Human spaceflight rests on the shoulders of kitties. Before shooting humans into space, NASA and the U.S. Air Force tested the low-gravity waters with smaller mammals, birds and insects. The propaganda videos of the time claimed the animal astronauts were ushering in "a new era -- not a Buck Rogers era in a science fiction world, but an age having its foundations in research." That may be true. But the resulting videos of these hapless creatures, which range from hilarious to disturbing, seem to best answer the question, "How does a creature that doesn't understand gravity respond to its absence?"

Cats only land on their feet when they know which way is down. Researchers at the Air Force Aerospace Medical Research Laboratories in Dayton, Ohio sent cats flying in a C-131 jet on a trajectory that gave them 15 seconds of weightlessness. This footage is from an Air Force film called Bioastronautics Research.

Video: U.S. Air Force Aerospace Medical Research Laboratories