Question: If, when you drop a buttered piece of bread, it drops butter side down and a cat always lands on its feet. What would happen if you took a piece of buttered bread, strapped it on the back of a cat (butter side up) and dropped it?
Answer: Even if you are too lazy to do the experiment yourself you should be able to deduce the obvious result. The laws of butterology demand that the butter must hit the ground, and the equally strict laws of feline aerodynamics demand that the cat must land on it's feet. If the combined construct were to land, nature would have no way to resolve this paradox.
Therefore it simply does not fall.
That's right you clever mortal (well, as clever as a mortal can get), you have discovered the secret of antigravity! A buttered cat will, when released, quickly move to a height where the forces of cat-twisting and butter repulsion are in equilibrium. This equilibrium point can be modified by scraping off some of the butter, providing lift, or removing some of the cat's limbs, allowing descent.
Most of the civilized species of the Universe already use this principle to drive their ships while within a planetary system. The loud humming heard by most sighters of UFOs is, in fact, the purring of several hundred cats.
The one obvious danger is, of course, if the cats manage to eat the bread off their backs they will instantly plummet. Of course the cats will land on their feet, but this usually doesn't do them much good, since right after they make their graceful landing several tons of red-hot starship and irritated aliens crash on top of them.