Here’s some more context on what we’re trying to accomplish. This is a report to the payload team about the system definition work for the payload project, and is why I reached out about the UPSat ADAC work.
Thomas Parry has drafted a top-level system definition of our open source satellite design.
It’s located here:
He’s modeling the system using a model-based system engineering approach. He uses an open source tool called Capella developed by Thales.
This is a sustainable and extensible modeling workbench that allows motivated people to master architectural design and manage complexity.
He has wanted to give this method a go for a while now as it gets good reviews. He believes it will be useful for this project as it attempts to keep the system definition in centralized model in order to avoid the quagmire of documents and fragments of documents which become inaccurate over time.
A very nice feature? It renders to HTML pages, you can see the intro page here https://phase4space.github.io/system-definition/capella-system-models/top-level/HTML/output/top-level/index.html
Thomas has some initial high level requirements. What are the others? We need to work here to weigh and consider what we need to include.
The process of creating this document will move from system needs analysis to a logical architecture analysis and then finally to the low level definition of the physical architecture.
Thomas has also been working on some power simulations. You can see this documented here:
He has developed some scripts that allow us to perform detailed power modeling with accurate orbital analysis, solar panel configuration, load power specification and battery size.
This also includes things such as solar cell radiation degradation, battery cycle fatigue and load TID induced power increase.
The current numbers need to be vetted. But, now the tool is there it will be very quick to plug in improved numbers and iterate as we proceed.
Thomas has looked the TID (Total Ionizing Dose) we can expect on orbit versus shielding thickness. This gives a starting point for scoping radiation tolerance and mechanical design
Going forward, the main things Thomas has in mind are:
- progressing into detailed system modeling
- obtaining some numbers on propulsion
- link budget - this has a large impact on the power budget for the PA and physical arrangement of the spacecraft
We need to support Thomas as he drills down into the detail over the next month to get to the subsystem level. We need to get a first pass mapping of interfaces like xdsopl (Ahmet) recently mentioned.
This system description framework allows us to see the areas that we need to focus on to start pulling it all together.