At NASA's Johnson Space Center (JSC), there is a microgravity research aircraft, a KC-135, nicknamed the "Weightless Wonder." The KC-135 (or "K-bird") is a four-engine turbojet. It is used to fly parabolas to investigate the effects of "zero" gravity. "The Weightless Wonder" has given most of America's astronauts their first taste of weightlessness. The plane's 30-second periods of microgravity are also the final testing phase for experiments and equipment which go on to fly aboard satellites, space stations and the shuttle.