text: if a astronaut farts in zero g do they fly accost the room?   no they don't.  in actual fact, the abnormalities of flight do involve  quite a number of changes in air pressure as you climb above the surface of the earth and fly through various manuvers which exert "g" forces on your  body.  the human body has two ports for equalization of  internal pressures: the throat and the rear end. so while this might sound a bit humorous, there is a  lot of burping and pharting involved in flight.  since the internal atmospheric pressure within most space ships and stations is just slightly  more than 1 atmosphere, the gas velocity exiting the rear end during a space phart would be no faster than that of a phart here on earth. other  than a slight lift to release the gas, no actual motion would be detected by an observer during the phart.  other astronauts in the general vicinity would, however, move away from the immediate area unless restrained by the elaborate seat belt arrangements during docking or manuvers.  the real problem which you failed to ask about is the  internal climate within a space suit. what happens  inside there during pharting? well, i must admit that in a confined space there is nothing so disturbing as a string of continual pharts. your helmet visor becomes  clouded and cleared again by the suit conditioning  system, or external support system equipment. luckily the pressurized suit support systems are designed to handle these occasional bursts of methane gas.