Following Near-Perfect Rehearsal, Artemis II Faces a Rollback
On February 19th this past week, NASA completed a near-perfect wet dress rehearsal (WDR) for the integrated SLS rocket and Orion spacecraft at Launch Complex 39B. However, on the evening of the 20th, an interrupted flow of helium to the rocket’s upper stage, the Interim Cryogenic Propulsion Stage (ICPS), prompted the need for additional work on the rocket. Unable to access the stage from the launch platform, NASA has made the difficult decision to roll the Artemis II stack back to the Vehicle Assembly Building (VAB). Rollback to the VAB heavily impacts Artemis II’s launch date, with the NASA Administrator now indicating a launch in March is off the table; the new launch date will be no earlier than April 1st.
This week’s WDR was a redo of the operation which was last conducted on the 2nd of February, during which excessive leaks of hydrogen fuel from the seals which mate the SLS rocket to its mobile launch platform prevented a completion of the test. In the time since, NASA workcrews replaced the offending seals at the pad, and conducted additional testing to prove the replacements worked. Thanks to this effort, the second WDR was completed almost entirely without issue. Leak rates remained within nominal levels for both the 4-inch and 8-inch seals between the rocket and pad, and the vehicle was able to conduct a full countdown to terminal count, including an additional (intentional) scrub and recycle into terminal count shortly afterwards.
Pending work such as the flight readiness review and activation of the flight termination system (FTS), NASA administrator Jared Isaacman confirmed yesterday a tentative launch date of March 6th for the Artemis II mission. To this end, temporary access platforms for accessing SLS’ FTS systems were successfully mounted to the tower yesterday. Unfortunately, these platforms must now be removed before the stack can return to the VAB. Weather restraints related to lifting the platforms in high speed winds will determine when the operation can take place. The Artemis II astronauts reentered their pre-flight quarantine at around 5:00 PM the same evening according to a post by mission commander Reid Wiseman on Instagram; they will likely exit their brief quarantine in the wake of this delay.
Isaacman clarified in a post on X that the issue “was an unexpected development during routine helium flow operations last evening,” which was not seen in either of the Artemis II WDRs. The helium bottles aboard the ICPS are used for engine pressurization in-flight, a hard requirement for launch. It is currently unclear what specific steps will be required at the VAB to address the issue, nor when the vehicle will be rolled back. In a followup post, Isaacman further detailed a few possible causes for the issue, including faults within the umbilical connection between the tower and the ICPS or the umbilical’s quick-disconnect interface. In regards to a possibility of a check valve failure, Isaacman stated such a fault “would be consistent with Artemis I, though corrective actions were taken to minimize reoccurrence on Artemis II.” Isaacman has indicated an additional press conference regarding Artemis II and future missions will occur in the coming week.
Space Scout will continue its coverage on the Artemis II prelaunch campaign as information becomes available.
