What it was like to feel simulated lunar gravity on a stomach

Jan 08, 2024

There is only one way to experience lunar gravity while still on Earth: a parabolic airplane flight.

Join our Q&A with ESA parabolic flight coordinator Neil Melville and Space.com senior writer Tereza Pultarova at 12:00 p.m. EDT (1700 GMT) on Wednesday, June 7.

In lunar gravity, your body is so light you feel like a superhero, suddenly capable of the most advanced calisthenics skills: One arm pull-ups? The challenging L-sit position when your entire body weight rests on your hands? On the moon, no problem! But experiencing lunar gravity while still on Earth has its challenges.

Like many of the best opportunities in life, my "ticket" for a parabolic flight simulating lunar gravity arrived by serendipity. In February this year, I interviewed anesthesiology professor Alexander Chouker from Munich University in Germany about European research into hibernation for long-duration spaceflight. The story turned out to be my best-read article of that month, which by itself brought me a lot of satisfaction.

Shortly after the story was published, I received an email from Chouker. The subject line alone made my heart beat faster. "Parabolic flight?" it read.

A prominent expert in space physiology and the effects of space on the human body, Chouker was to fly a cell experiment on a parabolic flight simulating lunar and Martian gravity. The flight was to take place in late April and there was a seat available for a journalist. Would I be interested in being put forward as a possible candidate?

It was one of those emails you answer without even engaging your brain.

"Absolutely! What a wonderful opportunity! Thank you for thinking of me!" I hit "send."

Related: How do you create lunar gravity in a plane? A veteran zero-G pilot explains

A fraction of a second later, a wave of panic washed over me. How on Earth am I going to handle this? Throughout my childhood, every school trip was a nightmare. I was that notorious kid with the sick bag — the one who had to sit at the very front of the bus with the teachers while the cool kids were having fun at the back. I remember being fed anti-motion sickness pills that were so bitter that their taste on my tongue was enough to make me even more nauseated. Every family car trip required stocking up on bags and chewing gum. Even in my adulthood, a few whale-watching trips in the Canary Islands turned into ordeals.

I hadn't been on a parabolic flight before, but I knew the nickname for these flights: The vomit comet.

Parabolic flights create weightlessness or reduced gravity conditions by following an up-and-down trajectory of steep climbs and nerve-racking dives. During these aerial roller coasters, passengers onboard experience brief spells of nearly double the force of Earth's gravity both when the plane accelerates and pulls up and when it descends. At the peak of each parabola, there is a short less-than-30-second period of zero or reduced gravity. During a scientific flight, such as the one that was offered to me, pilots perform 30 such maneuvers in quick succession with only short breaks in between. That's enough to make even the cool kids from the back of the bus sick!

But it was simply one of those opportunities that you can only accept with gratitude and pray for the best. When it transpired that the flight would take place on my 40th birthday, it felt almost like a challenge from the universe.

I shared my concerns about getting sick with Chouker and later with the flight organizers, representatives of the European Space Agency (ESA) and the French company Novespace, Europe's only provider of parabolic flights. I also talked about my concerns on social media. Everybody I knew who'd been on one (or many) such flights was reassuring me: I would receive an injection of a strong medicine, much stronger than the regular motion sickness pills available over the counter or that bitter stuff of my childhood. It works wonders. "You will be absolutely fine," some of them predicted.

I passed my medical examination (a history of childhood motion sickness fortunately doesn't exclude you from taking part in parabolic flights) and continued looking forward to the big day with a mix of excitement and dread.

The flight was to take place from Bordeaux, a city in the south of France most famous for its production of wine. During an online preparation meeting, it was made clear to me that this wouldn't be one of those free-flying experiences that rich tourists can buy. There will be no weightlessness, only lunar and Martian gravity, and the flight will be packed with scientific experiments, which meant that I wouldn't be allowed to jump around like a kid in a bouncy castle (that was a little disappointing; I may be the notorious kid with a sick bag, but I am also a keen gymnast). But they would find a way for me to experience and demonstrate what it feels like to be on the moon. There would be a cameraman on board, an experienced flier, who would help me relay the experience to my readers.

I arrived in Bordeaux two days early. Despite it being nearly the end of April, the weather wasn't great, but decent enough for me to spend a relaxed Sunday afternoon exploring the old town. (Bordeaux has a magnificent gothic cathedral with the most breathtaking stained glass windows and one of the largest organs in the world.)

On Monday morning, the day before the flight, I was to report to Novespace premises to film interviews and tour the aircraft. The building, tucked away on the other side of the Bordeaux airport from the terminal, is essentially a large workshop with offices scattered around. When I arrived, preparations for the flight, which was to be the first in a three-flight campaign conducted that week, were in full swing.

Here I met Neil Melville, ESA's parabolic flight campaign coordinator, and Sébastien Turay, ESA's go-to parabolic flight cameraman. Both of these men had flown dozens of times, or, as the parabolic flight folks like to say, had hundreds of parabolas under their belts. They were to serve as my minders, making sure that my presence on the flight wouldn't cause too much disruption.

I received my badge and an ESA flight suit (a bright blue one just like those that astronauts wear) and was escorted to the aircraft. Novespace flies an Airbus 310 that in its previous incarnation served the former German chancellor Angela Merkel. In 2014, when the company bought the plane from the German government, it stripped off all the fancy furnishings of the Merkel era and created a large empty space with soft railings to help people stay in place and lots of berths for science experiments. I learned that even toilets had been removed, which made me a little anxious as our flight was to last nearly three hours. But as it transpired, I would be occupied with a different type of bodily fluid during the flight.

Inside the white, padded cabin, a team of ESA researchers led by Europe's chief astronaut trainer Hervé Stevenin was sorting out a batch of experiments, including a device, a type of wheelbarrow, that could in the future help astronauts transport equipment on the moon. Another team was readying a 3D printer that manufactured simple tools from a mixture of plastic and lunar dust. Both of these devices were to be operated in lunar gravity for the first time.

In the cockpit, I met Eric Delesalle, Novespace chief pilot and captain of my flight. The aircraft's "control room" looked rather normal to my layperson's eyes: cramped and tiny. I hit my head on the low, instrument-covered ceiling as I was squeezing myself into the co-pilot's seat to interview the veteran aviator.

As I was to learn, nothing would be "normal" during the flight. For starters, unlike on the EasyJet flight that I had arrived on from London, there would be four pilots on board, three of them actively controlling the aircraft at the same time.

Novespace claims to be the only operator in the world capable of generating reduced gravity conditions with scientific precision. When they say they fly you "to the moon," you will feel exactly like you would on the moon, not "just about." To do that, the pilots need to follow the up and down trajectory with surgical precision. During the flight, three pilots are actively controlling the aircraft at the same time: one executing the pitch (the up and down motion of the aircraft); another in charge of the plane's roll (its tilt to each side); and the third acting on the throttle to control the plane's speed. After each set of parabolas, one pilot takes a break and the fourth crewmember steps in.

Before heading to the hotel that evening, I managed to catch up with the flight surgeon. He reassured me that the anti-vomiting drug that I was to receive cuts the probability of nausea to one in 10. During the hypergravity phases when the aircraft steeply rises and descends, I was to keep my head steady. He recommended I get a good night's sleep and eat a normal breakfast no later than two hours before the flight, and I should be fine.

I still wasn't convinced. I did the math. One in 10 didn't sound reassuring enough. But I was determined to follow the instructions and make the best of the experience no matter what. However, my over-excited nervous system had a different idea, and my night didn't turn out particularly restful. I still managed to drag myself out of bed in time in the morning to have an early enough breakfast. I particularly enjoyed the freshly made orange juice.

When I arrived back at Novespace, everyone was in their flight suits. I was ushered to the front of the queue for the anti-vomit shot.

"You might feel a little drowsy," the doctor said.

And then I headed to interview Jean Francois Clervoy, Novespace founder and a retired French astronaut who flew on one of the Hubble Space Telescope servicing missions. I was star-struck and wanted to do a good job. But halfway through the interview, something happened in my head. I began to feel funny, sort of detached from myself and everything around me. Like on …. drugs, I thought (although I don't have much experience in that department). I finished the interview thinking everybody could see that I was a bit high. I shared what was happening to me. Clervoy laughed: "Just have a cup of coffee — you'll be fine."

It was time to get on board. I decided to give in to the experience, drugs and all.

We were to fly west of Bordeaux, above the Atlantic Ocean. There were forty of us at the back of the plane, seated behind a soft mesh partition separating the padded space. The plane took off. Melville encouraged me to look out of the window to notice the aircraft was climbing at a much steeper angle than commercial airliners.

We flew for maybe 15 minutes. Then a voice from loudspeakers instructed us to assume our positions in the experimental area. The scientists headed to their devices. I was shown to my spot on the floor between the lunar wheelbarrow, a virtual reality experiment and an experiment using ultrasound to study how the position of human organs shifts in reduced gravity.

It was happening too fast for me to get anxious. The voice from the loudspeakers began the countdown for the first parabola: "One minute … 30 seconds, 20… 10."

Melville instructed me to lie on the floor, the most comfortable way to experience hypergravity for the first time. The crew and experienced fliers remained standing.

"Pull up," a voice then said over the loudspeaker. The engines roared. I felt the organs in my body pressing me to the ground. Something was tugging on my skin. It felt as if I were melting into the floor. This was gravity pressing me down with 1.8 times the force of what we live with on our planet. I didn't like the feeling one bit.

But then, "injection." In a split second, the heaviness was over. Melville encouraged me to sit up. I had brought with me a lunar gravity indicator, a soft toy moon handmade specifically for this occasion by Space.com reference writer Daisy Dobrijevic. I tossed it in the air and it flew up in slow motion, much higher than I had expected. Melville caught it, visibly concerned that my lunar gravity antics may disrupt the experiments on board. Stevenin in front of me was confidently hopping in slow motion along a test track like a seasoned moon explorer, his movements recorded by motion capture cameras. I threw my moon in the air some more and couldn't control the yelps of excitement escaping from my mouth. I wasn't alone. Lunar gravity felt magical.

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After less than 30 seconds, the voice from the loudspeakers began the countdown again and the plane had swung over the crest of the parabola. We would soon begin our powered descent. I rushed to assume my position on the floor.

"Pull-out."

I felt the weight of my internal organs again. Then, about 20 seconds later, we resumed steady flight. A minute and a half of normal gravity. And then it started again.

Gradually, I was gaining more confidence. I even allowed myself to sit through one of the hypergravity phases, but I didn't like the feeling in my head when 1.8 G changed to lunar G, so I decided to play it safe. I played with the ball some more, impressed with my ability to control it in slow motion like a rhythmic gymnast or a footballer, and then attempted some lunar calisthenics. Being in lunar gravity is like a combination of being on a trampoline and in a swimming pool, with the added quality of slow motion. I felt I was getting the knack of it, but Melville was apparently growing concerned as I was obviously forgetting to pay attention to those around me.

As much as I enjoyed lunar gravity, the hypergravity phases remained unpleasant for me. By the end of our first set of lunar parabolas, nausea crept in. I left the experimental area and tried to get some relief in my seat. We had about five minutes of steady flight without the constant gravity changes. But Melville didn't let me rest long. One of our pilots had a break and came to see the experiments. He was none other than France's celebrity spaceman Thomas Pesquet, and he agreed to talk to me.

I had already managed to interview one astronaut while feeling out of my head, and now I was at risk of throwing up on the flight suit of another. This certainly was a 40th birthday celebration I couldn't have dreamt up.

I was able to ask two questions before the loudspeaker announced we were about to start the pull-up again. Pesquet reassured me I was doing all right, but I cut the interview short to seek a safe position on the floor. He walked off to assist Stevenin with the wheelbarrow experiments.

Our next set of parabolas created the gravity of Mars. Roughly 40% that of Earth, Martian gravity felt a little less exciting than that of the moon, which is about one sixth that of our planet. I was also getting tired. The rush of dopamine and god-knows-what I had experienced during the first lunar phase was wearing off. The hypergravity phases began to drain me more, and I was enjoying the reduced gravity a little less. I also started to be more aware of the science experiments around me and no longer wanted to act like a kindergarten kid while everyone else was seriously at work. Melville seemed relieved.

In hindsight, I wish I had been more confident during the hypergravity phases. Later that day, Stevenin told me that the best way to handle hypergravity is to keep your stomach muscles in and breathe shallow and fast. Oh well. I was doing it all wrong, trying to manage my discomfort with some deep, slow yoga breathing. But never mind.

After seven Martian parabolas, we had another break, then one more lunar and one more Martian set to go. I concluded that I felt the most comfortable dealing with the hypergravity on the floor than in the seat, but things were getting increasingly difficult. I made it through the second lunar set, but when I wanted to record a short sequence during the next break, I could tell from Melville's and Turay's expressions that I didn't look particularly well.

Soon, the nausea set in again, and this time it was there to stay. I spent the final set of Martian parabolas in my seat, living up to my childhood reputation of the sickest kid on the trip. I would never have guessed how long orange juice stays in your stomach.

When the final parabola arrived, I felt relief. The flight was certainly the most intense thing I had done in my whole life. For the rest of the day, apart from still feeling quite funny in my head, I would be experiencing physical sensations as if something was squeezing my body, tugging at my skin and pressing at my internal organs.

Would I do it again? You bet! But next time with weightlessness.

Follow Tereza Pultarova on Twitter @TerezaPultarova. Follow us on Twitter @Spacedotcom and on Facebook.

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Tereza is a London-based science and technology journalist, aspiring fiction writer and amateur gymnast. Originally from Prague, the Czech Republic, she spent the first seven years of her career working as a reporter, script-writer and presenter for various TV programmes of the Czech Public Service Television. She later took a career break to pursue further education and added a Master's in Science from the International Space University, France, to her Bachelor's in Journalism and Master's in Cultural Anthropology from Prague's Charles University. She worked as a reporter at the Engineering and Technology magazine, freelanced for a range of publications including Live Science, Space.com, Professional Engineering, Via Satellite and Space News and served as a maternity cover science editor at the European Space Agency.

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