I didn't realize there were varying degrees of "impossible". Is there such a thing as a little impossible? 
Actually, there are, though I wouldn't use the term "little impossible". I'll give an example: Direct sensing of atoms. The building of the first scanning tunneling microscope overcame two seeming "impossibles". First, it was thought that making an atomically sharp tip was impossible. It turned out that you don't need that sharp of a tip, as the tunneling current you want to observe is so tightly dependent on the distance between the tip's atoms and the atom's you are imaging, so in practice, one slightly "protruding" atom on the tip is good enough. The second problem was to eliminate vibrations, which was also thought to be impossible. However, the physicists solved this by using strings, dampers, and heavy masses. The result was awarded the Nobel prize in 1986.
This is an example of what was thought to be impossible. In fact, it would have been impossible before you could have built the electronics to drive the system. It would have also been impossible without the new engineering solutions in the vibration dampening. Nowadays, it's a standard technique for surface studies, along with several others derived from it (atomic force microscopy, magnetic force microscopy, and so on).
In short, there really are degrees in impossible.
