Space Station Sunday: Cool Flames And A Literal Space Race

This week on the International Space Station, research continued on an accidental but possibly very useful discovery concerning the properties of combustion. While working with the FLEX (Flame Extinguishing Experiment), an experiment designed to test methods of firefighting in microgravity, Earthbound scientific analyst Dr. Forman Williams noticed something odd. When heptane fuel was ignited in the ISS's special Combustion Integrated Rack (a securely sealed chamber in which fiery experiments can safely take place), it burned for some time, then appeared to die out. However, sensors measured that the fuel was still combusting invisibly between temperatures of 500K to 800K, with no flames in sight.

“We observed something that we didn’t think could exist,” Williams said.  "That’s right—they seemed to be burning without flames.  At first we didn’t believe it ourselves."

According to, the experiment was then replicated in various environments, in atmospheres similar to Earth’s, then in atmospheres infused with nitrogen, carbon dioxide, and helium.  The results showed a marked difference between the space flames and their combusting counterparts on Earth:  the invisible "cool flames" were more chilly than the visible ones found on Earth (temperature 1500K-2000K.)  Also, instead of the byproducts of soot, carbon dioxide and water, the "cool flames" emitted carbon monoxide and formaldehyde.

The cool flames are able to burn relaxedly in microgravity, as they form spheres and allow oxygen to approach slowly, letting chemical reactions occur at a more leisurely pace thanks to a lack of buoyancy which on Earth would have altered the heat and process of the combustion.  

Dr. Williams believes this new discovery may aid in creating cars with cleaner emissions.  It could alter the process of HCCI (homogeneous charge compression ignition) by compressing fuel and an oxidizer in the engine, rather than being ignited by a spark.
Williams explained, “The chemistry of HCCI involves cool flame chemistry. The extra control we get from steady-state burning on the ISS will give us more accurate chemistry values for this type of research.”

The results have been monitored by researchers from Cornell, NASA, Princeton, UC Davis, UC San Diego, the University of Connecticut, and the University of South Carolina.  A new round of testing, aptly and awesomely named the Cool Flame Investigation (band name alert!) will be underway soon.

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In scientific sporting news, NASA astronaut Steve Swanson will be in no danger of his bones succumbing to space atrophy, as he plans to run 31.3 miles on the ISS treadmill as part of a team for Colorado's Wild West Relay.  With five other teammates collaborating on the 200 mile, 2-day course from Fort Collins to Steamboat Springs, Swanson had been disappointed he'd miss the race while performing his duties as ISS Expedition 40 flight commander, but was given special permission by the Wild West Relay organizers to race from space.

As reported by, two other astronauts, Sunita Williams and Dottie Metcalf, are also on the team, dubbed "200 Miles, 20 Orbits, and 90 Shillings." The team name is indicative of the number of orbits the ISS will make during the race, as well as a nod to a local Colorado beer. If Swanson is successful, he will beat Williams' record of the farthest run in space, which was completed when she simulated (and finished) the 2007 Boston Marathon while in orbit.

While Swanson, 53, is an accomplished athlete who has previously run the relay in full gravity, he will have to make adjustments for this particular situation. A harness applying 140 pounds of pull at his shoulders is a necessary counterweight in microgravity, and sweat pools (rather than drips) in the unique ISS environment. If he can deal with the heft of the harness and keep the beads of sweat from hovering in his eyes, he will have completed (albeit more arduously) the same chunk of challenge as the rest of his ultra-marathoner team. And according to him, that's what's important.

“The best part of being in the relay is being part of a team," Swanson says. "Just like space flight.”

Commander Swanson and his running rig.  And you thought your daily jog was tough.

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