NASA is moving ahead with a second wet dress rehearsal, or WDR-2, for the Artemis II mission. Launch controllers will take their positions in the Launch Control Center at 6:40 PM ET tonight (Feb. 17), kicking off a nearly 50-hour countdown sequence. The simulated launch window opens at 8:30 PM on February 19th and extends four hours.

The wet dress rehearsal will put the launch team through the full range of countdown operations — loading super-cold liquid hydrogen and liquid oxygen into the SLS core stage and upper stage tanks, running the countdown clock, demonstrating the ability to recycle after a hold, and draining the tanks to practice scrub turnaround procedures.

WDR-2 follows a partial fueling green run test on February 12th that revealed a suspected flow restriction in the liquid hydrogen ground support equipment. Over the weekend, teams swapped out a filter believed to be limiting hydrogen flow, reconnected the line, and began restoring proper environmental conditions inside the system. Despite the issue, NASA said the earlier test produced enough data to move ahead with this week’s full rehearsal.

The countdown sequence will include two runs through terminal count, the final ten minutes before launch. During the first run, operators will hold at T-1 minute, 30 seconds for up to three minutes before resuming the clock down to T-33 seconds. The team will then recycle back to T-10 minutes and execute a second terminal count, running to just inside T-30 seconds before ending the test. The exercise is designed to simulate real-world conditions, including scenarios where a launch might be scrubbed for technical or weather reasons.

While the Artemis II crew will not participate in the rehearsal, the Clouseout Team will head to Launch Pad 39B to practice Orion spacecraft final closeout operations, including closing the capsule’s hatches and completing final preparations for launch.

During WDR-1, closing the hatches proved challenging. After the closeout crew closed the Orion crew module hatch in the White Room, they began performing seal pressurization checks on the counterbalance assembly (the mechanism that assists in opening the hatch). During that process, a valve associated with Orion’s hatch pressurization was inadvertently vented, which depressurized the counterbalance assembly, which then had to be repressurized before work could continue. The Closeout Team will be on the clock during WDR-2 and are planning for a much better result.

No Launch Date…Yet

NASA has not committed to a formal launch date and won’t until the rehearsal is complete and engineers have reviewed the data. This cannot be stressed enough, despite what other media outlets are saying: NASA will not name a launch date until after WDR-2 is reviewed and the results are deemed sufficient to move forward to a Flight Readiness Review, where formal permission to launch Artemis II will be granted.

However, the agency has been quietly evaluating whether additional launch opportunities exist beyond the previously identified windows and has identified an extra date in early March. Agency managers have determined that March 6 is the earliest feasible launch date, accounting for the time needed to complete the second wet dress rehearsal, conduct thorough data reviews, and transition the pad, rocket, and spacecraft from testing to launch configuration.