|The stylish but expensive orbiter|
The shuttle is also notorious for launch delays. There are simply too many valves, sensors, and seals that can fail, and NASA won't launch if any of them do. This is to say nothing, of course, of the years the shuttles were completely grounded. They didn't fly for 975 days after the loss of Challenger, and 907 days after Columbia. We should consider the Space Shuttle's cost and schedule performance before committing to any similar launch scheme.