A fiber optic gas sensor under development at Boeing Co. of Seattle and at Intelligent Optical Systems Inc. of Torrance, Calif., promises increased safety in aerospace and automotive applications. The companies demonstrated the sensor on a Delta IV common booster core at NASA's John C. Stennis Space Center in Bay St. Louis, Miss. The system incorporates optrodes coated with a proprietary, hydrogen-sensitive substance. Light travels via optical fiber to the optrodes, and the color and intensity of the returning light indicate the presence and concentration of hydrogen. The researchers note that the sensor requires no power at the sampling point, so the risk of sparking a leak is eliminated. They predict that the system will find a place in vehicular hydrogen fuel cells under development, as well as in today's rockets.