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The Gore Weld Tool( foreground) and Circumferential Dome Weld Tool( background) used to fabricate dome segments for the SLS liquid hydrogen and oxygen core stage tanks via vertical friction stir welding operations at NASA’ s Michoud Assembly Facility in New Orleans. Credit: Ken Kremer
components together in the Vertical Assembly Center by a process known as friction stir welding. The rings connect and provide stiffness between the domes and barrels.
The LH 2 tank is the largest major part of the SLS core stage. It holds 537,000 gallons of super chilled liquid hydrogen. It is comprised of five barrels, two domes, and two rings.
The LOX tank holds 196,000 pounds of liquid oxygen. It is assembled from two barrels, two domes, and two rings and measures over 50 feet long.
The material of construction of the tanks has changed compared to the ET.
“ The tanks are constructed of a material called aluminum 2219 alloy,” said Whipps.“ It’ s a ubiquitously used aerospace alloy with some copper but no lithium, unlike the Shuttle superlightweight ET tanks. This alloy is heavier but does not affect our payload potential.”
“ The intertanks are the only non welded structure. They are bolted together and we are manufacturing them also. It’ s much heavier and thicker.”
The entire SLS core stage will tower more than 212 feet( 64.6 meters) tall and sport a diameter of 27.6 feet( 8.4 m).
The total weight of the empty core stage will be 188,000 pounds, and 2.3 million pounds when fully loaded with propellant. The empty ET weighed some 55,000 pounds.
Considering that the entire Shuttle ET was 154- feet long, the 130-foot long LH 2 tank alone isn’ t much smaller and gives perspective on just how big it really is as the largest rocket fuel tank ever built.
Every fuel tank welded together from now on after this series of confidence and qualification LOX and LH 2 tanks will be actual flight article tanks for SLS launches. What’ s ahead for the SLS-2 core stage?“ We start building the second SLS flight tanks in
October of this year,” Nesselroad stated. The maiden test flight of the SLS / Orion is targeted for November 2018 and will be configured in its initial 70-metric-ton( 77-ton) Block 1 configuration with a liftoff thrust of 8.4 million pounds – more powerful than the Saturn V moon rocket. Although the EM-1 flight in 2018 will be uncrewed, NASA plans to launch astronauts on the EM-2 mission slated for between 2021 and 2023.
The exact launch dates fully depend on the budget NASA receives from Congress, who is elected President in the upcoming election, and whether they modify NASA’ s objectives.
“ If we can keep our focus and keep delivering, and deliver to the schedules, the budgets and the promise of what we’ ve got, I think we’ ve got a very capable vision that actually moves the nation very far forward in moving human presence into space,” said William Gerstenmaier, associate administrator for the Human Exploration and Operations Mission Directorate at NASA Headquarters in Washington.
“ This is a very capable system. It’ s not built for just one or two flights. It is actually built for multiple decades of use that will enable us to eventually allow humans to go to Mars in the 2030s.”