Determining the best architecture for a satellite system is a challenging task, where numerous factors need to be taken into account. It is an inevitable gamble of compromise between ambitious mission objectives and natural constraints such as weight and size of subsystems, energy levels, and technical limitations.
The development of M6P multi-purpose nanosatellite bus (from the inception to assembling the parts) took a whole year plus invaluable multi-year experience from successful satellite missions and R&D projects. The goal was to create an advanced spacecraft which would be able to host a wide array of instruments of up to 5U in size, having high performance, and optionally enabling orbit synchronization (and others necessary for constellation functions) with its integrated green chemical propulsion subsystem. In addition, the bus had to have a sufficient energy supply, be comparatively low cost, perfectly reliable and low mass.
Putting it all together, the team has designed the architecture of the bus with the following subsystems:
- Flight Computer (3C2) combining the most crucial functions of the satellite bus:
- Attitude Determination and Control System – one of the most complicated subsystems of the whole bus with complex software processing data from the sensors: star tracker, inertial measurement unit, 6 sun sensors, GPS; and giving commands to the actuators: reaction wheels and magnetorquers. This subsystem checks the satellite’s position and angle several times per second and gives precise commands to the actuators.
- On-Board Computer – hosts the scenario of the mission, scheduling and executing scripts for the subsystems of the bus. It is responsible for the collection and logging of the mission data.
- EPS – the heart of a satellite, responsible for controlled supply, flow, and storage of energy for other subsystems and the mission’s payload. Fail-safe and highly efficient.
- Communications modules:
- Redundant UHF radio with omni-directional antenna dedicated to commissioning faze – foolproof subsystem which makes it less complicated to check the health of and set up the satellite for the mission right after deployment
- S-band radio – main communications unit dedicated to mission objectives and allowing transmission of big packets of data
- Payload Controller – a powerful computer dedicated to the customer’s payload only, allowing them to program desirable commands, mission tasks and scheduling for the payload.
- EPSS – green chemical propulsion subsystem with low energy consumption and high thrust levels. Prolongs the lifetime of a satellite and is necessary for synchronized constellations.
- Solar Panels
And, here’s an interesting fact – everything is fastened together using 438 bolts!
M6P development and current manufacturing process is strictly controlled based on NASA GEVS, ESA ECSS, and ISO 9001 standards, and involves rigorous documentation that registers every step of the process. High standards, but ones we must meet and exceed.