450,000 gallons of water rushed onto Launch Pad 39B during a wet flow test today. During launch of #NASASLS rocket and @NASA_Orion​, the high-speed water flow will help protect the vehicle from extreme acoustics and temperature during ignition and liftoff. @NASA_go4launch pic.twitter.com/9MCBkQCX9f

— NASA's Kennedy Space Center (@NASAKennedy) December 20, 2017