Two Flames
(Photo : NASA) On the left is the shape of flame on Earth and on the right is the shape of fire in zero-gravity environments.

In an experiment done to see how fire reacts in zero gravity, astronauts in the International Space Station conducted the Confined Combustion experiment which will help in improving fire safety aboard the space laboratory and future missions to the moon.


According to Dr. Paul Ferkul of the Universities Space Research Association, this experiment is necessary for the National Aeronautics and Space Administration to use this knowledge for improving material selection and fire safety strategies.

Here on land, a flame has a teardrop shape brought on by gravity which pulls colder and denser air down to its base displacing warm air. As warm air rises, it feeds fresh oxygen to the fire. However, in a zero-gravity environment, flames can be of spherical form or elongated depending on the external flows of air. In an article written by The Guardian, Ferkul explained that removing gravity eliminates the natural convection process and because of that the hot air is not going up because there is exactly no "up" in a zero-gravity environment. 

Ferkul and his team began the experiments on Christmas Eve, wherein they used some sort of fan to blow air into the box where they keep the flame ablaze to provide oxygen. In this experiment, two fuels are being tested: a fabric comprised of cotton and fiberglass and clear acrylic plastic sheets. The team is testing the difference in combustion rates in these materials when the airflow and box sizes vary. 

The team performed 15 experiments and was able to make the flame burn between 1 and 22 minutes. Ferkul also explained that burning stuff is enjoyable for astronauts. "They really enjoy the experiments because they're so hands-on. We get to talk to the astronauts while they're doing it," he narrated. 

Prior to this experiment, Ferkul and his team were also able to discover that some materials are more flammable on the moon because of lower buoyancy. The explanation behind it is because there are some materials that have really fast convection flow which enables it to extinguish the flames on Earth. However, that same convection flow will not be as fast on the moon. Sure, it can have enough speed to harvest fresh oxygen but not enough to blow out the fire. In these experiments which were meant to provide better predictions of how materials would react in a low gravity environment, Ferkul explains, "living on the moon is a different environment from the space station and Earth. The fires will behave differently there. There's reason to believe that fires could be more dangerous on the moon than on Earth." 

The team is optimistic that these recently-held experiments can provide new insights into the science of combustion especially in the chemistry of soot formation or how gas is able to radiate from flames. Ferkul explains that the equations are becoming easier to determine if buoyancy is out of the picture. "We can look at some underlying physics that is sometimes masked by buoyancy. Soot is a very difficult thing to unravel," he explains. NASA reports that further developments about the experiment will forego as SpaceX delivers new materials early this year.