Xi’an Satellite Control Centre
The Xi’an Satellite Control Centre (XSCC), or Base 26 in its military designator, is the communication hub, command and control centre, data processing centre, and administrative headquarters of China’s space telemetry, tracking, and command (TT&C) network. The centre supports China’s space missions through a network of land-based tracking stations located both within China and overseas, a fleet of tracking ships, and tracking & data relay satellites (TDRS) stationed in geostationary Earth orbit.
The XSCC was created on 23 June 1967 as the “Central Control & Processing Station” of the Jiuquan Satellite Launch Centre to support the launch of China’s first artificial Earth satellite (Project 651). The station was then relocated to Weinan, Shaanxi Province in January 1968. With the assistance of the China Academy of Science and directions of top Chinese scientists Wang Daheng and Chen Fangyun, the construction of the mono-pulse and Doppler radar facilities was completed in 1970.
On 24 April 1970, China’s first satellite Dong Fang Hong 1 was lofted into orbit by a CZ-1 launch vehicle lifting off from Jiuquan. The Central Station in Weinan was given the task of forecasting the satellite’s orbit and collating its flight parameters. The station’s radar captured the satellite five minutes after the launch. The separation of the satellite from the launch vehicle was reported as it occurred. As the satellite entered the horizons of the station again after orbiting the Earth, the station captured the satellite’s flying path and calculated the time at which the satellite would pass 244 cities around the world.
In the mid-1970s, the Weinan Central Station was added with a number of forward-positioned radar stations, mobile TT&C stations, and the recovery station to support the FSW recoverable satellite missions. Several missile tracking stations originally built for ballistic missile tests were also reassigned to the Weinan Central Station to expand its coverage. Since then, the central station served as the nerve centre and mission control for Chinese satellite launch missions in the 1970s and 80s.
In March 1988, the central station was relocated from Weinan to Xi’an, and was renamed “Xi’an Satellite Control Centre”. The centre also received extensive modernisation upgrade in order to support the launch of geostationary communications satellites (Project 331). From 1999, the XSCC has also been serving as the backup mission control centre for China’s human spaceflight missions.
The control centre operates 7 main systems:
Tracking and telemetry system – By using radio tracking and telemetry equipment onboard the spacecraft to acquire its motion parameters, including altitude, orientation angle, pitch angle, distance variation rate, etc. in order to calculate the spacecraft’s orbital root numbers.
Telemetry system – By using onboard radio telemetry equipment to receive the spacecraft’s engineering parameters.
Remote control system – To issue remote control commands to the spacecraft to control its flight
Data processing system – Computer systems to process the spacecraft data
Communication system – Cable and wireless communications with the mission control, launch sites, and TT&C stations and ships.
Time frequency system – Synchronising network time to the radio clock of the Shaanxi Astronomical Observatory
Command and control system – Command and control of the entire TT&C network.