Two space shuttles exploded, killing everyone on board.
https://en.wikipedia.org/wiki/Space_Shuttle_Challenger_disas...
https://en.wikipedia.org/wiki/Space_Shuttle_Columbia_disaste...
https://en.wikipedia.org/wiki/Space_Shuttle_Challenger_disas...
https://en.wikipedia.org/wiki/Space_Shuttle_Columbia_disaste...
The Apollo flights in particular were interesting. For example, in the case of Apollo 14, when Houston was literally reading new machine code to the astronauts over radio who were punching in POKE instructions by hand to change the code.
And Challenger.
Every now and then we watch/read in the news that # of workers died while building that bridge/road/building/etc. We don't stop making bridges/roads/buildings. We just make it safer. Will people continue dying unnecessary/unnatural deaths? Unfortunately, yes. Let's minimise this.