NASA loaded cryogenic propellant into the Space Launch System rocket and Orion spacecraft for a second time on February 19, 2026, at Kennedy Space Center’s Launch Complex 39B, pushing the countdown to T-33 seconds in a test that will determine when four astronauts fly around the Moon. The agency had targeted March as the earliest possible launch window after the first fueling attempt weeks earlier revealed hydrogen leak issues and a clogged filter, forcing hardware repairs that delayed the timeline. A clean result from this second wet dress rehearsal would clear the final major technical hurdle before NASA commits to a firm Artemis II launch date, potentially no later than April 2026.
What the Second Fueling Test Actually Proved
The second wet dress rehearsal validated far more than simple tank filling. Operators worked through a full sequence of line chilldown, slow fill, and fast fill for both the core stage and the Interim Cryogenic Propulsion Stage upper stage, then ran closeout crew hatch operations before entering the terminal count. The countdown reached T-33 seconds, the deepest point in the sequence, confirming that the rocket’s propellant systems, ground support equipment, and software interfaces could operate together under flight-like conditions. That milestone matters because it exercises the exact automated steps that would fire the engines on launch day.
The test also checked NASA’s ability to recycle the countdown and safely drain the tanks, a procedure the agency considers just as important as filling them. The official countdown notice described the rehearsal’s scope as validating cryo tanking, countdown, recycle capability, and draining tanks along with scrub procedures. For a crewed mission, proving that propellant can be safely removed if a launch is called off is not a formality. It is a crew-safety gate that must work flawlessly before astronauts ever board the vehicle, and the second rehearsal offered the first opportunity to demonstrate that full end-to-end sequence after recent repairs.
Hydrogen Leaks and the Repairs That Set Up This Attempt
The first wet dress rehearsal in early February succeeded in loading cryogenic propellant and safely draining the rocket, but operators detected higher-than-allowable hydrogen gas concentrations at the tail service mast umbilical. That interface, where ground plumbing connects to the rocket’s base, has been a persistent trouble spot. During Artemis I propellant loading years earlier, a hydrogen leak at the same tail service mast umbilical forced teams to stop flow and attempt to reseat the quick disconnect, delaying that mission’s schedule by weeks. The fact that the same general area produced problems again on Artemis II suggests the ground-side hydrogen plumbing remains a weak link in the SLS launch infrastructure.
Technicians responded by detaching rocket-to-ground interface plates and replacing two seals at the umbilical interface area. A separate issue surfaced during a partial fueling run on February 12, when a suspected ground support equipment filter reduced liquid hydrogen flow into the core stage. NASA replaced that problematic filter and re-established environmental conditions inside the vehicle before clearing the rocket for the second attempt. These were targeted fixes rather than design changes, which raises a practical question: if the same interfaces keep leaking, will NASA eventually need a broader redesign of the ground umbilical hardware, or can seal-and-filter swaps keep the system reliable enough for a crewed flight?
From Pad Arrival to Launch Window
The SLS rocket and Orion spacecraft arrived at Pad 39B in mid-January, beginning a month-long campaign of checkouts, fueling tests, and repairs. The first wet dress rehearsal produced enough data for NASA to send a team to the pad to close out Orion and confirm that the spacecraft’s systems survived the cryogenic environment. After reviewing those results in a briefing on the early findings, agency leaders said the mission remained on a path that could support a March launch opportunity, but they stressed that the schedule would depend on a clean second rehearsal and subsequent data review.
The countdown for the second attempt began on February 17 at 6:50 p.m. EST, with a simulated launch window set for February 19 at 8:30 p.m. EST. That two-day lead time mirrors the actual pre-launch timeline astronauts and ground crews would follow, giving engineers a realistic stress test of shift rotations, communication protocols, and decision gates. The full Moon visible behind the rocket during the test offered an unintentional reminder of the destination: this is the vehicle designed to carry humans around the Moon for the first time since Apollo 17 in 1972, and every rehearsal at Pad 39B is a dress rehearsal for that historic crewed flight.
What Stands Between Data Review and a Firm Date
NASA’s decision on when to launch Artemis II will not hinge on a single chart or a single manager’s judgment. The agency has laid out a process in which senior leaders for exploration systems, ground operations, and mission management jointly review the wet dress results before committing to a date. After the first fueling test, NASA emphasized in an update on the schedule outlook that the March window was an “earliest” opportunity, not a promise. That same caution is likely to guide the post-test review of the second rehearsal, especially given the history of hydrogen leaks at the pad.
In practice, managers now must weigh several factors: whether leak rates stayed within limits throughout the second test, whether the countdown automation behaved as expected down to T-33 seconds, and whether the recycle and drain procedures left the vehicle in a healthy state. They will also consider how much contingency remains in the ground systems and whether any follow-on work at the pad could introduce new risk. If the data show only minor issues that can be resolved with standard maintenance, NASA can move toward setting a specific launch date within the previously discussed March-to-April timeframe. If deeper concerns emerge, particularly with hydrogen handling or software logic in the terminal count, the agency may choose to stand down from the early windows and take additional time, accepting schedule pressure now to avoid compounding risk for the first crewed flight of the Artemis program.
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*This article was researched with the help of AI, with human editors creating the final content.
