No fooling: NASA targets April 1 for Artemis II launch to the Moon

“Engineers are assessing what allowed the seal to become dislodged to prevent the issue from recurring.”

NASA has fixed the problem that forced the removal of 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.”

NASA is not expected to return the SLS rocket and Orion spacecraft to the launch pad until later this month. Inside the VAB, technicians will complete several other tasks to “refresh” the rocket for the next series of launch opportunities.

This work will include activating a new set of flight termination system batteries for the rocket’s range safety destruct system, which would be used to destroy the vehicle if it veered off course during launch. Workers will also replace flight batteries on the SLS core stage, upper stage, and solid rocket boosters, and recharge the batteries on the Orion spacecraft’s launch abort system, NASA said. At the bottom of the rocket, crews will replace a seal on the core stage liquid oxygen feed line.

NASA has not said whether the launch team will conduct another countdown rehearsal after it returns to Launch Complex 39B at Kennedy.

The first of five launch opportunities in early April is on April 1, with a two-hour launch window opening at 6:24 pm EDT (22:24 UTC). There are additional launch dates available on April 3, 4, 5, and 6. Each launch period has about five potential launch dates after accounting for several constraints on the mission trajectory, which will carry the Orion spacecraft and four astronauts around the far side of the Moon and back to Earth.

Artemis II will be the first human spaceflight to the vicinity of the Moon since 1972 and is the first crew mission for NASA’s Artemis program, which aims to land astronauts on the lunar surface as early as 2028.

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Posted Wednesday 4 March 2026 at 11:49 am AEST (my time).

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