ESA GNC Conference Papers Repository

Modern satellite missions require a flexible platform covering a wide range of missions from small to large satellites, optical to radar instruments with precise pointing performance or agility needs, for institutional and commercial customers. This flexibility is key, not only to allow for efficient re-use of existing architectures, but also to enable efficient adaptations instead of instantiating several rigid product lines with different solutions to maintain. In the context of Europe’s Copernicus missions, a common platform has been established based on the AstroBus standard developed by Airbus Defence and Space. The newest evolution, called the AstroBus Neo platform, complies with latest operational standards and state-of-the art AOCS architectures and algorithms, which makes use of modular building blocks and well established processes for avionics development. This paper will present the AstroBus mission perimeter, the AOCS architecture and indicate the modular approach and associated processes. It demonstrates mission capabilities in terms of orbit range, mode architecture and equipment architecture. The key elements of the AstroBus product are its modularity and its sophisticated tool chain, the Functional AOCS Multipurpose Environment (FAME). It is implemented in Matlab/Simulink. Depending on the mission dependant needs, equipment and AOCS related functionalities can be selected from a product catalogue. It is used to automatically generate a project specific instantiation of the AOCS algorithm and its associated simulation environment. Based on the project instantiation, which is embedded within FAME, the C-code of the AOCS algorithm can be automatically generated from the Matlab/Simulink implementation and directly integrated in the Central Software. Items needed by Functional Verification and Data Base, e. g. parameter files for the real-time simulator, software and operations related documents, are also included in the Auto-Coding process. Quality is ensured by applying automatic check routines already during early implementation phase. Results of the checks and the maturity status of the algorithms can be automatically documented and reported to the quality assurance engineer. The FAME also includes a tool chain to generate test documentation for functional and performance verification. Due to the high level of automation, the effort to perform deliveries to other disciplines is very limited, which makes the process perfectly suitable for agile development. Furthermore, the environment and the process allows a high level of flexibility to react on special project specific needs. Improvements made in projects flow back to the product such that other project can profit. The process also allows incremental deliveries. Another advantage of the high level of automation is a stable quality and reliability of all deliverable items. AstroBus Neo is the backbone for the common platform development in the frame of the ESA Copernicus missions CRISTAL and LSTM. The satellites have a distinctive difference in satellite shape, mass and orbit, driven by two completely different instrument types and performance needs. Nevertheless they share a large common core in terms of AOCS operations and algorithms in order that they can be operated with the same look and feel from Ground. The common core is enhanced by specific building blocks from the AstroBus Neo catalogue, e.g. to satisfy (dedicated) attitude performance needs by enhanced filtering algorithms and an unconditional live pointing antenna pointing mechanism guidance on LSTM, or a dedicated Earth Pointing Safe Mode Option for CRISTAL to cope with a drifting orbit. Upcoming missions demand for target-based observations with high resolution sensors and usually smaller fields of views. This requires fast platform attitude changes towards and during data-takes: The steering of body-fixed instruments (e.g. radar or optical) on specific attitude trajectories during data-takes and slews of minimal duration in-between emerges imposes a whole set of additional requirements on the product. The modularity of the AstroBus Neo product enables the native extension of the existing mode-diagram to agile missions, maintaining the existing capabilities of the product catalogue for non-agile operation, like station keeping or safe-mode options. The agile extension of the AstroBus Neo product will be generic and usable for different types of steerings, slew methods, actuators and their configurations.