I liked it. It's a very well written piece of work, and the setting in Cardassia's past is certainly something I haven't seen before.
Certainly the relatively short time it took them to land on another world seems plausible enough given the quantum leaps made by our own space programs throughout the 1960s.
Imagine if that rate of progression had continued throughout the 1970s and 1980s? A landing on Mars a few decades after landing on the Moon seem to be unfeasible given those circumstances.
Overall a nice piece of work.