J-2X Fuel Pump, the Heart of the J-2X Engine
The J-2X fuel pump is the heart of the J-2X engine. Much like the human heart pumps blood through the body, the fuel pump distributes liquid hydrogen through the engine. As the liquid hydrogen moves through the engine, it cools the main combustion chamber and nozzle, which are exposed to combustion gases that can reach temperatures upwards of 6,000-degrees Fahrenheit. The hydrogen is then mixed with the liquid oxygen and ignited to produce the thrust which will boost the launch vehicle.
Credit: Pratt & Whitney Rocketdyne