While fire has been with us as a species for so very long, we still don’t know everything about how it actually works. A recent discovery on the International Space Station is a reminder of this fact.
On Earth, flames burn in a teardrop shape, thanks to the wonders of gravity, air density, and the buoyancy of the burned by-products of a flame. In zero gravity, flames adopt a spherical shape, which makes for great flame experiments–and that’s what the FLEX experimental kit in the Space Station is for. In a recent experiment, scientists snuffed out small droplets of heptane that were alight. But the droplets kept burning, even though the flame had disappeared. The discovery means that so-called “cool” fire, which burns at a much lower temperature and has different chemical processes, can occur in zero gravity, just as “hot” fire can.
Though it seems weird, this experimental setup could have big implications on Earth wherever fuel is burned. For example, achieving a “cool” burn may allow for more efficient fuel consumption.
NASA and its international partners are keeping the ISS in orbit for roughly one more decade. It will serve as a base for more experiments like this one, as well as a training ground for the next class of astronauts, who could one day walk on Mars or visit an asteroid.