Astronauts that go into space have to be prepared to handle weightlessness. It's a totally different feeling from being on Earth where you're constantly pulled towards the ground, and in many cases, it can be nauseating without the proper training because not only are our bodies not used to it, but they weren't really made for it either.
One of the various ways that astronauts will be subjected to weightlessness before going into space is with a special plane ride commonly referred to as the ‘vomit comet' because of its tendency to make people vomit.
The plane follows a very special parabolic flight pattern that can easily simulate the illusion of weightlessness. It does this by taking nose dives that essentially fall faster than the speed of gravity, which gives anyone on board the feeling of floating for steady 20-second bursts.