Burping, also known as belching or eructation, is something most of us take for granted here on Earth. We gulp down food and drink, swallow some air in the process, and then release that air from our stomachs through our mouths. This completely normal bodily function allows us to expel excess gas from our digestive system.
However, burping in space is a different story. Astronauts quickly learn that releasing gas onboard spacecraft or space stations is much more difficult than it is on the ground. In the microgravity environment of space, burps just don’t happen in the same way.
What causes burping?
Burping is caused by gas buildup in the esophagus and stomach. When we eat or drink, we inevitably swallow small amounts of air. Most of this air is released through belching. The air we swallow forms gas bubbles which accumulate in the upper portion of the stomach. The ring of muscle between the esophagus and stomach, called the lower esophageal sphincter, allows these bubbles to be pushed back up the esophagus. The opening of this sphincter produces the characteristic burp sound.
Some additional causes of burping include:
- Swallowing air while eating or drinking
- Eating or drinking too fast
- Drinking carbonated beverages
- Chewing gum
- Smoking
- Wearing loose dentures
- Consuming dairy products
- Eating certain high-fiber vegetables like broccoli, onions, turnips
Burping is simply the body’s mechanism for venting excess intestinal gas, usually composed largely of swallowed air or carbon dioxide from beverages.
Why don’t astronauts burp in space?
Belching requires gravity in order to work properly. In the microgravity environment of space, rising gas bubbles don’t separate and collect in the stomach. Instead, they mix freely with stomach acids and digestive juices. Rather than rising to the top to be burped out, gas remains dispersed inside the stomach.
Without gravity’s effects, gas bubbles don’t pool together to be vented out. The esophageal sphincter also loses much of its ability to prevent acid reflux without gravity’s pull. As a result, burping is very challenging for astronauts. The stomach gas and resulting bloating that would normally be belched out on Earth has to go somewhere else in space.
Excess gas is vented through flatulence
Since burping is so difficult in microgravity, astronaut bodies adapt and excess gas gets forced through the other end of the gastrointestinal system instead, leading to increased flatulence. Passing intestinal gas down and out is how astronauts end up venting the buildup of stomach bubbles that can’t be burped out.
Flatulence occurs when gases from the digestion process are passed through the rectum. The absence of burping in space means that this becomes the only remaining avenue for expelling internal gas. Intestinal gases include byproducts of digestion such as methane, hydrogen, and carbon dioxide.
While considered socially unacceptable on Earth, passing gas is viewed as a common and inevitable bodily function in space. Astronauts have reported that it is nearly impossible to hold in flatulence in microgravity. The gases will find a way out eventually, so it’s better not to try.
Space adaptation syndrome
The change in gastrointestinal function caused by weightlessness is actually one of the most common symptoms of space adaptation syndrome. Around 60% of space travelers suffer from this condition, which is somewhat similar to motion sickness on Earth.
Space adaptation syndrome causes nausea, vomiting, headaches, lethargy, and stomach cramps. It occurs as the vestibular system in the inner ear adjusts to weightlessness and no longer provides the brain with accurate information about which way is up and down.
The body interprets these unfamiliar signals from the vestibular system as being poisoned. Difficulty burping and increased flatulence are common components of space adaptation syndrome, as the entire gastrointestinal tract is affected.
Most astronauts find that the syndrome’s symptoms subside after about 3 days as their bodies acclimate to the free-falling microgravity environment. However, around 20% of people in space continue dealing with space sickness throughout their mission.
Other effects of microgravity on digestion
Along with decreased burping, human digestion is altered in several other ways due to zero gravity:
- Reduction in stomach acid production – The lack of gravity means that stomach contents don’t settle, so less acid is needed to break down food.
- Decreased nutrient absorption – Nutrients aren’t pulled down through the intestines as efficiently, resulting in lower nutritional uptake.
- Constipation – Peristalsis, or intestinal muscle contractions, works slower in microgravity. Astronauts often suffer from irregular bowel movements and difficulty fully eliminating waste.
- Deconditioning of the abdominal muscles – Not having to use abdominal muscles to combat gravity leads to atrophy over time.
- Altered kidney function and fluid distribution – The kidneys aren’t as effective at separating liquids and solids to make urine.
The entire gastrointestinal system essentially gets confused by the lack of gravity in space. The body’s normal Earth functions like burping are impaired as a result.
How do astronauts deal with excess gas?
While floating in the spacecraft may look fun, astronauts have to get creative when it comes to passing gas in microgravity. No one wants to be stuck in a sealed metal box with unvented intestinal gases!
Here are some of the ways space organizations and their crews handle the burping problem:
Diet adjustment
Since gas production is directly related to the foods eaten, astronauts are put on restricted diets to minimize gas-causing fare. Items like beans, broccoli, onions, cereals, breads, dried fruit and candy are limited. Carbonated beverages are also a forbidden gas source in space.
Flatulence-inducing foods are minimized, although not eliminated entirely from astronaut diets. Nutritional requirements and caloric intake still have to be maintained for crew health.
Medications
Drugs like Charcoal tablets or Beano are sometimes used as anti-gas remedies. Charcoal absorbs intestinal gases, while Beano contains an enzyme that helps break down hard-to-digest carbohydrates. However, these medications themselves can present side effects like nausea and constipation in the closed space environment.
Filtered airflow
Air filtration systems aboard spacecraft remove smells and gases to keep air quality high. Fans and filters run continuously, scrubbing the atmosphere. Astronauts also individually control the air vents at their workstations for personalized comfort.
Flight suit absorbency
The innermost layer of astronauts’ flight suits are able to absorb some intestinal gas leakage over time. This prevents gases from accumulating directly around the body. However, the flight suits have limited capacity for absorption before needing to be cleaned.
Personal hygiene
Due to the limitations on burping, astronauts have to get used to passing more gas rectally. Passing gas away from other crew members into the ventilation stream is considered good manners in space. Maintaining personal hygiene becomes even more essential in the enclosed environment.
Open communication
Astronauts quickly adjust and develop ways to avoid embarrassment when it comes to passing gas. Odors and noises are simply dealt with cooperatively as a fact of life in weightlessness. Crew members agree to politely ignore minor incidents. Open communication helps prevent tension or discomfort.
Schedule and location
Coordinating schedules and locations can minimize multiple crew members being in a small area when someone passes gas. For example, astronauts may plan workouts at different times. Sleep stations also provide individual privacy for rectal gas release at night.
Gas release valves
Specialized air valves located throughout space stations and spacecraft provide specific releasing points. Astronauts can discretely vent gas into these vacuum lines as needed, separating odors and sounds from the main cabin air. The released gases are then jettisoned into space.
Interesting burping facts in space
While living and working in space presents many challenges, intriguing things have been learned about burping and digestion along the way:
- It’s still possible to burp in space, just very difficult and rare. A sudden closure of the esophageal sphincter can force out a microgravity burp.
- Astronauts have reported being able to voluntarily induce burps by contracting their abdominal muscles or doing certain neck stretches.
- The Apollo astronauts of the 1960s and 70s were provided anti-flatulence pants to help vent stray gases.
- The space shuttle toilet even had a special air flow system to pull any expelled intestinal gases away from the crew member’s body.
- Astronauts have described experiencing a wet burp or “wetuction” after drinking carbonated beverages. The bubbles pool in their stomach before being forced upward.
- Solid foods like nuts lead to more swallowed air and gas issues than pureed foods.
- Women astronauts have reported fewer issues with gas and flatulence than their male counterparts.
- Burping is very difficult on parabolic zero-gravity airplane flights used for astronaut training. Motion sickness medications taken before the flights aggravate the problem.
- NASA and other space agencies have funded research on how to treat gastrointestinal issues during space missions to improve crew health and comfort.
The future of burping in space
As space missions become longer with travel to the Moon and Mars, the gastrointestinal effects of microgravity remain an obstacle. However, space programs are committed to reducing the issues through a combination of diet, medication, technique training, and technology improvements.
Possible future burping innovations include:
- New pharmaceuticals tailored to space travel
- Artificial gravity modules to provide intermittent gravity
- Improved ventilation systems
- Gastrotrointestinal monitoring devices
- Personalized nutrition programs
- Advanced skin absorption technology for venting gases
- Gastrointestinal microbiome studies
With extensive focus and research, space travelers can hopefully belch like they do on Earth again someday! For now, increased flatulence prevails in the pursuit of the cosmos. Our bodies continue adapting to the unique conditions of life in zero gravity.
Conclusion
Burping requires gravity to work properly. In the microgravity environment of space, excess gas and air swallowed while eating and drinking doesn’t separate in the stomach to be belched out. Instead, the gas mixes freely and has to be eliminated by passing rectally instead.
This causes issues like space adaptation syndrome, abdominal discomfort, and increased flatulence for astronauts. Spaceflight changes many aspects of digestion without the effects of gravity. Besides diet adjustments and medications, astronauts employ methods like air filtration, gas release valves, and open communication to deal with the gas.
While living in space comes with many physiological challenges, space programs continue working to minimize the gastrointestinal effects that impair burping. As space travel endures longer and farther than ever before, solutions to allow normal belching on spacecraft will hopefully be developed to aid crew health and comfort. The future promises innovative approaches to rectify the curious lack of burping in space.