NASA Targets Artemis II Rollback For Feb. 24
CAPE CANAVERAL—NASA is aiming to return the Artemis II Space Launch System (SLS) rocket and Orion spacecraft to its assembly hangar on Feb. 24, pending weather and rollback preparations, the agency said Feb. 22.
NASA on Feb. 21 decided to return the 322-ft. stack to the Vehicle Assembly Building (VAB) to repair an issue with the rocket’s upper stage helium system, which stopped operating late Feb. 20. The Interim Cryogenic Propulsion Stage (ICPS) contains bottles of helium to purge the engines and pressurize its liquid hydrogen and liquid oxygen propellant tanks.
The work will bump the Artemis II launch from March to at least early April. The next window to meet mission requirements, including Earth-Moon orbital phasing, lighting and other factors—opens April 1. However, to be ready for that launch period, which closes April 6, the helium system repair and any additional servicing in the VAB would have to be accomplished in roughly half the time it took when another ICPS helium system issue, along with a fuel leak, spurred the first of three rollbacks during the 2022 Artemis I launch campaign.
NASA said the April 1-6 window remains viable “pending the outcome of data findings, repair efforts and how the schedule comes to fruition in the coming days and weeks."
The next launch window opens April 30.
The agency’s first SLS rocket and an uncrewed Orion spacecraft launched on Nov. 16, 2022—eight months after its initial rollout to Launch Complex 39B (LC-39B.) Transported onboard its mobile launcher, the stack made three trips back to the VAB—twice for technical reasons and once to avoid a hurricane—and several launch attempts before lifting off to begin NASA’s Artemis lunar exploration and development campaign.
Work following the first Artemis I rollback included resolving an ICPS helium valve issue discovered during a fueling test. The Artemis I SLS and Orion were returned to the launchpad six weeks later.
NASA has conducted two wet dress rehearsals for Artemis II, the latest of which concluded Feb. 19. Having resolved a hydrogen fuel leak that stymied the first practice countdown, NASA on Feb. 20 set March 6 as its targeted launch date.
Later that night, the Kennedy Space Center team was unable to get helium to flow through the vehicle. “This occurred during a routine operation to repressurize the system,” NASA Administrator Jared Isaacman wrote in a mission update.
NASA is using a backup method to maintain environmental conditions for the upper stage engines and the rocket, the agency noted.
Engineers have not yet identified the cause of the problem, but troubleshooting is focused on a filter in the umbilical between ground equipment and the flight hardware; a failed quick-disconnect umbilical interface; and/or a failed check valve onboard the vehicle. The latter problem “would be consistent with Artemis I, though corrective actions were taken to minimize re-occurrence on Artemis II,” Isaacman noted.
Regardless of the cause, accessing and remediating the issue can only be performed in the VAB.
The Artemis II crew—Reid Wiseman, Victor Glover, Christina Koch and Canada’s Jeremy Hansen—were released from a routine prelaunch medical quarantine Feb. 21 while the issue with their rocket is addressed. NASA has not said if another practice fueling run would be needed once the SLS returns to the launchpad.