NASA sets milestones on the path to Artemis II crew launch

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NASA has confirmed the upcoming milestones for its historic Artemis II mission—the first crewed flight of the Space Launch System (SLS) rocket and Orion spacecraft, sending four astronauts on a lunar flyby for the first time in over 50 years—with rollout and Wet Dress Rehearsal (WDR) to set the stage for a potential launch in February.

With the fully stacked vehicle now complete in the Vehicle Assembly Building (VAB), teams are finalizing preparations for rollout to Launch Pad 39B. NASA is targeting no earlier than Saturday, January 17, 2026, to begin the four-mile trek aboard the Crawler-Transporter 2, expected to take up to 12 hours.

The milestone date remains flexible, depending on the completion of technical closeouts, weather conditions, or any additional troubleshooting. However, optimism is high that SLS is now entering the final leg ahead of its second launch, following a lengthy processing flow.

Stacking for Artemis II began on November 20, 2024, immediately after NASA resolved issues related to Orion’s heat shield investigation following Artemis I.

This timing aligned with Administrator Bill Nelson’s announcement of a revised target date, initially April 2026, later refined to no later than that month, with potential for February for the flight of NASA astronauts Reid Wiseman (commander), Victor Glover (pilot), Christina Koch (mission specialist), and CSA astronaut Jeremy Hansen (mission specialist).

To the SLS and Orion team’s credit, this timeline has remained on target.

The stacking process unfolded in the VAB’s High Bay 3 on Mobile Launcher 1 (ML-1), with the first SRB segments stacked on November 20, 2024.

Stacking concluded in mid-February 2025 with the addition of the forward assemblies and nosecones. The twin boosters provide over 75 percent of SLS thrust at liftoff.

The core stage sailed from Michoud into KSC onboard the Pegasus barge in July 2024 and was turned vertical on December 10 in High Bay 2 for processing. Integration between the SRBs and core stage was completed on March 23, 2025.

This was then followed by the Launch Vehicle Stage Adapter (LVSA) being lifted and mounted on April 3, with bolting finished by April 12 (using 360 bolts). The Interim Cryogenic Propulsion Stage (ICPS) was integrated on May 1.

In late May 2025, NASA powered up the SLS core stage and SRBs for the first time, verifying systems, interfaces, engine controls, and booster thrust systems. Summer testing included checkouts and an engine swap. RS-25 engine E2063 was replaced with E2061 due to a hydraulic leak in the oxygen valve, completed in April while vertical.
With the launch vehicle complete, the focus switched to the Orion spacecraft that will fly the crew of four around the Moon.

Orion left the Neil Armstrong Operations & Checkout Facility around May 3–5, 2025, for propellant loading and fluid servicing at the Multi-Payload Processing Facility (MPPF). The launch abort system was installed and completed by late September 2025.

Orion rolled to the VAB on October 16, 2025, and was stacked atop the SLS in mid-to-late October, completing the full vehicle with the launch abort system.

Recent pre-rollout activities have included resolving minor issues, such as replacing a bent cable in the flight termination system (with testing completed over the weekend) and addressing a valve problem in Orion’s hatch pressurization system (successfully fixed and verified on January 5).

Teams also resolved leaks in ground support equipment used for loading gaseous oxygen into Orion for breathing air.

Signs that rollout was edging closer were confirmed by the roll of CT-2 to the VAB.

This huge, modified crawler has a long history with NASA and has made trips up and down the Crawlerway for many decades.

Once the integrated SLS rocket and Orion spacecraft arrive at Launch Pad 39B, engineers will immediately start pad integration tasks. This includes connecting essential ground support equipment—such as electrical lines, environmental control system ducts, and cryogenic propellant feeds.
Teams will then power up all integrated systems for the first time at the pad to verify that flight hardware functions properly in conjunction with the mobile launcher and ground infrastructure.

Following these checks, the Artemis II crew will perform a final walkdown at the pad to refresh themselves with the vehicle at the pad and the EES (Emergency Egress System) proceedures.

At the end of the month, NASA plans to conduct the critical wet dress rehearsal (WDR)—a full pre-launch fueling test without the crew aboard.

This rehearsal demonstrates the ability to load more than 700,000 gallons of cryogenic propellants (liquid hydrogen and liquid oxygen) into the SLS rocket, run through a launch countdown sequence, and safely offload the propellants. It will also check for leaks, which were a problem during the Artemis I pre-launch activities.
The test will feature multiple “runs” to practice holding, resuming, and recycling the countdown in the final minutes, known as the terminal count.

One run will simulate from approximately T-49 hours (when teams man stations) down to T-1:30, followed by a planned hold and resumption to T-33 seconds. A second run will recycle to T-10 minutes, hold, and continue to T-30 seconds.

The closeout crew—responsible for securing astronauts in Orion and closing hatches on launch day—will rehearse their procedures safely during this test.

NASA has incorporated lessons from Artemis I, with close attention to liquid hydrogen loading and updated procedures to manage gaseous nitrogen buildup between Orion’s crew module and launch abort system hatches. However, there are some unknowns, given that this core stage has not undergone a Green Run firing at Stennis, unlike ahead of Artemis I.

Should significant work be necessary post-rehearsal, NASA could roll back the vehicle to the VAB.

A successful wet dress rehearsal will lead to a Flight Readiness Review (FRR), where the mission management team evaluates all elements—hardware, infrastructure, and teams—before committing to a specific launch date.

The Artemis II launch window opens no earlier than Friday, February 6, 2026, targeting a lunar flyby trajectory that includes a high Earth orbit checkout, precise trans-lunar injection, a free-return path using the Moon’s gravity, limited eclipse periods, and a safe Earth entry profile.
Launch opportunities are constrained by orbital mechanics, resulting in roughly one-week windows followed by several weeks without viable dates. While exact daily opportunities may refine closer to the time, NASA is pursuing an early February attempt if all milestones proceed smoothly, with fallback periods extending into spring 2026.

“We are moving closer to Artemis II, with rollout just around the corner,” said Lori Glaze, acting associate administrator for NASA’s Exploration Systems Development Mission Directorate. “We have important steps remaining on our path to launch and crew safety will remain our top priority at every turn, as we near humanity’s return to the Moon.”

Lead image: SLS for Artemis I after arriving at 39B for Artemis I – via Stephen Marr for NSF.

The post NASA sets milestones on the path to Artemis II crew launch appeared first on NASASpaceFlight.com.



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