TWO shuttles blew up. Challenger and Columbia. IIRC, Challenger's problem was brittle O-rings on the external rockets (Morton Thiokol) and Columbia suffered a tile loss on lift off when a piece of foam broke off the boosters. The hole in the wing caused a breakup on reentry.
I remember when the Shuttle was first proposed. They were touting dozens of flights per year with 3-5 day turnaround time to get ready for the next launch. Boy, we were sold a bill of goods on that one. After the crashes, NASA retreated into its test, test, test, document, document, document, oversight, oversight, oversight sand hill which resulted in massively increased prices for anything it did or contracted out. It's one of the reasons why a project I managed to design and build an ISS airlock handhold antenna ended up costing $1M (yes, I have something of mine orbiting the Earth - I also had a project experiment that flew on STS-44 and got to watch liftoff in the VIP stands across the marshes). Actual cost to build one antenna without all that mess was about $35K. Had to build 5 of them. One for proof of performance, two for destructive testing, and onefor flight with a backup. The rest was pure BS.
