NASA Pushes Artemis II Launch to March After Hydrogen Leak in Wet Dress Rehearsal
During Monday’s wet dress rehearsal at Kennedy Space Center, engineers halted fueling after detecting excessive liquid hydrogen buildup near the SLS core/tail service mast umbilical, stopping a countdown that had been loading more than 700,000 gallons of super-cold liquid hydrogen and liquid oxygen and filling only about half the core. The leak — along with earlier cold-weather delays — moved Artemis II out of the February window to no earlier than March, with the four-person crew monitoring from quarantine in Houston while launch teams apply workaround techniques developed after prior SLS hydrogen issues.
📌 Key Facts
- NASA has moved Artemis II off the February launch window; officials had warned the rocket must launch by Feb. 11 or slip to March, and now cite March as the earliest possible opportunity.
- The wet dress rehearsal countdown began at 8:13 p.m. ET Saturday; teams planned to load and hold more than 700,000 gallons of super‑cold liquid oxygen and liquid hydrogen and run a full simulated countdown and recycle drill.
- A recent cold snap and freezing temperatures at Kennedy Space Center already delayed the wet dress rehearsal and shortened the February launch window by two days, moving the earliest possible launch later than originally planned.
- During Monday’s fueling, engineers detected excessive hydrogen buildup near the base of the SLS core stage a couple of hours into loading, halting hydrogen flow with roughly half the core tank filled; hydrogen fills were stopped at least twice and propellant was held in the vehicle for several hours.
- The leak was traced to the tail service mast umbilical and the wet dress rehearsal countdown was terminated at T‑5:15 because of the liquid hydrogen leak.
- Launch teams have been applying workaround techniques developed after the first SLS launch in 2022 while engineers troubleshoot the leak.
- The Orion spacecraft had been powered up for several days because of the cold and engineers were preparing to charge its flight batteries as part of the test sequence.
- The four‑person Artemis II crew monitored the tests from quarantine at Johnson Space Center; NASA had said the crew would travel to Kennedy Space Center about six days before launch if the rehearsal succeeded, but Fox News reported the crew was released from quarantine and will reenter roughly two weeks before the next target launch date.
📰 Source Timeline (4)
Follow how coverage of this story developed over time
February 03, 2026
12:20 PM
NASA delays Artemis moon mission after finding fuel leaks in test run
New information:
- NASA has officially moved off the February launch window for Artemis II and now cites March as the earliest possible launch opportunity.
- NASA terminated the wet dress rehearsal countdown at T‑5:15 due to a liquid hydrogen leak at the tail service mast umbilical, after earlier high hydrogen concentrations in that area.
- The four‑person Artemis II crew, including commander Reid Wiseman, has been released from quarantine in Houston and will reenter quarantine roughly two weeks before the next target launch date.
- NASA confirms more than 700,000 gallons of super‑cold liquid hydrogen and oxygen were loaded and held for several hours during the test, but hydrogen fills had to be halted at least twice due to excessive build‑up near the base of the rocket.
February 02, 2026
9:44 PM
NASA rocket that will return astronauts to the moon hit by fuel leak during practice countdown
New information:
- During Monday’s wet-dress fueling at Kennedy Space Center, NASA detected excessive hydrogen near the bottom of the Artemis II SLS core stage a couple of hours into loading and temporarily halted hydrogen flow with only about half the core tank filled.
- The leak occurred as more than 700,000 gallons of super-cold hydrogen and oxygen were being loaded in a make-or-break dress rehearsal intended to mimic a full countdown to T‑30 seconds before engine ignition.
- NASA’s launch team began applying workaround techniques developed during the first SLS launch in 2022, which was also plagued by hydrogen leaks, while the four-member Artemis II crew monitored from quarantine at Johnson Space Center in Houston.
- NASA reiterates that the rocket must launch by Feb. 11 or the Artemis II mission will slip to March; a recent cold snap has already shortened the February launch window by two days.
12:49 AM
What to know about Artemis II's 'wet dress rehearsal'
New information:
- NASA started the Artemis II 'wet dress rehearsal' countdown at 8:13 p.m. ET on Saturday, leading into a Monday fueling and simulated launch countdown.
- Launch teams plan to load more than 700,000 gallons of liquid oxygen and liquid hydrogen into the SLS rocket Monday, then drain it and conduct a full countdown and recycle drill during a simulated launch window from 9 p.m. to 1 a.m. ET.
- Freezing temperatures at Kennedy Space Center delayed the wet dress rehearsal and pushed the earliest possible Artemis II launch from this coming Friday to no earlier than next Sunday, with additional opportunities in March and April.
- The Orion spacecraft has been powered up for several days due to the cold, and engineers are preparing to charge its flight batteries as part of the test sequence.
- NASA confirms the Artemis II astronauts are in quarantine in Houston and will not participate in the pad tests, and will travel to Kennedy Space Center six days before launch if the rehearsal goes well.
January 17, 2026