Experiencing Weightlessness

The Zero G Experience!

“As the Stomach Turns” on the KC-135

Astronauts in zero gravity training onboard the KC-135, affectionately known as the "Vomit Comet", get a unique perspective of their environment during a zero gravity flight. Medical studies and motion sickness experiments are also researched on these flights. The NASA Reduced Gravity Program began in 1959 and the KC-135 was the perfect aircraft. The Boeing four- engine turbojet Stratotanker was originally designed for in-flight aircraft refueling and later as a 707 for commercial flights.

The diagram above shows a flight plan for the KC-135 during typical zero-g maneuvers. During a typical mission of 2 to 3 hours, the aircraft will fly 30 to 40 parabolic arcs. During each parabolic arc there are 20 to 25 seconds of "g" gravity when the astronauts will experience how it feels to be in outer space.

How did they film the “zero gravity” scenes in the movie Apollo 13? Creating weightless scenes for the movie would have been no problem if the crew could have filmed in space. But that would have sent the movie's budget to the Moon! So instead, the actors did what real astronauts in training do: they flew in NASA's "zero-gravity" plane, nicknamed the Vomit Comet. The cast and crew flew between 500 and 600 parabolic arcs in NASA's KC- 135 airplane (nicknamed the "Vomit Comet") to achieve real weightlessness. Each of the arcs got them 23 seconds of zero-gra vity. All of these flights were completed in just 13 days. The plane climbs and dives, coasting over the top of an invisible parabolic arc. When the Vomit Comet reaches the bottom of its roller-coaster-like dive, the plane slowly pulls out of its parabolic dive and the zero-gravity environment disappears. As the plane climbs again, the cast and crew hit the deck. When gravity took hold of the Apollo 13 cast, says Hanks, the well-trained NASA crew would hold on to the actors so they wouldn't crash on top of the cameras or each other.

Note: Assuming that the plane’s altitude was decreasing for half of the 23 second zero-gravity experience, the plane and crew are free-falling at around 250 miles per hour! Before climbing on board the Vomit Comet, the cast and crew swallowed a potent medication that astronauts take to keep them from losing their lunch. Then, the film crew loaded mock-ups of the spacecraft, lights, cameras, and other equipment needed to film the movie. Each Vomit Comet zero-gravity arc lasts only 23 seconds, so the cast and crew had to work fast. These are the scenes where actor Bill Paxton, as astronaut Fred Haise, spins his sunglasses toward the camera, and actor Kevin Bacon, as astronaut John Swigert, squirts orange juice into the air.