LIVE: Artemis II Wet Dress Rehearsal Coverage

Live updates for the Artemis II wet dress rehearsal will be published on this page. Live views of the launch pad and test are available online. All times are Eastern.

9:40 a.m.
Teams have started chilling down the liquid hydrogen and liquid oxygen lines for the SLS rocket’s core stage. This critical step cools the propellant lines ahead of loading super-cold liquid hydrogen and liquid oxygen into the core stage tank, which will eventually hold more than 700,000 gallons of liquid hydrogen and liquid oxygen.

The chilldown process ensures the hardware is conditioned for the extreme temperatures of cryogenic propellants, reducing thermal shock and safeguarding system integrity. Once complete, teams will transition to slow fill of liquid hydrogen and liquid oxygen, followed by fast fill later in the countdown.

9:35 a.m.
At approximately 9:27 a.m., the Artemis launch director gave the “go” to begin loading cryogenic liquid propellant into the SLS rocket.

NASA teams have completed final preparations and closeouts of the umbilicals connecting the mobile launcher to the SLS rocket and Orion spacecraft. The umbilicals provide power, communications, and fuel to different parts of the rocket and spacecraft, while additional accessories provide stabilization. During launch, each umbilical releases from its connection point, allowing the rocket and spacecraft to lift off safely.

Teams will begin slowly filling cryogenic propellant into the rocket beginning at L-9 hours 45 minutes in the countdown. Liquid hydrogen and liquid oxygen will flow into the rocket’s core stage and interim cryogenic propulsion stage tanks, topped off and replenished as some cryogenic propellant boils off. The team will also conduct leak checks to ensure loading proceeds as expected.

7 a.m.

The Artemis II wet dress rehearsal countdown continues as teams at NASA’s Kennedy Space Center in Florida began configuring the SLS (Space Launch System) rocket with gaseous nitrogen, an important step to mitigate fire hazards, protect spacecraft systems, and ensure mission safety ahead of fueling operations.

Technicians are replacing the ambient air with gaseous nitrogen, which is an inert gas that does not support combustion. By replacing air – which contains highly-combustible oxygen – with nitrogen, engineers can remove the oxidizer needed to sustain fire and dramatically reduce flammability risks in a launch environment filled with high-energy systems and propellants.

The step also includes an inerting purge that removes oxygen and prevents contaminants like moisture or particulates from entering sensitive systems on the rocket. This keeps propulsion and life-support hardware clean and stable and creates a non-reactive environment that protects hardware and minimizes chemical reactions during countdown and ascent.

Overnight, teams prepared fueling lines on the mobile launcher and powered up the SLS upper stage and boosters. In the next few hours, teams will activate the ground launch sequencer used for command and control during the countdown, and verify several systems are ready for fueling operations. NASA’s Artemis launch director, Charlie Blackwell-Thompson, will poll whether to give a “go” for tanking operations to begin.

While there won’t be a launch today, teams are targeting 8:30 p.m. EST as the opening of a simulated launch window. Following a first run through the countdown to 33 seconds before the simulated launch time, teams will recycle the clock to T-10 minutes and will resume until stopping at approximately T-30 seconds.