NASA delays Artemis-II launch window to March as wet dress rehearsal paused over hydrogen leak

NASA Administrator Jared Isaacman said on Tuesday that the February launch window for the Artemis-II mission has been pushed to March. The announced came after the critical wet dress rehearsal hit a pause over a hy drogen leak.

"With the conclusion of the wet dress rehearsal today, we are moving off the February launch window and targeting March for the earliest possible launch of Artemis II," Isaacman posted on X.

Key test terminated

NASA terminated Artemis-II's crucial wet dress rehearsal due to a hydrogen leak in its SLS (Space Launch System) rocket, calling into question how soon astronauts could take off for a trip around the moon.

The space agency conducted a crucial fueling test on Monday, February 2, with the Artemis II mission's SLS rocket.

More than 700,000 gallons (2.65 million liters) of cryogenic liquid hydrogen (LH2) and liquid oxygen (LOX) were loaded into the two-stage vehicle on Pad 39B at Kennedy Space Center (KSC) in Florida.

But the team had to stop loading LH2 into the SLS core stage twice to deal with leaks. They, however, managed to troubleshoot the issue in relatively short order and top up the rocket's enormous tanks, Space.com reported.

The Artemis 1 launch campaign was delayed repeatedly by LH2 leaks and other issues.

NASA says…

In a statement on Tuesday, NASA said, “The Artemis II wet dress rehearsal countdown was terminated at the T-5:15 minute mark due to a liquid hydrogen leak at the interface of the tail service mast umbilical, which had experienced high concentrations of liquid hydrogen earlier in the countdown, as well.”

“The launch control team is working to ensure the SLS (Space Launch System) rocket is in a safe configuration and begin draining its tanks,” the space agency said.

NASA had said earlier that engineers will have a close eye on propellant loading of liquid hydrogen and liquid oxygen into the rocket, after challenges encountered with liquid hydrogen loading during Artemis I wet dress rehearsals.

What exactly happened?

NASA Administrator Jared Isaacman said that during the test, teams worked through a liquid hydrogen leak at a core stage interface during tanking, which required pauses to warm hardware and adjust propellant flow.

“All core stage and interim cryogenic propulsion stage tanks were successfully filled, and teams conducted a terminal countdown to about T-5 minutes before the ground launch sequencer halted operations due to an increased leak rate,” he posted on X.

He added, “Additional factors included extended Orion closeout work, intermittent ground audio dropouts, and cold-weather impacts to some cameras, along with the successful demonstration of updated Orion closeout purge procedures to support safe crew operations.”

What is Wet dress rehearsal?

It is a prelaunch test to fuel the rocket. During wet dress, teams demonstrate the ability to load more than 700,000 gallons of cryogenic propellants into the rocket, conduct a launch countdown, and practice safely removing propellant from the rocket without astronauts onsite.

During the wet dress rehearsal, the closeout crew will close the spacecraft’s hatches, verify hatch seals, check environmental conditions, and confirm all systems are ready for the next steps in the countdown.

Additional wet dress rehearsals may be required to ensure the vehicle is completely checked out and ready for flight.

If needed, NASA may rollback SLS and Orion to the Vehicle Assembly Building for additional work ahead of launch after the wet dress rehearsal.

Why is a wet dress rehearsal crucial?

A successful wet dress rehearsal is necessary ahead of the actual launch. The test is vital for validating that the rocket and ground systems are safe for the first human flight around the Moon in 50 years.

It was earlier said that the launch of the Artemis II mission with four astronauts depended on the successful wet dress rehearsal and weather conditions, among other factors.

“After the wet dress rehearsal, the mission management team will assess the readiness of the systems and confirm a launch date,” NASA Artemis said in a post on X.

All eyes are now on NASA's press conference on Tuesday at 12 pm EST (10:30 pm IST), about the wet dress.