NASA Stennis Space Center engineers conducted a successful cold-flow test of an RS-84 engine component Sept. 24. The RS-84 is a reusable engine fueled by rocket propellant - a special blend of kerosene - designed to power future flight vehicles. Liquid oxygen was blown through the RS-84 subscale preburner to characterize the test facility's performance and the hardware's resistance. Engineers are now moving into the next phase, hot-fire testing, which is expected to continue into February 2004. The RS-84 engine prototype, developed by the Rocketdyne Propulsion and Power division of The Boeing Co. of Canoga Park, Calif., is one of two competing Rocket Engine Prototype technologies - a key element of NASA's Next Generation Launch Technology program.