[frederikvs]

I'm not familiar enough with the project to answer why specifically cold gas thrusters were chosen. What I can say : if old, proven technology will get the job done, there's a strong preference to use that.

When needed to achieve the mission, new technology will be developed - sometimes the whole point of a mission is specifically to develop new technology. In this case, one of the major goals of the mission is to develop formation flying technology. Learn what the pitfalls and the tricky bits are, and make the technology available for future missions.

But when the mission can be achieved with old technology - technology with a long record of being used in space, where the problems are known and understood, where we know what works and what causes problems - then the mission will use old technology.

If you use newer technology, there's always a risk that you'll hit a new issue, previously unknown. Maybe you can work around it, maybe you can't. But this isn't web development where you can refactor, switch to a new framework and continuous deploy your way out of it. For the hardware, you get one launch and that's it. Why run the risk if you can avoid it? It'd be a shame if the mission can't achieve its primary objective (learning about formation flying) because it chose some new type of thruster, and encountered some new issue with it.

[nuccy]

Cold gas thrusters are as reliable (because of simplicity - basically just container of pressurised gas and a valve [1]) and as precise in their thrust pulses execution as it can get. Better precision in thrust execution probably only ion engines have but just because of extremely low thrust levels in general (milli-newtons).

1. https://en.m.wikipedia.org/wiki/Cold_gas_thruster

[pests]

I saw a really good YT video a few months ago that explained this very well. Went over all the fuel types and tanks and propulsion designs.

Started with what you said - a simple gas pressurized and a single valve.

Slowly more and more was added until we get to current rocket designs with multiple stages or active pressurization / fuel transfer and all that entails.

Wish I could find it again.