 In a related application, sodium azide, the gas-forming agent in air bags, is produced from hydrazine by reaction with sodium nitrite.Hydrazine is also used as a propellant on board space vehicles, such as the NASA Dawn probe to Ceres and Vesta, and to both reduce the concentration of dissolved oxygen in and control pH of water used in large industrial boilers.The F-16 fighter jet, NASA Space Shuttle, and U-2 spy plane use hydrazine to fuel their emergency power units.