All the regional winners from the YouTube Space Lab competition. Courtesy of YouTube. (Bryan Rapoza/BRYAN RAPOZA WWW.AVENFOTO.COM)

As the plane takes off for the zero gravity flight, even the most seasoned air travelers are fidgeting. Part of it could be nerves, but most of that excess energy comes from the excitement. Soon, the passengers think, we’ll be floating around this plane.

For Emerald Bresnahan, the anticipation is extra sweet. Not only is she a regional finalist in YouTube’s Space Lab competition and taking this unusual trip on her 18th birthday, it’s also the first flight of her life.

She is one of nine finalists on the plane, joined in flight Wednesday by representatives from YouTube and Lenovo, and some press folks — including yours truly. Ahead of the flight, she’s all smiles and jokes, telling me that she’s already planned out the flips she’ll be doing as we float. On the plane, I’m fiddling with my flight suit. But Bresnahan is calm, far calmer than what you’d expect of anyone on their first flight, especially one that includes 15 parabolic maneuvers that result in about eight minutes of total weightlessness.

Terese Brewster, the president and chief operating officer of the Arlington, Va.- based Zero Gravity Corporation, said that passengers’ inability to describe the feeling is one of her biggest marketing challenges.

“We can tell you what it’s not like,” she tells me ahead of the flight. “It’s hard to say what it is like.” Still, the appeal of the flights allow the company to book them, at around $5,000 a pop, for weddings and even family vacations.

For Emerald Bresnahan, center, this weightless trip was the first flight of her life. All the regional winners from the YouTube Space Lab competition. Courtesy of YouTube.

As we get to altitude, I’m acutely aware of every rise and fall, a small preview of what’s to come. Soon, the coaches tell us to take our places lying on the floor, with our feet towards the cockpit to avoid motion sickness. (For a handful of participants on our flight, this tactic doesn’t work as well.)

We start slowly, with the pilots pulling off a first maneuver meant to simulate the way gravity feels on Mars. As the plane climbs, we feel the pressure of 1.8 times the force of gravity, and lifting my leg feels like an arduous task. Then, suddenly, the weight drains away and we start to lift. People around me are giggling as they do one-handed pushups. Next we do two lunar parabolas, which take us to about 1/6 of our body weight. Now the push-ups are done on one fingertip. I shoot a thumbs-up at Emerald, nearly upside-down with her ponytail flying, which she returns with a grin.

Finally, the pilots take us into the weightless dives. We get twelve of these in all, each lasting a little over 30 seconds. Again, the feeling is gradual, as if the weight of your body is simply draining away. And then we’re floating off the floor, headed toward the mercifully padded ceiling. I scramble for the guide ropes to keep from colliding with another passenger.

Being weightless is simultaneously the most chaotic and most calming experience I’ve ever had. My body is completely at ease while my mind races to find the proper orientation. Floating is, of course, the coolest part, but so is the absence of any pressure on your joints. In fact, one woman on the flight mentions that pain from a pinched nerve that’s been bothering her completely disappears while we’re in the air.

By the time we’ve done a few of the dives, the finalists — including the winners announced Thursday, Dorothy Chen, Sara Ma and Amr Mohamed — are all laughing, spinning and flipping through the air. They get playful, trying to drink water out of the air or play catch. Meanwhile, I ambitiously try a flip only to find I haven’t given myself enough momentum and get stuck upside-down. I decide to stick to spinning and floating.

As Brewster says, it’s much easier to say what the experience isn’t like than what it is. It’s not like the moment at the top of a roller coaster. It’s like being underwater, except it’s not at all like it, since there’s no feeling of buoyancy. And it’s not like swimming. In fact, the coaches tell us ahead of time: don’t try to swim. You’ll just end up kicking someone in the face, they say — as I am sad to admit I did once while trying to regain my sense of up and down.

After we touchdown, I run up to ask Bresnahan about her reactions to the flight. To my surprise, Emerald — whose experiment looked into the connection between the way snowflakes and galaxies form — says that she loved being able to see clouds from the top.

“It was so cool to see them from that angle,” she replies. “They were like mountains.”

And the zero gravity?

“Oh yeah,” she says, with laughter in her voice. “That was cool, too.”

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