NASA not planning another Artemis 1 countdown dress rehearsal – Spaceflight Now - Spaceflight Now

Forgoing another countdown rehearsal, NASA plans to return the first Space Launch System rocket to its assembly hangar at the Kennedy Space Center next week for a hydrogen leak repair and continued preparations for liftoff on the Artemis 1 moon mission.

With the countdown dress rehearsals complete, ground crews at Kennedy are preparing to roll the 322-foot-tall (98-meter) Space Launch System moon rocket to the Vehicle Assembly Building.

The return to the VAB will end the Wet Dress Rehearsal, or WDR, campaign was NASA moves closer to launch of the long-delayed Artemis 1 test flight around the moon, sources said late Wednesday.

The Artemis 1 launch will kick off an unpiloted demonstration mission of the powerful SLS moon rocket and the Orion spacecraft before future Artemis flights carry astronauts to the moon.

But a fourth dress rehearsal Monday proceeded deeper into the countdown, and the launch team filled the rocket with with its supply of 755,000 gallons of super-cold liquid hydrogen and liquid oxygen for the first time.

With the workaround in place to tell the ground launch sequencer sequencer computer to ignore the leak, the clock continued to T-minus 29 seconds, one second after control of the countdown handed off from the ground controller to an automated sequencer on-board the SLS moon rocket.

Despite the leak and the cutoff of the countdown before reaching T-minus 9 seconds, NASA officials said the dress rehearsal achieved most of its goals.

One of those was the startup of the hydraulic power units on the SLS solid rocket boosters, which should have occurred in the final 30 seconds of the countdown to drive the booster nozzles through a gimbal steering check with their thrust vector control mechanisms, according to John Blevins, the SLS program’s chief engineer at the Marshall Space Flight Center.

He the worst-case scenario of continuing without another rehearsal is a problem that causes an abort in the final seconds of the countdown on launch day.

Once the Artemis 1 rocket is back inside the Vehicle Assembly Building, the Artemis ground team will troubleshoot the leaky hydrogen connector detected Monday.

NASA not planning another Artemis 1 countdown dress rehearsal