Supercold liquid oxygen is flowing into the tank of the Centaur upper stage for today’s launch. The Centaur’s single RL10 engine, built by Aerojet Rocketdyne, burns a combination of liquid hydrogen and liquid oxygen to generate thrust. The Centaur will perform three burns today to place NOAA’s GOES-R satellite into a transfer orbit that will be circularized by the spacecraft into an operational orbit, called geostationary or geosynchronous, more than 22,000 miles above Earth.