Training to become an astronaut requires an applicant to endure physically demanding and stressful tests -- various machines and simulators measure each trainee's response to the rigors of space travel. Today, an entirely unrelated industry uses many of these simulators and other devices for a different purpose -- entertainment.

A low-gravity game of catch
Photo courtesy of Zero Gravity Corporation
Playing catch with a fellow passenger in a low-gravity environment

Few of these simulators appeal to the general public more than the zero-gravity flight. Almost everyone dreams of floating effortlessly like astronauts in space. Currently, NASA uses a modified C-9 plane to create simulations of a weightless environment, both for training purposes and to conduct weightlessness experiments (without the enormous costs of space travel). Until recently, only a select few had the privilege of experiencing these flights. Today, a company called Zero Gravity Corporation (ZERO-G) offers this experience to the general public.

In this article, we'll learn about gravity, free-falling and what it's like to board the so-called "vomit comet." We'll start with what it's like to experience weightlessness.