NASA will attempt once again this week to fully fuel its Space Launch System rocket with more than 700,000 gallons of liquid hydrogen and liquid oxygen as part of a full launch countdown rehearsal, known as a wet dress rehearsal (WDR).

The operation will begin with a call to stations at the Launch Control Center’s Firing Room 1 on Tuesday, February 17, and will culminate in actual fueling on Thursday, February 19, targeting a simulated launch time of 8:30 p.m. EST. This marks the second full-length fueling test following a “confidence test” conducted on February 12, during which teams loaded liquid hydrogen to assess newly replaced seals on the rocket’s core stage.

Although NASA encountered a new ground equipment issue that reduced hydrogen flow during the confidence test, officials said enough data was collected to meet key objectives. NASA Administrator Jared Isaacman said the repaired seals showed significantly lower leak rates compared to the first WDR.