Can Astronauts Burp in Space? (Image courtesy of NASA)
Digestive gases get the better of everyone at one time or another, often in the form of burping. Burping is the body's method of releasing excess gas in the upper digestive tract, which would otherwise lead to extremely uncomfortable pressure in the stomach and esophagus.
Or at least that's how it works on Earth. In space, things are a little different, since there's no gravity. So is it really impossible to burp in space? The answer isn't as simple as you might expect.
Experts explained to Live Science that in microgravity, burping is impossible the way it is on Earth. That’s because, unlike vomiting, which uses the muscles of the digestive tract to push food back up, the mechanics of burping are entirely dependent on gravity. First, gravity helps separate the gaseous components of burp from the liquid and solid remains of food in the stomach; gas is lighter and therefore rises. So before burping occurs, a layer of hot, sometimes foul-smelling gas forms in the stomach, hovering above the thick mixture of partially digested food.
When there is enough gas, it puts pressure on the sphincter (a muscular ring that acts as a barrier between parts of the digestive system) between the esophagus and the stomach; the sphincter opens, allowing the gas to rise into the lower part of the esophagus. A second sphincter, located higher up, allows the rising gas to enter the upper part of the esophagus, where it can be expelled as a burp.
“In space, the air and fluids in your stomach can’t separate like they do on Earth,” Raffi Kouyoumdjian, chief medical officer for operational space medicine at the Canadian Space Agency (CSA), told Live Science. Without gravity to sort your stomach’s contents, it’s just one big, lumpy, gassy mess. In space, as on Earth, you can try to burp by drinking a carbonated drink, gulping air and holding it in, and then tensing your stomach muscles — but if you do that in microgravity, it will result in, as astronaut Chris Hadfield described it in a 2018 post on Twitter (now X), “lumpy bubbles.”
Gravity also helps you burp, through a process known as convection. When a gas or liquid is heated, its molecules spread out, making it less dense (and therefore lighter) than the surrounding gas or liquid. This is why you see columns of bubbles rising in a pot of boiling water, why the surface of the sun is covered in convection cells, and why the hot gas from a burp inevitably rises from your stomach, backs up your esophagus, and exits through your (hopefully politely covered) mouth.
However, without gravity, convection does not function. Without gravity to pull the contents of your stomach, it does not matter whether some items in an astronaut's diet are heavier or lighter than others.
“In zero gravity, there is no up and down, so gas cannot ‘rise’ from the stomach to be burped,” Kuyumdzhyan noted.
The good news is that astronauts don’t have to worry about a badly timed burp in the middle of their workday. When asked about the physiology of burping in space, Adrianos Golemis, a surgeon in charge of human spaceflight at the European Space Agency and the French space agency CNES, noted that “it’s never been mentioned in the post-flight reports.” (The pun may or may not have been intended.)
However, some may face another potential problem: “Instead of burping, astronauts may experience reflux of stomach fluid and gas,” Kouyoumdjian said. Reflux occurs when the sphincter between the stomach and esophagus relaxes, allowing stomach
Sourse: www.livescience.com
