China launched two BDS satellites via one single Long March-3B launch vehicle from Xichang Satellite Launch Center, at around 19:45 Beijing Time on November 5, 2017. The 24th and 25th BeiDou satellites, which will be operating on a medium-Earth circular orbit, are the first and second BDS networking satellites, and opened up a new era of the global deployment of the BeiDou Navigation Satellite System (BDS).
After satellites are inserted into the orbit, they will start providing services after in-orbit tests and operational validation are completed. The launch of the BDS global networking satellites will steadily promote the construction of the BDS-3 system and accelerate the earliest BDS adoption to serve the world and to benefit all human being.
The development of the BDS-3 Project started officially in 2009. With the joint efforts of the major subsystem developers and many participating research institutions and companies, China has completely broken through key system technologies and completed ground verification. The state of satellites has been basically solidified, and in particular, five new-generation navigation satellite were successfully launched from 2015 to 2016, with which on-orbit verification were conducted..
The BDS-3 satellites are equipped with performance-optimized B1C and B2a, which will be interoperable with their counterparts from other GNSS systems. Further enhancement of the basic services, such as Satellite-Based Augmentation System (SBAS) and Search and Rescue (SAR) services, will be provided according to international standards. Meanwhile, BD-3 will adopt the higher-performance rubidium atomic clock with stability of E-14 and hydrogen atomic clock with stability of E-15. By utilizing new technologies, the performance will be greatly improved, and the signal-in-space (SIS) accuracy will be superior to 0.5m. Comparing with the BDS-2’s performance, the BDS-3’s position accuracy will be enhanced 2-4 times, reaching 2.5 to 5 meters. On the premise of retaining the BeiDou-2 system’s short message communication services, the relevant performance has been improved.
From this mission on, China has ushered in a new round of high-density launches of the BDS networking satellites. The goal is to provide basic services to the countries along the Belt and Road and in neighboring regions by 2018, and to complete the constellation deployment with the launching of more than 30 satellites by 2020 to provide services to global users.
The BDS Satellites and the launch vehicle in this mission are developed by China Academy of Space Technology and China Academy of Launch Vehicle Technology, respectively, both academies are subsidiaries of China Aerospace Science and Technology Corporation. This launch is the 253rd flight of the Long March family.