Prime contractor Boeing will roll out the Space Launch System (SLS) Core Stage 2 from the Michoud Assembly Facility (MAF) on July 16 and secure it to NASA’s Pegasus vehicle for a multi-day transport to the Kennedy Space Center (KSC) in Florida. This stage will control the launch of the Artemis II mission, which will send the Orion spacecraft with a four-person crew on a lunar flyby. The question is, when will that mission occur?
The launch of Artemis II was rescheduled in January this year for September 2025, but NASA is still verifying the results of Artemis I and monitoring the progress of the assembly and testing of the Artemis II Orion spacecraft. Currently, a verification of the overall situation is scheduled for mid-September this year to see if loading of the Artemis II SLS can begin.
Core Stage 2 Leaves Michaud
The stage was rolled out of the Michaux Vertical Assembly Building (Building 110) at dawn on July 16 and transported out of the building using NASA’s transportation equipment and Self-Propelled Modular Transporters (SPMTs).
After the entire stage had cleared the building and entered the runway area, the Boeing move team rotated the stage so that its front end was facing the area gate. The move went smoothly and faster than expected.
A ceremony to celebrate the completion of the stage by workers began as the stage left the site. By the time the celebration ended, the stage was out of sight and the Boeing mobile team had already completed nearly half of the journey, more than a mile, to the Pegasus ship. By noon, the core stage was on board the ship and stabilization work began.
Core Stage 2 will be loaded onto NASA’s Pegasus spacecraft on July 16. Courtesy NASA/Evan Desroches.
The rollout of the Artemis II core stage comes four and a half years after the rollout of the first unit. Disruptions caused by the COVID pandemic and the ongoing impact on the supply chain for parts for the vehicle have delayed deliveries from 2022 to the present.
Final integration testing of Core Stage 2 was completed in late January, but the stage was stored at Michoud in New Orleans for the first half of the year. NASA in January postponed Artemis II from late 2024 to September 2025 to allow for a better understanding of the Artemis I mission’s in-flight performance and to continue the mission’s ongoing work. Resolving other issues discovered during the production of hardware for future flights.
In early June, NASA and Boeing set a mid-July launch date and began the final weeks of preparation for delivery. “The weather looks good, the path looks good, and we still have work to do. [at Michoud]More rockets coming [the factory]”So we wanted to solve this,” Amit Kshatriya, NASA’s deputy assistant administrator for Moon and Mars programs, said during a media question-and-answer session at the July 16 launch.
The internal work platform was removed, the access doors to the intertank and engine sections were bolted down, covers were installed on the umbilical plates, engine heat shields, antennas and other external equipment, and the scaffolding surrounding the vehicle was moved out of the way.
This allowed the stage to rotate about its long axis to facilitate Thermal Protection System (TPS) work and installation of fairings on the engine section and boattail prior to shipment. After all work in the final assembly area was completed, the stage was moved into the transfer aisle in Building 110.
The Artemis II core stage was rolled out of final assembly at MAF on July 6 in preparation for final shipment. Image courtesy of NASA/Michael DeMocker.
In the transfer corridor, two large cranes inside the building lifted the stage so that the factory’s transport and handling equipment could be swapped for the outdoor, land-based versions. A temporary weather cover was also installed on the front of the stage, over the forward skirt. This is different from the white weather cover used for the first core, and will be used for the first Exploration Upper Stage (EUS) flyby.
Both the core stage and first flight EUS will undergo the Green Run design validation campaign at Stennis Space Center and remain outdoors on the B-2 Test Stand for several months — in contrast, the Artemis II core stage is expected to spend only a few hours outdoors in this configuration.
When will the Artemis II Core Stage be stacked?
Pegasus will be towed from New Orleans to the Gulf of Mexico, around the Florida peninsula, and finally to Port Canaveral and the Kennedy Space Center. The journey is expected to take about a week, and for safety reasons NASA doesn’t normally provide progress updates on the journey.
Once the stage arrives at the Kennedy Space Center Turn Bay dock in Pegasus, Boeing will formally transfer ownership to Exploration Ground Systems (EGS) for launch processing. Once at Kennedy Space Center, only two mating adapters for the SLS need to be transported to the launch site: the Launch Vehicle Stage Adapter (LVSA) and the Orion Stage Adapter (OSA).
The Solid Rocket Booster (SRB) hardware is stored at the Rotational Processing and Surge Facility (RPSF) and the Interim Cryogenic Propulsion Stage (ICPS) is stored at nearby Cape Canaveral Space Force Station (CCSFS), both of which are ready to support stacking as soon as the decision is made.
The SLS program continues to analyze the rocket’s performance during the Artemis I launch on Nov. 16, 2022, updating models and making refinements. NASA and Boeing plan to complete work at Kennedy Space Center to eliminate an in-flight anomaly (IFA) identified by vibrations measured in the core stage and the release of debris during launch.
“[Boeing did] Most of the work at Michaud [and] We’re going to end it [Vehicle Assembly Building] “When we bring baggage into Kennedy, there are chances that anomalies will arise in the transfer aisles and high bays,” Kshatriya said, “so we should be able to address those anomalies before we start loading.”
Additionally, EGS and prime launch processing contractor Jacobs will perform final stack preparations and install Flight Termination System (FTS) components in the stage’s system tunnel.
The Artemis II Orion spacecraft was moved into the altitude chamber for vacuum testing on June 28. Image courtesy of NASA/Rad Sinyak.
Final assembly and testing of the Orion spacecraft for Artemis II marks the first complete crewed spacecraft assembly and a critical step in beginning launch preparations and ultimately preparing for launch next year. The spacecraft recently returned to the altitude chamber in the Neil Armstrong Operations Checkout Building at Kennedy Space Center to begin vacuum testing.
The tests were scheduled to begin in late June shortly after installation in the altitude chamber and were expected to take approximately two weeks to set up, run and conclude. Updates were planned for the spacecraft after it was removed from the chamber following the completion of the tests. The investigation and findings regarding the performance of the Orion heat shield during Artemis I re-entry, as well as recommendations for corrective actions, are also currently under independent review.
Additionally, Mobile Launcher 1 continues integrated systems verification and validation testing at Pad 39B. Mobile Launcher 1 should return to VAB High Bay 3 at KSC in preparation for loading of the Artemis II rocket.
The Moon to Mars Program Office will hold a checkout review near the end of the summer to determine when to begin stacking, starting with the SLS booster. “The decision to stack will depend on many factors,” Kshatriya noted.
“Obviously, when you launch the booster, there’s a countdown that starts for the propellant transfer, so we have to do this intelligently and manage it in conjunction with the spacecraft processing. [That] It’s going well, they’re working really hard, but all roads are pointing towards a mid-September time frame. [to review progress and make a decision].”
(Main image: The Artemis II core stage rolls out of the Michoud Assembly Facility on July 16. Courtesy of NSF’s Philip Sloss.)
