04. At what altitude will we reach zero-gravity? What does one feel like when suddenly leaving the Earth's gravitational force? Do you feel like you want to grab onto something? (A K2S Question)

From The Space Library

There is no set altitude. Achieving the feeling of weightless can be accomplished through a variety of methods at various altitudes. When you first realize that you've left gravity's grip, it feels weird—like someone or something released you to float around. Most people try to swim their first time in zero-gravity, because swimming is the only thing they've ever experienced that is even a little bit similar. It is difficult to understand that there is no altitude where zero-gravity is reached. Regardless of how far you travel from the Earth there will always exist a slight gravitational pull towards it. Let's think about this. Imagine that you are riding a roller coaster over the crest of a hill shaped like a parabola. Now, at the proper speed, the seat will move through the path that your body would naturally want to move. This would cause the seat to stop pushing on your body, which would make it feel like there was no gravity (even though gravity is present and in fact controlling your path). The same theory applies to zero-gravity airplane flights, like the ones NASA uses to train the astronauts. Here's what happens: the airplane essentially throws you through a certain curve and then follows that path. Since this is the path that your body would naturally follow, you feel weightless because the airplane is traveling with you, but is not touching or pushing on you, as is the case in normal gravity conditions. This is the same reason that Mike Melvill was able to have M&Ms float around the cockpit of SpaceShipOne.

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Answer provided by Dana S. Klein & D. Brooke Owens

Question and Answer extracted from the book Kids to Space - by Lonnie Schorer

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