The dramatic rupture of a Space Launch System (SLS) liquid oxygen (LOX) tank this week marked completion of the core stage structural qualification test campaign. The cylindrical test article was pushed to its limits – and beyond – at NASA’s Marshall Space Flight Center in Huntsville, Alabama, to ensure readiness for the agency’s lunar Artemis missions. At 170% of maximum predicted flight loads, the tank spilled 197,000 gallons (746,000 liters) of water across the test stand.
“Our plan was to push the tank beyond its designed limits, gathering massive amounts of data until it eventually breaks,” said Luke Denney, Boeing’s SLS Qualification Test manager. “Confirming engineers’ prediction for how the structure will react and ultimately fail under these extreme conditions on Earth will prove the design is ready for space, while improving the design and development of current and future core stage vehicles.”
The controlled test was similar to the December 2019 test to failure of an SLS liquid hydrogen tank test article, also at NASA Marshall.
Hydraulic systems applied millions of pounds of force to the water-filled LOX tank to push, pull and bend the structure, simulating launch and flight pressure points. This test to failure used stronger forces than Boeing and NASA engineers expect SLS tanks to experience during their missions.
The tank successfully underwent 23 baseline tests earlier this year to identify potential buckling or cracking in the tank wall.
SLS structural qualification testing started in May 2017 with the stacked Interim Cryogenic Propulsion Stage, the Orion spacecraft stage adapter, and the launch vehicle stage adapter. Since then, four of the largest structures that make up the 212-foot tall core stage have been successfully tested. The Interim Cryogenic Propulsion Stage flight article, Orion spacecraft, and stage adapters are all at Kennedy Space Center in Florida, awaiting integration with the first SLS core stage and boosters.
Concurrent to structural testing, the first rocket’s core stage flight hardware is undergoing final testing at Stennis Space Center near Bay St. Louis, Mississippi. Green Run testing of the assembled SLS core stage for the Artemis I mission is an ongoing campaign through this fall, when its four RS-25 engines will fire up in launch configuration for the first time.
At NASA’s Michoud Assembly Facility in New Orleans, Boeing has also manufactured all the main core stage structures for what will be the first crewed launch, Artemis II.