation and chief designer of the satellite, introduced, "BeiDou system is moving towards the goal of serving globally at full speed. Compared with that of BeiDou 2, the coverage of BeiDou 3 will be expanded to the whole world. Meanwhile, breakthrough has been made in upgrading and reforming downward navigation signals. Transiting smoothly from BeiDou 2, BeiDou 3 is equipped with new navigation signals and will offer qualified service for its users."

Chi Jun, chief commander of BeiDou 3 at the 5th Institute in China Aerospace Science and Technology Corporation, introduced, "BeiDou is an open system. It belongs to China as well as the whole world. It serves as the important infrastructure of national economy as well as provides temporal and spacial coordinate for the whole world." BeiDou has been influencing human's life like water and electricity, which poses strict demands for the reliability and continuity of BeiDou navigation. Through various reliable measures, the life span of BeiDou 3 satellites can be expanded to more than 10 years.

BeiDou is on the way to serve countries along Belt and Road, such as the agriculture, forestry and land planning in Myanmar, precision agriculture, the detection and management of pests and diseases in Laos and smart tourism in Brunei. Up till now, BeiDou system has covered nearly 30 countries along Belt and Road, including Pakistan, Saudi Arabia and Myanmar.

Satellites in Medium-Earth orbit (MEO) are set to be launched firstly in project strategies for BeiDou 3. With the accelerating construction of BeiDou global system, it will first cover the countries and regions along Belt and Road, serving them with more accurate service.

New BeiDou is more flexible, accurate and reliable.

Where the difficulty lies in setting global network compared with setting a domestic one?

Xie Jun said that difficulties come with restrictions on setting up ground stations in other countries. In consequence, engineers conquered technical problems and built up Crosslink which communicates satellite with satellite, satellite with ground station. That is to say, although the BeiDou satellite at the other side of the Earth is invisible, Crosslink can connect them together. Crosslink technology makes the communication and date transmission among BeiDou satellites possible. It can also detect the distance of satellites and maintain their formation, relieving the governance and management stress on the ground.

Xie Jun said that BeiDou 3 designed new network protocol, management strategy and routing strategy, resolving the problem that ground stations cannot be set up across the globe to enable satellites to conduct oversea monitoring. This is one characteristic in the construction of BeiDou global navigation satellite system.

In addition, satellite-loaded atomic clock is the key equipment to ensure accurate position. Wang Ping, chief designer at the 5th Institute in China Aerospace Science and Technology Corporation, said that BeiDou 3 is equipped with the latest rubidium atomic clock and hydrogen atomic clock. It aims to improve satellite capacity and user experience through raising the indicators of atomic clocks.

In the meanwhile, the subsystem of BeiDou 3 on satellite control ensures that the satellite can operate independently for at least 60 days. Even when the ground and control stations break down for a while, BeiDou satellite can normally work in orbit. In addition, the life span of BeiDou 3 satellite are expand to more than 10 years, which reaches advanced level of international navigation satellite, to ensure the continuity and stability of the service.

Blueprint: to construct a temporal and spacial information-serving system in an all-round way

According to the plan, China will launch 18 BeiDou satellites in 2018, constituting a satellite network and covering countries along Belt and Road. More than 30 satellites will be launched around 2020 to provide global service. At the moment, BeiDou is moving towards this goal at full speed, going globally in leaps and bounds.

Yang Changfen said, "BeiDou navigation satellite system is China's important spacial infrastructure. China will steadfastly keep constructing BeiDou system, upgrading its capacity and fulfill our service commitment."

He also introduced, when constructing BeiDou 3 in the new area, the developmental blueprint of BeiDou also includes the construction of comprehensive PNT system (positioning, navigation and timing). Centering on BeiDou system, the comprehensive PNT system will integrate space and ground services (including space, ground, undersea and indoor) and realize seamless coverage, being safe, reliable, effective and convenient. The achievements will improve China's temporal and spacial information-serving capacity, meet the needs of national safety and national economy and provide qualified service for global users.

The launched BeiDou navigation satellite and carrier rocket set are developed and manufactured respectively by China Academy of Space Technology and China Academy of Launch Vehicle Technology affiliated to China Aerospace Science and Technology Corporation. This marks the 253rd flight of Changzheng serial carrier rockets.