HUGE progress! Engineers just completed welding the liquid hydrogen tank that will provide fuel for the first SLS flight in 2018. The tank measures more than 130 feet tall, comprises almost two-thirds of the core stage and holds 537,000 gallons of liquid hydrogen -- which is cooled to minus 423 degrees Fahrenheit. Credits: NASA/Michoud/Steven Seipel #NASA #spacelaunchsystem #engineering #technology #MAF #NOLA #Michoud