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 stage tank reaches full capacity.
Following topping, teams will move to replenish mode, keeping the ICPS tank at flight-ready levels into terminal count. Meanwhile, all other propellant tanks on SLS are in replenish mode.
A 24/7 live stream of the rocket at the pad remains online, as well as a separate feed to capture wet dress activities.
February 2, 2026
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