Ariane 6 main engine hot and fired up

As close as you can get to the driving force of a rocket launch – this picture was taken during the combine hot-fire test (CTHF) of the Ariane 6 Vulcain 2.1 engine on 23 November 2023. 150 000 kg of supercooled oxygen and hydrogen were burnt up over eight minutes in the upgraded Vulcain’s longest test to date, matching the full engine burn of a real launch. Reaching 3000°C, hotter than the outer layers of supergiant stars, the engine fired flawlessly. Before the rocket propellant got to the nozzle it was put under extremely high pressure. It’s then burnt up in the combustion chamber and it is then that the nozzle converts the huge amount of energy from the high-pressure, extremely hot combustion products and turns it into kinetic energy by accelerating the gas to very high velocities. While doing this, the nozzle was also tested and swivelled, which, during a real launch would control the rocket’s trajectory