By Jonny Lupsha, Wondrium Staff Writer
Amazon founder Jeff Bezos has landed back on Earth after experiencing weightlessness during space flight. He used part of his fortune from the online shopping company to pay for his recent trip to the edge of space. But is “weightlessness” real?
The world’s richest are paying to experience the weightlessness of outer space, known as zero gravity. Amazon founder and ex-CEO Jeff Bezos recently spent 11 minutes high enough in the atmosphere to feel the sensation. Upon his return to being on Earth, he gave away $200 million to charities and nonprofit organizations. However, both the terms “weightlessness” and “zero gravity” are at least a bit misleading.
In his video series Physics in Your Life, Dr. Richard Wolfson, Benjamin F. Wissler Professor of Physics at Middlebury College, did some myth-busting and burst the bubble on both verbiages through the lens of physics.
Gravity: Always Letting Us Down
Most of us have seen video footage of astronauts in space, floating around in spaceships, the International Space Station, or even outside on spacewalks. They seem to be truly weightless and free from the gravity we experience every day on Earth. Are they?
Yes and no.
“Weight is a force that gravity exerts on you,” Dr. Wolfson said. “Frankly, people say, ‘Well, there’s no gravity in space; that’s why astronauts are weightless.’ That’s absolutely nonsense. If there were no gravity in space, there would be no force acting on the spacecraft, or the astronauts, and they would happily move in a straight line at constant speed forever.
“We would never see them.”
On the contrary, all objects fall with the same acceleration. So when you’re in a situation in which you’re falling, like a spacecraft, everything around you undergoes the same acceleration as you and other objects.
For example, if someone holds an apple while they stand on a high diving board at a public swimming pool, and they jump feet first from the board and let go of the apple, they may see the apple “floating” in front of them and they themselves may feel weightless. However, they are accelerating rapidly towards the surface of the Earth—and hopefully not in a belly flop.
This is the same as what happens in outer space, with objects like space shuttles and astronauts always falling toward Earth but always missing due to the arc of flight. They’re only under the influence of gravity, without the forces of Earth’s surface, or a swimming pool, pushing up against their feet.
Does It Have Those Little Sickness Bags?
“NASA has also developed an aircraft; it’s called a ‘vomit comet’ because of what happens to people in it,” Dr. Wolfson said. “It flies in arcing parabolic trajectories that, near their peaks, simulate the motion of an object falling under the influence of gravity alone, moving under the influence of gravity alone in a parabolic arc.
“Because an aircraft is subject to aerodynamic forces, that trajectory has to be carefully engineered so that the aerodynamic forces basically cancel out in a way that makes the trajectory be exactly what would happen under the influence of gravity alone.”
The popular film Apollo 13 starring Tom Hanks was partially filmed in the vomit comet. This was done in order to simulate the feel of space flight. However, Dr. Wolfson took issue with the word “simulate” in this example.
“The weightlessness associated with free fall, whether it’s happening right here at the surface of the Earth, or in that vomit comet aircraft, or in a spacecraft in orbit around the Earth, in orbit around the Sun, on the way to Jupiter, or wherever—so long as its rockets aren’t firing, and so long as no non-gravitational forces are acting, that state […] is as truly a ‘weightless’ state as anything any astronaut feels,” he said.
Not all of us need to fly to the edge of space to experience it.