Residents of the International Space Station (ISS) are always behind incredible scientific experiences. As witnessed in this video, taken by the American astronaut, Reid Wiseman. Onboard the ISS in 2014, he published all sorts of photos and videos every day. Notably, the astonishing sequence which can be seen above: that of an inflammable product combusting.
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On Earth, everyone knows what to expect when we light a fire. Nevertheless, in a place where gravity exists only slightly or not at all, the flame behaves in a totally unexpected way by creating floating spheres of flames.
Combustion tests
For several years now, astronauts have regularly been conducting an experiment called the Flame Extinguishment Experiment or Flex. Several hundred attempts have been carried out in order to improve the understanding of the origin of flames and how to control them in microgravity. In other words, in an environment where the gravitational forces are very weak.
Despite what one might think, the flames burn well and truly in space. The experiment consists of setting alight a small drop of heptane in a special apparatus called the Flex Chamber Insert Assembly Apparatus which can be found on the ISS. Consequently, a sort of small spherical flame is created during the product’s combustion, before extinguishing gradually.
100 times slower
When a flame burns on Earth, hot gases rise from the fire creating a dynamic flow that draws oxygen into the flame and drives the products of combustion out. This phenomenon is the origin of what we know of terrestrial flames. Dan Dietrich, a scientist working on this project at NASA’s Glenn Research Centre, explained:
In the molecular diffusion of space, oxygen is drawn towards the flames and the products of combustion outside the flame at a rate 100 times slower than the dynamic flux on Earth.
In space, flames burn at a lower temperature and use less oxygen whose move randomly before becoming the source of the fire. Without the hot gases rising due to the lack of gravity, the flame takes the form a sphere, almost motionless because the oxygen supply is very low in the absence of convection. According to NASA:
The understanding of these processes could lead to the production of a safer spacecraft, as well as increased fuel efficiency for the engines running on liquid fuel on Earth.
Take a look at the video above to see the breathtaking footage in space for yourself...
