Not Your Ordinary Space Heaters: How Fire Is Different In Outer Space
Posted on: 7 January 2015
When there's a fire in space, astronauts can't just dial 911 and wait for a fire engine to race to their rescue. And even if the neighborhood firemen did have a way to get to space, they'd quickly discover that everything about fighting fires is a little different once you leave the earth's surface. Here are a few unique characteristics of dealing with fires in space:
What It Looks Like
When you think of a fire, you probably imagine something similar to what you see on top of a birthday candle. On earth, hot air rises, so combustible material is lifted away from the source of combustion, while burnable oxygen is pulled towards it, creating the familiar tear-drop shape. In zero-gravity, this buoyancy doesn't exist, so fires tend to burn as round blobs. Not only does the result look different from what you'd expect, it also acts differently, creating different quantities of dangerous byproducts such as smoke and soot.
How Hot It Is
Another complication? Fires actually burn at lower temperatures in space and require less oxygen to burn. This means fire-fighting compounds need to be used at higher concentrations to successfully suffocate a blaze.
How They're Detected
Because space vessels are oxygen-rich environments with limited resources, any fire on a spacecraft obviously can have serious consequences, making accurate and timely detection crucial. But where to put the detectors? On earth, smoke detectors are commonly located on ceilings because hot air rises. Not so in outer space. Instead, detectors are located throughout the craft, with special emphasis on ventilation systems.
How They're Extinguished
Thankfully, the International Space Station (ISS) has never had a fire emergency, but the Russian space station (The Mir) did have one significant incident during its time in service. In 1997 an oxygen generator caught on fire, ultimately consuming all the oxygen within the generator before burning itself out. While no one was injured in that incident, it did provide some useful information about how fires behave in space and helped shape the protocol currently in place on the ISS. If a fire were to occur, astronauts would proceed using the following steps:
- They would turn off the ventilation to the area in an attempt to slow the spread of the fire. Because fire can spread in all directions in space, slowing the fire is especially important both to minimize damage and to help determine the actual location of the fire source.
- After turning off the ventilation, astronauts would turn off power to any units in close proximity to the fire, again in an attempt to slow the fire and to prevent unnecessary damage.
- Finally, the astronauts would use fire extinguishers to battle the blaze. Fire extinguishers using CO2 are currently supplied on the space station.
As NASA and other space agencies make plans to take longer voyages further into space, the likelihood that astronauts will encounter fire while in space increases, making an understanding of how fire behaves in space and how best to combat it increasingly important.
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