[Ground-station] Systems Definition Document - Phase 4 Space

[Michelle Thompson]

Thomas Parry has drafted a top-level system definition of our open source
satellite design.

It's located here:

https://github.com/phase4space/system-definition

He's modeling the system using a model-based system engineering approach.
He uses an open source tool called Capella developed by Thales.

https://www.polarsys.org/capella/features.html

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:

https://phase4space.github.io/system-definition/capella-system-models/top-level/HTML/output/top-level/index.html

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:

1) progressing into detailed system modeling
2) obtaining some numbers on propulsion
3) 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.

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What can you do to help?

Read, weigh, consider, reply.

This will happen with your participation and contribution.

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