The primary objective of the CubeSat Command Module development is to create a command module that is capable of running AI models, and additionally features a software-defined radio (SDR) for use in nano- and micro-form-factor CubeSats.
With further development, this prototype could be deployed not only in future Student Satellite CubeSat platforms but also in the hundreds of CubeSats launched into orbit each year. The command module’s software-defined-radio functionality would provide a high performance communication link to Earth. Meanwhile, the high-performance onboard computer shall enable the use of state-of-the-art machine learning and artificial intelligence algorithms, significantly increasing spacecraft autonomy.
The main subsystems of the command module are:
– The Communications Subsystem (COM): A software-defined radio with RF front-end circuitry capable of receiving and transmitting; the analogue radio signal is created and received by the RF SoC DAC and ADC peripherals.
– The Command and Data Handling Subsystem (CDHS): A system-on-a-chip-based module capable of running an embedded Linux operating system and executing AI algorithms for spacecraft operations.
– The Electrical Power Subsystem (EPS): A power supply system capable of supporting the Radio Frequency (RF) frontend and an RF system-on-a-chip (SoC) based CDHS system.
The command module that is being developed differs from the usual spacecraft avionics stack in that it shall not include an ADCS, nor an EPS capable of supplying the entire platform, as both are scaled per mission. The EPS that will be built into the module is for the module itself, not the entire satellite. The command module shall not have a radio power amplifier, but it shall be able to interface with an external amplifier. The amount of power amplification that is needed depends on the mission, and it will be adjustable to suit each mission or craft.
Command Module Subsystems
Radio Communications Subsystem
The first objective of the project is to develop a radio communication circuit essential for the operation of the software-defined radio. This circuit comprises three logical components:
– Modules for up- and down-conversion of the radio signal,
– An RFSoC that incorporates high-sample-rate analogue-to-digital and digital-to-analogue converters (ADC and DAC),
– And a precise oscillator serving as a reference signal for the system.
The CDHS and COM subsystems are physically located within the same SoC and share some resources. When the COM subsystem is idling, i.e. waiting for a telecommand, the resources are allocated for the spacecraft’s autonomous operations and vice versa.
Command and Data Handling Subsystem
Modern satellite command and data handling systems (CDHS) typically lack the computing power to run complex data processing or error-detection algorithms, which are capabilities essential for autonomous deep-space operations. Instead, most deep-space missions rely on the International Deep Space Network (DSN) for command and navigation. However, the DSN is becoming increasingly congested with missions from major space agencies, and there are currently no scalable technical solutions to manage the rising demand. To address this challenge, the second objective of the project is to integrate a capable system-on-a-chip into the control module. This SoC serves as the satellite’s onboard computer, enhancing its autonomy.
Electrical Power Subsystem
The third goal of the project is to develop a robust power supply system for the control module that ensures continuous operation even under the harsh environmental conditions of space. This system must provide sufficient and stable power to the radio circuit, transceiver, and computing module. Additionally, it must be efficient, reliable, and capable of monitoring power consumption across components, with built-in safeguards to interrupt the circuit in case of excessive load or other faults.
The CubeSat Command Module that will be built will consist of three main subsystems, the electrical power subsystem, the command and data handling subsystem, and the communications subsystem. The command module is designed to power itself and be able to function by itself, leaving external parts to be scalable for each mission and satellite so the Command Module can be produced for a large variety of CubeSats and utilized by everyone, not just the Estonian Student Satellite Foundation.
Make sure to keep an eye on our upcoming blog posts where we will be diving deeper into our Command Module development and the many different aspects of it. Next month we will be covering the hardware architecture of a CubeSat command module.
Once again big thank you to the Command Module development teams for the text and assistance!
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