I often wonder how come we(as in, humanity) ever only launched a single Hubble telescope. Surely, once you built one, you should be able to build more. Or other countries should be able to take the designs and launch their own versions. Hubble was(and I imagine still is) occupied for weeks at the time taking pictures of certain areas of the sky. Why don't we have 50 Hubbles up in the orbit, doing different things simultaneously? Is it simply because there's no money to do so?

I also do remember the story how NASA got a couple decommissioned telescopes from some intelligence agency, which turned out to be an order of magnitude better than Hubble is, and the agency was getting rid of them because they were already outdated. I do remember reading that if those were put into astronomy use they would be a lot better than anything we have currently, but of course those are being used for taking pictures of military sites and tanks, rather than stars.