are telescopes in space impossible due to something?

I'll go with this one. :)
Yes, they are possible. Very expensive but we gather so much information with them, not even comparable to earth's observation.

You need to distinct different "types" of the light (depending on energy we use different methods to observe - gamma, X-ray, visible, infrared, radio). Atmosphere blocks most of the gamma and x-ray radiation and we have may X-ray telescopes already operating in space. Visible and radio things are pretty observable from earth too, but as you know we have Hubble Space Telescope and Kepler, and for radio we have less known Russian interferometry radio spektr-R telescope.
Revolutionary stuff that is awaiting a GO is James Webb Space Telescope, here is a video about it youtube link.
And images of all telescopes and the part of wavelength they observe - photo.

So, to cut it short - yes they are available, but they cost a lot. Luckily some people think that it is important enough to understand physics instead of spending money on guns. :)