Space is weird. A lot of phenomena act differently in space than they do on Earth. Fire is an especially important example because open flames on a spacecraft could spell disaster for missions and crew. Scientists want to know how fire burns in space so that better extinguishing equipment can be used in worst case scenarios. Unfortunately there’s only way to find out how fire acts in space. Yeah, risky isn’t it?
In 2009, the crew aboard the International Space Station started the Flame Extinguishing Experiment (FLEX) to learn how fire acts in the microgravity (almost no gravity) conditions in orbit. On Earth, hot gases rise from flames and combustion products are drawn away. In microgravity, these gases don’t rise at all. Instead, a different process called molecular diffusion draws combustion products away from the spherical flame 100 times slower than on Earth. The flames can burn at colder temperatures than on Earth and don’t require as much as oxygen. You can see the difference in this video:
That 2009 experiment was very useful and gave an idea of how to improve extinguishers on spacecraft. They’ll need to be much more concentrated for starters. But FLEX only ignited a single droplet of fuel. If something were to go drastically wrong on a mission, astronauts might have to deal with large fires spreading throughout their spacecraft. In order to learn how a big fire acts aboard spacecraft we’ll have to start a big fire. So that’s exactly what scientists are doing over the next few days.
The Cygnus spacecraft is currently visiting the International Space Station (ISS) to deliver supplies and take away garbage. It’s also carrying an experiment called Saffire, which will start the biggest ever intentional fire in space. It would be absurd to start a huge fire on the ISS so the scientists are waiting until the Cygnus spacecraft is on its way back to Earth. They will then start the fire remotely while it’s in orbit, record as much data as they can from the controlled burn, and then bring Cygnus down to Earth as it beams back the results. The box that contains the fire is about the size of a gym locker.
We’re supposed to feel more relaxed about the fact that the fire will take place after the satellite has left the ISS but the experiment will still be there with them. I’m sure the astronauts have that in mind as they move about inside Cygnus, collecting their supplies. The experiment is to become a standard practice on Cygnus journeys so scientists can test burns using different materials. The big question is will flames spread through a material quickly like on Earth or will microgravity slow it down? We’ll soon know the answer.
Clearly, the lives of astronauts just aren’t stressful enough. Thanks, NASA, for reminding us that there are a million things that can go wrong up there.
Main image © NASA