Is there a way to get X or S class Rocket launcher upgrades for your ship?

I can’t for the life of me find any

I stupidly visited the center for the first time after selling all of my ships since they couldnt compare to the new sentinel ships. I had no idea what happens when you visit since i never had the jump range to even consider making the trip until last night, thought I’d get cool screenshots, now ive got broken gear and a useless lump of metal, since it breaks the brain, and requires a new brain to fix it, but Im stranded and unable to find a new one since the planet i respawned on has no corrupted sentinels on it. so yeah,tldr- dont go through the center in an interceptor, brain breaks, you break, you sit there unable to repair.

edit: Why did I sell all of my ship? Because In total i have 40h of playtime and never collected or made any good ones, so i got the sentinel and planned to get more, so why keep the trash around when the new shiny is just around the corner.
Also ty, i had no idea about difficulty changing or free repairs, I bought the game when it came out and only recently started putting in decent play time, so there are a lot of features im cluesless on. Ty for the repair kit tips as well, I’ll be stocking up on those later this evening!