Rutherford is Rocket Lab’s family of electric-pump-fed liquid-oxygen/kerosene rocket engines. Battery-powered brushless DC motors drive the propellant pumps, replacing the gas-driven turbopump machinery used in many liquid rocket engines. The family includes sea-level first-stage engines and a vacuum-optimized upper-stage version. Electron combines nine sea-level engines with one vacuum engine; ratings and nozzle configuration belong to the specific model. Rocket Lab began engine development and test firing in 2013, and Electron first launched in 2017.