Following STS-51-L (i.e., the Space Shuttle flight on which Challenger exploded on ascent), the Space Shuttle fleet was grounded for a bit over two-and-a-half y

Following STS-51-L (i.e., the Space Shuttle flight on which Challenger exploded on ascent), the Space Shuttle fleet was grounded for a bit over two-and-a-half years. This is quick (OTOH, this is unmanned!). After the Ariane 5 first-launch failure, it was well over a year before it flew again.