>>1474924>It lived out its expected service life.Five orbiters were built. Each orbiter had an expected service life of 100 missions. 5 times 100 is 500. 135 is nowhere near 500.
>Then why wasn't it cancelled after a decade?Two decades?See
>>1474917, the second part
The loss of Challenger arguably helped the shuttle, as it made getting back into space (via Shuttle) a national conviction.
The ISS also was roped into the justifications for the program, as cancelling the ISS would have diplomatic repercussions.
Parts of the program, like the manufacture of the reusable engines which are now going to be tossed into the ocean, continue to this day, for jobs purposes.
>Yes it is.No it isn't. Same reason why everyone doesn't upgrade to the latest model of anything as soon as it comes out. The process of getting funding to research and develop the Shuttle was prolonged and torturous, and led directly to many of its faults; they originally wanted liquid boosters, as an example. Any attempts at replacements would face the same problem. Even today, nine years after the final flight, the US has no manned spaceflight capability, with Congress consistently underfunding the Commercial Crew Program.
