NASA has fixed the problem that forced it to remove the rocket for the Artemis II mission from its launch pad last month, but it will be a couple of weeks before officials are ready to move the vehicle back into the starting blocks at Kennedy Space Center in Florida.

The 322-foot-tall (98-meter) rocket could have launched as soon as this week after it passed a key fueling test on February 21. During that test, NASA loaded the Space Launch System rocket with super-cold propellants without any major problems, apparently overcoming a persistent hydrogen leak that prevented the mission from launching in early February.

However, another problem cropped up just one day after the successful fueling demo. Ground teams were unable to flow helium into the rocket’s upper stage. Unlike the connections to the core stage, which workers can repair at the launch pad, the umbilical lines leading to the upper stage higher up the rocket are only accessible inside the cavernous Vehicle Assembly Building (VAB) at Kennedy.

Mission managers quickly decided to roll the rocket back to the assembly building for troubleshooting. The rocket returned to the VAB on February 25, and within a week, engineers found the source of the helium flow issue. Inspections revealed that a seal in the quick disconnect, through which helium flows from ground systems into the rocket, was obstructing the pathway, according to NASA.

Sealing the deal

“The team removed the quick disconnect, reassembled the system, and began validating the repairs to the upper stage by running a reduced flow rate of helium through the mechanism to ensure the issue was resolved,” NASA said in an update posted Tuesday. “Engineers are assessing what allowed the seal to become dislodged to prevent the issue from recurring.”