Can a fire start in space?
In space, where there is no atmosphere and oxygen, as in terrestrial conditions, fires cannot occur. A fire requires oxygen to burn, as well as fuel and the right temperature.
However, in space stations or spacecraft, there is a potential fire hazard due to equipment, chemicals, or other materials that can support combustion.
Fires happened at the Mir station in 1994 and 1997. In the first case, the fire was extinguished with a spare working suit, in the second case, with wet towels and fire extinguishers, which are in each compartment. And in the summer of 2016, a fire was artificially ignited in the cargo ship Cygnus undocked from the ISS to study the behavior of the flame in weightlessness.
Fires can be caused by short circuits in electrical systems, overheating of equipment, or chemical reactions.
How to put out a fire in zero gravity?
A fire can only spread if there is a constant supply of oxygen. On Earth, hot air rises and fresh air flows in to take its place. In weightlessness, combustion products are carried away by the ventilation system. If you turn it off, the fire quickly dies out. However, the situation can be complicated by strong smoke, sparks, and melting of materials.
In conditions of reduced gravity, conventional foam fire extinguishers are useless: foam is not thrown out in a directed stream, but is randomly distributed throughout the room.
University employee Dmitry Plak (Dmitriy Plak) and his colleagues decided to abandon the “reactive” installations in favor of sources of powerful sound. In experiments carried out on Earth, the researchers were able to put out the fire of a candle using a 55-Hz emitter with a power of 120 decibels.
Despite the fact that researchers still find it difficult to explain the mechanism of the phenomenon they discovered (according to them, sound waves cause a local pressure drop in the area of the flame, due to which there is a sharp decrease in the oxygen content in this area or a temperature drop causing the wick to fade), this the method works.
Now we need to come up with a means to protect the astronauts from the side effects of such a sonic fire extinguisher. After all, according to New Scientist SPACE, even 125 decibels is enough to stun an unprepared listener: his sensations will be comparable to those of a rock music lover who happened to be right in front of a full-size concert acoustics battery.