Setting fires in space in the name of safety
NASA just launched an Atlas V rocket with a supply-filled Cygnus spacecraft enroute to the International Space Station (ISS). Which is fine— the six astronauts living there will surely be happy to have fresh food, experiments and whatever being delivered. But the part of this launch that really counts is when the Cygnus spacecraft is done delivering supplies and becomes a big garbage receptacle, because this time around, NASA will use it as a big experimental dumpster fire. And while starting fires in objects moving at 17,000 miles-per-hour might seem like the kind of thing just meant to appeal to my inner 10-year-old, it’s actually being done in the name of safety and space exploration. Basically all we’re missing is some fireworks.
The experiment itself is called Saffire, and is actually only happening in a three by five foot box inside the Cygnus spacecraft. Because simply setting fire to any and all the waste from the space station would introduce too many variables for an useful experiment, the box will be setup in advance with a sheet cloth made from fiberglass and cotton. The box is also rigged with cameras and sensors, which will collect data for the computer in a secondary compartment. Once the Cygnus spacecraft is far enough away from the ISS, a remote control will ignite the cloth, reigniting it from the opposite end if it happens to go out. The recorded observations will then be transmitted to scientists on Earth, all before the Cygnus’ orbit decays enough for the entire spacecraft to be burnt up in our atmosphere over the ocean.
While astronauts on the ISS are involved in hundreds of experiments, those usually happen in the space station, not the garbage. The reason for this odd, disposable laboratory is the same reason for the experiment in the first place: fire safety. Fires are a huge concern in enclosed, fuel-rich spaces with limited oxygen, like space stations and space ships, which is why experiments involving flame have been extremely limited thus far on board the ISS. However, it’s better to be prepared for possible fires as much as possible, especially with plans to spend more time in space in the future.
Comprehending combustion in microgravity
The burning cloth in the Saffire is intended to then inform us about how fire might behave in microgravity. One hypothesis is that the microgravity will disrupt the spread of the fire, which is part of why plans were made for a secondary ignition. Later phases of the Saffire project will look at burning materials common to the space station, how smoke spreads in space, and eventually how to best but these fires out. Since it will be some time before we can hope for a fire in spacecraft to be anything short of a disaster, it appears that NASA will be needing to set fires in their garbage capsules for years to come. Fortunately, it shouldn’t be horribly long before we can find out just how neat weightless fire actually looks.
Source: Fire in the Hole: Studying How Flames Grow in Space by Nancy Smith Kilkenny, NASA News