Vulcan Centaur rocket launching into space, illustration. The Vulcan Centaur is a United Launch (ULA) heavy-lift launch vehicle that will replace ULA's Atlas and Delta launch vehicles. Vulcan Centaur has been chosen for use by the US government's National Security Space Launch program. Measuring 61 metres length and weighing 546,700 kilograms, the launch vehicle's first stage is powered by two BE4 engines that burn methane. The Vulcan Centaur's initial flight is expected to launch in 2022.