EDIT: OMG! I just discovered that you can scroll the tech-tree horizontally.
I was going to say that by the time I had the Stellar Class that you have unlocked, I had the other classes as well, so I thought you probably haven't scrolled to the right. :D
It's okay though. I didn't look for the Araona Capital for hours until I accidentally found it. And then I noticed the search bar in the mission log section and that that's how I was supposed to look for information for the quests...
Anyway, for everyone else wondering, at some point when you talk to Lt. Chiang and he asks for some resources in order to expand the engineering section, so it can support bigger ships.