A Concept of Integrated Space-Based TT&C System
- Paper ID
IAF-96-U.5.01
- author
- company
China Satellite Launch and Tracking Control General
- country
China
- year
1996
- abstract
First of all , the current space-based TT&C system and space- based TT&C resources are briefly described, and the advantage of each system is analyzed in terms of its functionality and performance. Then, an integrated space- based TT&C system combining TDRSS and GPS systems to provide tracking, positioning and digital information transmission services for highly and low dynamic users both on ground and in space is proposed. Constellation of the system consists of two operational geostationary TDRS-type satellites and four to six highly- inclined elliptic GPS- type satellites, with the former providing TT&C services for spacecraft in medium and low earth orbit and repeating GPS- type signals. The two geostationary TDRS-type satellites and GPS- type satellites periodically forms a high accuracy optimum constellation over China, enabling it to measure high accuracy position and velocity of highly dynamic targets such as spacecraft launch vehicles. Increasing the rotating angle of the parabolic antennas on the TDRS- type satellites shall enable the system to cover the transfer orbit, and a large antenna aperture shall enable the system to transmit high data rate telemetry and command information for boost phase launch vehicles or to relay GPS tracking data at high bit rate. Besides, the proposed system shall also be able to provide excellent navigation and positioning services for terrestrial and near-space users in the China region. This shall greatly improve its utilization and cost-effectiveness while reducing or eliminating China's dependency on foreign satellite navigation systems. Finally, some technological areas critical to the establishment of the integrated space-based TT&C System and calling for further research and development are identified. The advantages and shortages of current space- based TT&C systems are analyzed. Then, a real integrated space- based TT&C system combining TDRSS and GPS is conceived taking advantage of successful technologies. However, there are still some difficulties with current technological level. Many system problems require further study , e. g. , optimum constellation, optimum orbit of GPS- type satellites (Molniya or Loopus) , high data rate transmission system, selection of system operational frequency bands, relative cost- effectiveness between the cost of extremely large aperture antenna on the satellite and multiple telemetry relay stations. Some breakthroughs are being made in some of the technologies, for example, space test of 14m inflatable satellite- borne antenna model shall be performed soon, both Japan and European space agency is experimenting with satellite-borne phase- arrayed antennas for future data relay satellites. Implementation of a concept or design depends mainly on the number of space missions in a certain period of time and their requirements on TT&.C (e. g. , coverage, data transmission rate and cost-effectiveness) besides its technical justification and feasibility. Therefore, for such an integrated space-based TT&-C system, combination of navigation, positioning and (mobile) communication must also be considered.