Nice game! While playing I came up with some suggestions:
1. I would like to know the dimensions of the modules. For example, 1x1 for the small hub, 1x2 for the normal tanks, 1x3 for large, etc. This helps on the planning phase.
2. I would also like to know what modules do I unlock on the technologies menu. This would help set a goal for the next run / planning the upgrades to take.
3. There isn't enough information about what consumes what. Especially about power, tools and safety. It makes planning ahead almost impossible.
4. A way to activate/deactivate modules. Some modules consume power, even if they have no inputs / full storage. I feel this type of micromanaging is necessary.
5. A 1x3 solar panel. This adds some variety in the same way large tubes do.
6. Save the sound settings and tone down the failure sound. It kills me every time.
And this are more of a game changer:
1. Allow to move structures around. At the ISS they do it all the time. Just ask the player to have clearance on both the current airlock and the target one. Can even make it a 2 day process (and reuse the code for launched modules).
2. Separate the structural part from the functional part. With this, you allow the player more flexibility at the time of building the station. It also allows for cheaper construction costs / planning expansion. Think of the tubes as Bungalow modules (the inflatable ones).
3. As for the cost of the modules, use a generic resource, like supplies. And use it in favor of tools and safety for maintenance cost (makes it more intuitive). Can make assembly/dismantling a 1 day process.
4. In order to not make supplies from the vacuum, how about adding something like taking shipments of raw materials from some mining station.
5. Separate launches by type and/or allow multiple launches per day. Nowadays, it's not rare for multiples launches to happen across the globe.
Well, that will be all for now. Hopping to see the next version!