Jeff Bezos' Blue Origin space venture has successfully test-fired its BE-4 rocket engine, marking a key step in the development of its own New Glenn rocket as well as United Launch Alliance's next-generation rocket. GeekWire reports: ULA has been waiting for months to get good news about the BE-4 tests in West Texas. The company wanted to see a successful full-scale test before going ahead with plans to use the BE-4 engine on its Vulcan rocket, which is due to have its first flight in 2019. A Blue Origin competitor, Aerojet Rocketdyne, has been waiting in the wings with its AR1 engine, which ULA saw as a "Plan B" for the Vulcan in case the BE-4 faltered. Wednesday's initial hot-firing didn't reach full power or full duration, but the test's success nevertheless reduces the likelihood that ULA would turn to the AR1. The BE-4 engine, which uses liquefied natural gas as fuel, is built at Blue Origin's production facility in Kent, Wash., and shipped down to Texas for testing. Assuming that it's accepted for ULA's use, engine production will eventually shift to a factory in Huntsville, Ala. Engines for the orbital-class New Glenn rocket will go to Blue Origin's rocket factory in Florida, which is due to be completed by the end of this year.