True, could have been erosion and ocean currents wearing them down as well.

The inside of the tiles is pretty much a foam like texture (extremely porous), except it's hard and made out of silica. And then they would add either a white or a hard black coating on the outside

The tiles are white on the inside, and these tiles look pretty clearly like the tops were ripped off. You can also see bits of black on the sides of some of the tiles that are still there.

Can you not? Cut it out with the conspiracy crap. As someone who works on the space program, I'm tired of hearing all the anti NASA peanut gallery comments that just assume some weird political corruption is going on behind the scenes, and that that is the only reason the architecture was planned how it was. It's very far removed from reality but yet that conspiracy garbage is something me and my coworkers get spammed with practically every time we talk about work on social media.

Also you should read that r/science comment you linked as a source more closely because it mentions practical reasons why segmenting makes sense and actually supports what I said moreso than you.

I mean, redundancy and fault tolerance aren't absolutely mandatory for a design to be good, as long as it's a simple design used in design operating conditions with a low chance of failing. SRBs flown pre-STS-51L in design temps didn't have signs of burn through, only ones flown cold showed signs (which the fact those flown out of spec showed signs even before 51L should have set off alarm bells and gotten the situation resolved without loss of life)

But yes, it definitely was made a better design by adding that fault tolerance, and without adding too terribly much mass and complexity. And it makes sense that they'd add it in after experiencing that failure mode (even if it was caused by out of spec operation) just to give more peace of mind.

They need O-rings to seal the joints because the SRBs of that massive size are made by stacking multiple segments together and you need to be able to seal the hot gasses inside between the joints. There's no practical way to make SRBs that big without splitting them into segments

It wouldn't have been an issue if they used them at the correct temperatures. Though to be extra safe, they also redesigned the joints to be more robust and have a second layer after the failure. That redesign + more strict rules on launch temperatures led to there never being another issue with that part of the booster.

The design wasn't bad, if it was used properly in the correct environment. The way they were using it is what was bad, because it wasn't designed to be used at those temperatures and they knew it but ignored the spec. And using stuff outside of spec without any kind of analysis nor investigation to confirm it won't be a problem is a lesson they learned in blood. It's something still taught to the current NASA work force (which I'm part of).

Not under the doors, but the very bottom of the vehicle. The belly of the vehicle was covered in square shaped tiles and a relatively flat shape, which matches the piece that they found.

Under the doors were radiators, and the doors for the most part had no tiles on them