Thank you!
I implemented the upgrade system to work off an .ini file, so adding the core parts of an upgrade isn't too hard. (Yay "data driven". XD) The main limitations for me was implementing the changes to the rocket graphically (I'm not a great artist), and the fact I didn't want to drag it out too long and make it boring, since the gathering mechanic was so simple and a bit tedious
I actually wanted to have a whole other mechanic where you got parts from the junkpiles after clearing them fully. You would then click on the rocket to open an interior UI where you could do a minor repair on each part before slotting them in. So solar panels could have been a thing there.