Despite its infinite wonders, the final frontier is not the most hospitable environment for human explorers. On their journeys into outer space, astronauts require contained habitats in order to keep precious life-giving gases in their lungs and the blood in their bodies from vaporizing away. Unfortunately, it's possible for these habitats, including the International Space Station (ISS), to face sudden structural failure, from say, a fire. And because there's no Smokey Bear out there in Low Earth Orbit, it's up to NASA to prevent space fires. And they're doing so by lighting space fires.
The report of NASA's flame-on!-board a cargo spacecraft, which comes via Gizmodo, is only the latest in a series of fires that the space agency has started in space as a part of its Spacecraft Fire Experiment. The Spacecraft Fire Experiment (SAFFIRE) has been ongoing since June of last year, when NASA lit its first fire (SAFFIRE I) aboard the Cygnus cargo spacecraft. Since then, NASA lit another fire inside of Cygnus in November (SAFFIRE II), and then this final, third fire (SAFFIRE III) on June 4 of this year. They've all been very controlled, taking place on the unmanned and isolated Cygnus, and were nothing like what Sandra Bullock had to deal with in Gravity.
NASA is igniting these fires in order to study "large-scale flame growth" as well as "material flammability limits in long-duration microgravity." In microgravity—like that experienced aboard the ISS—fires behave very differently than they do here on Earth. Here on the surface of Earth a flame burns O2, and causes the hotter surrounding air to rise. Cooler, unburned air then fills in the vacuum left by the warmer, less-dense used air, giving the flame more fuel. In microgravity, this feeding process due to gravity and its consequent effects on pressure and density doesn't occur, which means flames in space burn cooler and slower. Without that pressure difference, they also form globes of flame, rather than the spears of flame we're used to in everyday life.
These tests need to be conducted because putting out a fire in space will require different resources than it does here on Earth. For example, in 1997 there was a fire aboard the Mir space station, and it was only contained after its source of oxygen fuel ran out. (Our own Kyle Hill spoke with one of the astronauts who had to deal first-hand with that experience.)
For SAFFIRE III, the experiment data is still in the process of being downlinked to NASA scientists here on Earth, but you can check out what the fires generally look like from the SAFFIRE I clip below.
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Images: Flickr / NASA Johnson