NASA lines up WDR for SLS ahead of Artemis II

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Teams at the Kennedy Space Center are advancing preparations for the Artemis II mission, the first crewed flight of the Space Launch System (SLS) rocket and Orion spacecraft, with key milestones on track ahead of a critical wet dress rehearsal (WDR) test that is set for no earlier than January 31.

It has been a relatively smooth flow at 39B, following the successful rollout of the stacked SLS and Orion to the pad on January 17, 2026.

The upcoming wet dress rehearsal, a major prelaunch fueling demonstration, is targeted to begin as early as Saturday, January 31, simulating key elements of launch day without crew aboard.

This rehearsal involves loading more than 700,000 gallons of cryogenic propellants (liquid oxygen and liquid hydrogen) into the rocket, executing a full launch countdown sequence, and safely offloading the propellants.

Teams will conduct multiple “runs” to test the ability to hold, resume, and recycle the countdown at various points, particularly during the final 10 minutes, known as terminal count. The primary simulated launch is planned for 9 p.m. EST, though operations could extend to around 1 a.m. if additional time is required.

The first run starts about 49 hours before the simulated T-0, with teams manning stations through to T-1 minute 30 seconds, followed by a three-minute hold and resumption to T-33 seconds—where the vehicle’s automatic launch sequencer takes over. Teams will then recycle to T-10 minutes, hold, and proceed again to T-30 seconds in a second run.

These steps verify the launch team’s readiness and the ground systems’ performance under realistic conditions.

Recent accomplishments include the successful servicing of the SLS solid rocket boosters, where hydrazine was loaded into the aft skirts over the weekend.

Preparations for Orion continue, with technicians stowing items inside the crew module and conducted pyrotechnic work on the launch abort system. They also completed checkout of the core stage’s four RS-25 engines and pressurized a composite overwrapped pressure vessel in the spacecraft’s propulsion system.

Launch and Exploration Ground Systems (EGS) teams completed pad and mobile launcher connections, power-up, and initial testing by January 21.

The first half of Pad Pre-Stack Electrical Test (PSET) testing wrapped up on January 23, with the second set beginning on Sunday. Hypergolic propellant loading operations were underway as of January 24.

Preparations for the tanking test—closely related to the wet dress rehearsal—are scheduled to run from January 27 through January 30.

The day after rollout, significant winds caused minor tears to the thermal blankets on the SLS engines; those have since been repaired with no impact to the schedule.

With unusually cold weather forecast for Florida on Tuesday, January 27, teams are taking precautions to protect environmental control systems that maintain proper temperatures for Orion and SLS components.
Another issue that was swiftly resolved came via an evaluation of the emergency egress system, which revealed that the baskets for crew and pad personnel evacuation stopped short of the full descent path; brake adjustments have since been made to correct this.

Additionally, further sampling of Orion’s potable water system is planned after initial tests detected higher-than-expected levels of total organic carbon, ensuring the water meets safety standards for the crew.

The Artemis II astronauts—Commander Reid Wiseman, Pilot Victor Glover, Mission Specialist Christina Koch (all NASA), and CSA Mission Specialist Jeremy Hansen—entered quarantine in Houston on January 23 to minimize health risks ahead of launch.
SLS is currently targeting a launch no earlier than 9:41 p.m. EST on February 6, 2026 (2141 EST), within a two-hour launch window, though the overall opportunity spans several days in early February, with backups extending into April.

The wet dress rehearsal serves as a key decision point before any launch date can be set with any certainty. Depending on the results, NASA could opt to roll the vehicle back to the Vehicle Assembly Building for any necessary additional work.

A successful test paves the way for the targeted launch window—the first crewed journey to the vicinity of the Moon since Apollo 17 in 1972—for the approximately 10-day lunar flyby mission.

Lead photo: Jerry Pike for NSF.

The post NASA lines up WDR for SLS ahead of Artemis II appeared first on NASASpaceFlight.com.



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