Editor’s note: This story has been updated to include one NASA announcement that Artemis II’s targeted rollback will now take place on Wednesday (February 25), a day later than originally planned, due to windy weather.
NASA has delayed its historic Artemis II lunar mission again after the space agency’s lunar rocket experienced a problem with helium flow overnight Friday (February 20-21).
To solve the problem, NASA has announced that it will take the rocket and Orion spacecraft from a launch pad at the Kennedy Space Center (KSC) in Florida and roll them back to KSC’s Vehicle Assembly Building as early as Wednesday (February 25).
“Returning to the vehicle assembly building at Kennedy is necessary to determine the cause of the problem and fix it,” a NASA spokesperson said in a statement.
The The Artemis program has experienced a number of problems and setbacks, including a number of hydrogen leaks. Still, this latest delay will be particularly disappointing for space enthusiasts who were hoping to see Artemis II fly after it appeared to clear a critical driving test Thursday (February 19).
NASA said the SLS systems performed well during Thursday’s wet dress rehearsal, as staff demonstrated the systems’ ability to safely fuel more than 700,000 gallons (2.6 million liters) of cryogenic propellants — supercold liquid hydrogen fuel and liquid oxygen oxides — and completed a simulated launch. The test’s success led to an exuberant NASA press conference on Friday (February 20).
“Every night I look up at the moon and I see it and I get really excited because I can feel her calling us and we’re ready.” Lori GlazeNASA’s Moon to Mars program manager said at the conference. “The excitement for Artemis II is really starting to build, we can really start to feel it. It’s coming.”
But Artemis’ wings were soon clipped the same day, after a problem with the helium system on the rocket’s upper stage meant “the team was unable to get helium flow through the vehicle,” NASA Administrator Jared Isaacman wrote in an update on X Saturday. Helium is used on the SLS upper stage (officially called the Interim Cryogenic Propulsion Stage) to purge the engine and pressurize the propellant tanks.
As an update to my previous post. – The ICPS helium bottles are used for cleaning the engines, as well as for LH2 and LOX tank pressurization. Systems worked correctly during WDR1 and WDR2.- Last night the team was unable to get helium flow through the vehicle. This… https://t.co/Qte3nEXwQb21 February 2026
NASA is currently investigating potential causes of the helium flow problem, which includes looking at the interface between the ground and the rocket lines used to route helium, as well as examining a filter between the ground and the rocket and a valve in the upper stage. The agency said it is also reviewing data from Artemis I, the unmanned predecessor to Artemis II, which had a problem with helium-related pressurization before its 2022 launch.
The Artemis II SLS rocket returned to the vehicle assembly building (VAB) until the end takes off in November 2022, so this latest development doesn’t mean Artemis II won’t fly. NASA hopes that the return will have a short processing time, to keep the April launch window open. However, space travel is a difficult and delicate process, and there is no guarantee that Artemis II will fly in April either. Additional Artemis II updates are expected this week.
“The quick work to begin preparations to roll the rocket and spacecraft back to VAB potentially preserves the April launch window, pending the outcome of data discovery, repair work and how the schedule plays out in the coming days and weeks,” NASA wrote in its update.
Artemis II will be a historic mission if and when it finally takes off, marking the first time NASA has sent humans back to the moon in more than 50 years and the first time ever that NASA sent a woman and a black man as part of a lunar crew.
NASA will use the 10-day orbit around the moon to test systems and gather data ahead of the Artemis III mission, which aims to land astronauts on the moon in 2028. NASA wants to establish a long-term presence on the moon with the Artemis program and eventually turn the moon into a springboard for sending astronauts to Mars.
The Start windows in April for Artemis II includes April 1, April 3 to 6, and April 30. The assignment is intended to start on 30 April at the latest.
