Fire in Space R
eno native and triathlete Sara McAllister has a lot going for her these days. The newly minted Berkeley mechanical engineering Ph.D. and current post-doc not only successfully participated in some 16 triathlons--including a grueling half-Iron Man Aquabike race, she also recently appeared on the History Channel series “The Universe,” published 13 academic papers on her NASA-funded research, and taught an upper level undergraduate “Fundamentals of Combustion” ME 140 class, which she called “a unique and eye-opening experience.” For the last two-and-a-half years, McAllister has been the lead graduate student in the NASA-funded UC Berkeley Microgravity Combustion Processes Lab in Hesse Hall, an ongoing collaboration between NASA, Berkeley mechanical engineering professor and associate dean of the Graduate Division Carlos FernandezPello, and his team of graduate students — this year, five of them women. Following President Bush’s January 2004 directive to complete the International Space Station, develop a new manned space exploration vehicle, and return to the moon “as the launching point for missions beyond,” the Berkeley team was tasked with building an experimental apparatus to test the flammability of materials in space environments. It’s one piece of a focused effort to reevaluate existing parameters and generate data that could lead to a new set of guidelines for preventing fires in space in next-generation spacecraft. For years it was widely assumed that fires in space would naturally suffocate themselves due to the lack of buoyant air currents in the absence of gravity. “But that’s not always the case,” says Professor FernandezPello. “We now know that combustible materials flame up more easily in a spacecraft environment.” Hot air does not rise in space, so the air around a piece of smoldering material stays put, insulating it, and causing it to heat up. What’s more, the low-velocity air from an air conditioner on a spacecraft helps fan these flames.
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The Graduate | Spring 2009
A Berkeley Lab Group is Focused on How to Prevent Disasters By Nancy Bronstein
It adds up to this, says McAllister: Where there’s a high concentration of oxygen [so astronauts can breathe] and low air flow, materials are even more flammable. The danger of fires in space has long been on NASA’s radar. There were the near misses aboard the Mir space station in 1997 when a faulty oxygen supply ignited, endangering the six-man crew, and aboard Apollo 13 in 1970 when an oxygen tank exploded. But the 1967 fire in the command module of Apollo I during a test and training exercise, which killed all three astronauts, was perhaps the greatest fire mishap in NASA’s history. It’s widely believed that among the many factors contributing to the disaster was the 100 percent oxygen used for the test (we breathe 21 percent oxygen at sea level), and the presence of flammable materials — some of them unexpected culprits, like Velcro — in the cockpit. Space fires may begin when electrical cables, circuit boards, or combustible materials overheat and begin smoldering. “Smoldering is a weak process,” says the professor. “It can go undetected for a long time, but once smoldering materials reach elevated temperatures