As a child of the Space Age, born in the same year as Gagarin and Shepard’s historic flights, I have always fantasized about floating in zero gravity. In college, I studied orbital mechanics and rolled my eyes at stories and films that got zero-g wrong. And as a science fiction writer, I have often used zero gravity settings (notably in my debut novel Arabella of Mars) and took pride in getting the physics right. So when I got the opportunity to experience zero gravity myself, thanks to a very generous birthday gift from my father, I was thrilled, and also confident that I would know how to conduct myself in free fall.
Let me tell you this: the thrill was real, but the confidence… well, maneuvering in zero gravity is a lot harder than it looks.
The Zero-G Experience offered by the Zero Gravity Corporation (gozerog.com) consists of about fifteen parabolas in a modified Boeing 727. At the top of each zero-g parabola, the pilots direct the plane through the same path it would travel if it were not under thrust, which means that the plane and everything inside it experiences free fall. This is exactly the same phenomenon as the microgravity experienced by astronauts in orbit, but without leaving the atmosphere. On each iteration you get about 30 seconds of zero gravity, for which you pay with a few minutes of nearly two gravities at the bottom of the parabola. (Two gravities isn’t that bad; it’s like the heaviness you feel when you first get out of a swimming pool. But you really want to be close to the floor when it hits.)
This technique of flying parabolas was first used for astronaut training in the 60s, on an aircraft nicknamed the “Vomit Comet,” and the first question nearly everyone asks is whether I got sick. But the astronauts did 30-50 parabolas on each flight; the people who run these tourist flights have determined that 15 parabolas is enough to have some serious fun but not enough to make most people airsick. And, indeed, at the end of my flight I felt okay, but like I’d ridden the Tilt-A-Whirl several times and one more ride might be too much.
The experience of zero gravity is notoriously difficult to describe. It isn’t like floating in the water, it isn’t like jumping on a trampoline, and it isn’t like hanging upside down. It’s like sex – wonderful, difficult to put into words, and you want to do it again. Soon. A lot. One thing I can say is that it is such an unusual physical sensation that you focus on your own personal experience, which means that you don’t tend to notice what other people around you are doing (unless you happen to carom off of them, which is common). I saw things in the post-flight videos that had been happening right in front of me and I had not noticed at all. Another thing about zero gravity is that it is not the same as moving in slow motion – it is real life and moves at full speed. “You think it’s going to be The Blue Danube,” said our in-flight photographer, “but it’s really more like Yakety Sax.” The reason astronauts move slowly is that they’ve learned that if they don’t they bang their heads on things.
I understood how to move in zero g – in theory. But the difference between theory and practice is always smaller in theory than it is in practice. It turns out that just knowing that you are going to keep whatever velocity and spin you have when you depart a surface, until you meet up with something else, is not the same as being able to do anything about it. And so I spent a lot of time flailing my feet in midair, which doesn’t help at all. It was still a heck of a lot of fun, and I imagine that if I had more than thirty seconds at a time to learn, and were provided with an environment that wasn’t simply a large, empty, padded cylinder, I would probably pick up the trick fairly quickly.
Another big surprise was the experience of Mars gravity. The flight starts off with one parabola at Mars gravity (one-third of Earth’s) and two at Moon gravity (one-sixth) to help you acclimate. These three parabolas were a lot of fun, and easier to move around in than free fall, but I was astonished how light I was on Mars — I could easily push off the floor with one hand and hit the ceiling. This is something that’s almost never portrayed in movies and TV set on Mars (for obvious reasons) but it is, after all, closer to Moon than Earth gravity. This would be a very good thing for astronauts who arrive on Mars with weakened muscles after months in free fall, and I’ll try to keep it in mind the next time I write something set on Mars.
The Zero Gravity Corporation is a very strange airline. They have one aircraft, every one of their flights begins and ends at the same airport, and one flight makes you a frequent flyer. But they can take you to a destination no other commercial airline can match, and if you can spare the money for a flight I would definitely recommend it.