Helium system on SLS upper stage-Officially known as the Interim Cryogenic Propulsion Stage (ICPS)– Both performed well during the Artemis II countdown rehearsal. “Yesterday evening, the team was unable to get helium flow through the vehicle. This occurred during a routine operation to pressurize the system,” Isaacman wrote.
A Space Launch System rocket lifts off from the Vehicle Assembly Building to begin the rollout to Launch Pad 39B last month.
Credit: Stephen Clark/Ars Technica
A Space Launch System rocket lifts off from the Vehicle Assembly Building to begin the rollout to Launch Pad 39B last month.
Credit: Stephen Clark/Ars Technica
Another molecule, another problem
Helium is used to purge the upper stage engine and pressurize its propellant tanks. The rocket is in a “safe configuration,” with a backup system providing purified air to the upper stage, NASA said in a statement.
NASA suffered a similar failure while preparing for the launch of the first SLS rocket on the Artemis I mission in 2022. On Artemis I, engineers traced the problem to a failed check valve on the upper stage, which required replacement. According to Isaacman, NASA officials are not yet sure whether Friday’s helium problem was caused by a similar valve failure, a problem with the umbilical interface between the rocket and the launch tower, or a malfunctioning filter.
In any case, technicians are unable to reach the problem area with the rocket on the launch pad. Inside the VAB, ground teams will extend work platforms around the rocket to provide physical access to the upper stage and its associated umbilical connections.
NASA said moving into rollback preparations now will allow managers to potentially preserve the April launch window “depending on the data findings, the outcome of repair efforts, and how the schedule plays out in the coming days and weeks.”
It is unclear whether NASA will conduct another fuel test on the SLS rocket after it returns to Launch Pad 39B, or whether technicians will perform any further work on the fragile hydrogen umbilical near the bottom of the rocket responsible for repeated leaks during Artemis I and Artemis II launch campaigns. Managers were pleased with the performance of the newly-installed seal during Thursday’s countdown demonstration, but NASA officials had previously said that vibrations from the rocket’s transport to and from the pad could damage the seal.
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