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Satellite control systems
How do you monitor and control the health of satellites carrying out missions in space?Satellites carry out missions far from Earth, in the vastness of space. Monitoring and controlling their health from the ground is essential for the completion of these missions. For example, the Hayabusa satellite collected samples from the asteroid Itokawa and backed to Earth after a seven-year journey. How do we know the status and send commands to satellites that are so far away?
Satellite control systems monitor and control satellites from Earth
The task of monitoring and controlling the health of satellites operating in space is carried out by satellite control systems at ground-based control centers. Each satellite has a dedicated satellite control system in place to manage its operations, whether for communication, navigation, Earth observation, or other purposes.
The satellite control system monitors satellites through ground stations on Earth. Using antennas at these ground stations, it communicates with the satellites via digital signals to check their position and health status. As needed, it adjusts the satellite's orbit or attitude and gives instructions for missions, such as taking photographs. This ensures that the satellites are correctly positioned and can fulfill their intended purposes. All communications are encrypted to ensure security.
Operation of ASNARO-2 high-resolution small radar satellite developed by NEC
Satellite control operations consist of mission planning, satellite monitoring and control, and orbital mechanics calculations.
- Mission planning
Based on the objectives of the satellite, mission planning involves automatic generation of control plans and optimization while considering constraints to create a detailed operation plan. This process utilizes requirements analysis, simulation, and scheduling technologies. - Satellite monitoring and control
Satellite data collection and analysis, anomaly detection, and control signal transmission are performed in order to maintain the stable operation of the satellite. This process utilizes real-time processing, failure mode analysis, and automatic control technologies. - Orbital mechanics calculations
Orbit determination, orbit prediction, and orbit control are performed in order to maintain the satellite in its designated orbit. This process utilizes the least squares method, Kalman filter estimation algorithm, mechanical model calculation, and disturbance modeling technologies.
Through the above processes, satellite operations are carried out continuously in accordance with a detailed operation plan while conducting precise orbit calculations and checking the data sent from the satellite.
How do we communicate with satellites from Earth?
For example, during Hayabusa’s rendezvous before landing on Itokawa, it was about 300 million km away from Earth. How do we know what's going on with satellites at unimaginable distances away?
NEC’s wide array of communication technologies play an active role in long-distance communication with satellites.
- Radar technology
Use of radio waves that can be used with very weak strength of a few milliwatts - Information compression technology
Compression of fine image data to reduce the amount of data for transmission - Error correction technology
Detection and correction of errors in communication data caused by radio wave attenuation and signal alteration
Contribution to the safety and security of society by achieving stable operation of satellites
Satellite control systems require highly advanced technological capabilities. NEC has been responsible for the development of many satellite control systems, including those of the climate change observation satellite Shikisai, the quasi-zenith satellite Michibiki, and the Japanese Experiment Module Kibō on the International Space Station. NEC is able to continuously develop technology and accumulate operational experience, as well as introduce its specialty IT technologies into system development.
NEC is engaged in research and development of satellite control systems to ensure the stable operation of satellites and to respond to disasters and other emergencies, utilizing its years of accumulated knowledge in space development. Looking to the future, we aim to introduce AI and other cutting-edge technologies to increase speed and streamline manpower in consideration of social issues. NEC will contribute to the safety and security of society by realizing the stable operation of satellites as critical infrastructure.