It is impossible to burp in space, because in microgravity the human stomach cannot separate gas from the liquid and partially digested food it sits inside, and any attempt to burp expels a mixture of all three directly into the astronaut's mouth.

It is impossible to burp in space, because in microgravity the human stomach cannot separate gas from the liquid and partially digested food it sits inside, and any attempt to burp expels a mixture of all three directly into the astronaut's mouth.

The mechanism behind a burp on Earth is something most humans do not stop to think about. Food and drink enter the stomach. The act of swallowing brings air down with them. The acids and enzymes in the stomach break down the food and produce additional gas as a byproduct of digestion. The gas accumulates. It needs to come back out, because if it does not, the stomach distends and the pressure becomes uncomfortable. Most people release this gas d…