Following the vent and relief test on the interim cryogenic propulsion stage (ICPS) liquid hydrogen tank, NASA teams have entered the topping phase of fueling liquid hydrogen. The vent and relief test verifies that the vent and relief valves operate correctly to maintain safe pressure levels inside the upper stage liquid hydrogen tank, while topping ensures the upper […]
Fueling of the SLS (Space Launch System) rocket is proceeding on all fronts, following earlier pauses on liquid hydrogen flows. Liquid hydrogen and liquid oxygen in the core stage are in the replenish phase. Liquid oxygen has also reached the replenish stage on the upper stage. Replenish mode keeps the tank at flight-ready levels by […]
NASA teams have completed filling the core stage of the SLS (Space Launch System) rocket with liquid hydrogen and transitioned to topping mode. Topping ensures the tank reaches its full capacity with super-cold liquid hydrogen chilled to minus 423 degrees Fahrenheit. Engineers continue to watch the leak at the interface of the tail service mast […]
Editor’s note: This blog post was updated at 4:09 p.m. EST on Feb. 2, 2026, to correct the status of liquid hydrogen operations at the time of posting. Ground teams have resumed loading liquid hydrogen operations into the core stage of the SLS (Space Launch System) rocket. Operations were stopped twice after leak rates at […]
After teams temporarily resumed fast fill of liquid hydrogen operations into the core stage, initial steps to correct the leak proved unsuccessful. The leak rate at the interface of the tail service mast umbilical continued to exceed the allowable limits. Liquid hydrogen filling operations on both the core stage and upper stage are paused as […]
Teams have started chilling down the lines used to feed liquid oxygen into the upper stage. Troubleshooting of liquid hydrogen loading into the core stage continues.
Teams have stopped the flow of liquid hydrogen through the tail service mast umbilical interface into the core stage after leak concentrations exceeded allowable limits. Stopping the flow allows engineers to perform troubleshooting procedures that were developed after Artemis I. Liquid oxygen continues to flow into the core stage, and liquid hydrogen continues to flow […]
As teams continue to fuel the SLS (Space Launch System) rocket’s core stage with liquid oxygen and liquid hydrogen, teams began propellant loading operations for the rocket’s interim cryogenic propulsion stage (ICPS), or upper stage. The launch control team is filling the ICPS with liquid hydrogen. The core stage liquid hydrogen and liquid oxygen tanks, meanwhile, are currently in fast fill. A 24/7 live stream of […]
Teams began chilling down the liquid hydrogen lines for the interim cryogenic propulsion stage of NASA’s SLS (Space Launch System) rocket. This critical step cools the propellant lines ahead of loading super-cold liquid hydrogen, chilled to minus 423 degrees Fahrenheit, into the SLS’s upper stage tank. The chilldown process ensures the hardware is properly conditioned for cryogenic temperatures, reducing thermal shock and […]
NASA teams have transitioned to fast fill of the SLS (Space Launch System) rocket’s core stage with super-cold liquid hydrogen, chilled to minus 423 degrees Fahrenheit and liquid oxygen chilled to minus 297 degrees. Fast fill rapidly loads hundreds of thousands of gallons of liquid hydrogen and liquid oxygen into their core stage tanks. During this process, […]
