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.
10:18 p.m.
The Artemis II wet dress rehearsal ended today at 10:16 p.m., concluding as planned at T-29 seconds in the countdown.
NASA will hold a media briefing about the test at 11 a.m., Friday, Feb. 20, which will stream on the agency’s website. A 24/7 live stream of the rocket at the pad remains online.
10:07 p.m.
NASA teams officially entered the second round of terminal countdown, or the final ten minutes of today’s Artemis II wet dress rehearsal countdown after successfully recycling the clock back to T-10 minutes. The new T-0 is set for 10:17 p.m.
9:23 p.m.
Editor’s Note: A previous post below from 8:44 p.m. was removed unintentionally:
The terminal countdown was paused due to a booster avionics system voltage anomaly, but resumed and continued to the planned recycle point. The team is now resetting the countdown as planned.
9:04 p.m.
After running through terminal count for the Artemis II wet dress rehearsal, the launch team paused the clock at T-33 seconds in the countdown. Teams are now reconfiguring and replenishing the liquid hydrogen and liquid oxygen systems, in order to recycle back to the T-10 minute mark and perform another run of terminal count.
As planned, the count was held for three minutes before beginning the recycle.
Having another opportunity to run through terminal count allows the team to practice the recycle operations, which include safing the SLS rocket and getting the propellant tanks back to replenish mode to be ready for terminal count again. The entire recycle process lasts approximately 60 to 90 minutes.
8:39 p.m.
The crew access arm has been retracted. The launch abort system would be available to pull the crew to safety in the event of an emergency on the launch pad beginning 5 minutes 25 seconds before launch.
8:32 p.m.
NASA teams have now officially entered the final ten minutes of today’s Artemis II wet dress rehearsal countdown known as terminal count after Charlie Blackwell-Thompson, NASA’s Artemis launch director, gave the “go” to proceed toward the simulated T-0 time of 8:42 p.m.
During terminal count, automated systems take control of countdown operations, final checks of flight computers, engine bleed systems, and ground support equipment occur, and the rocket transitions to internal power, and the countdown proceeds toward simulated engine start.
Terminal count is designed to confirm that all systems can perform flawlessly under launch conditions, ensuring readiness for Artemis II – the first crewed mission of the Artemis program.
During this first terminal count run, the team will pause at T-1 minute and 30 seconds for up to three minutes, then resume until T-33 seconds before launch and pause again. After that, they will recycle the clock back to T-10 minutes and conduct a second terminal countdown to approximately T-33 seconds before ending the sequence. This process simulates real-world conditions, including scenarios where a launch might be scrubbed due to technical or weather issues.
8:29 p.m.
The launch director has extended the T-10 minute hold to allow for time to complete final preparations for the terminal countdown of today’s wet dress rehearsal, including bringing the core stage engine section temperature into the necessary range for launch. It is currently just shy of the temperature that would be required if SLS were planning to launch, but engineers expect it to rise shortly.
A new simulated T-0 time will be set once the temperature has risen into the correct range
7:02 p.m.
NASA’s Artemis II closeout crew has completed its critical tasks and departed NASA Kennedy’s Launch Complex 39B during the Artemis II wet dress rehearsal.
The departure of the closeout crew marks the transition to the final countdown phase of the test, ensuring the launch pad is clear and safe for simulated liftoff procedures. Their work validates launch day protocols and confirms Orion and the SLS (Space Launch System) rocket are configured for flight readiness.
With the pad secured, teams will continue monitoring fueling operations and prepare for wet dress rehearsal terminal count: the final ten minutes of the countdown.
6:17 p.m.
NASA teams have closed the launch abort system hatch during the Artemis II wet dress rehearsal, simulating final launch day procedures. The launch abort system hatch provides access to the Orion crew module through the abort tower and must be securely sealed to ensure crew safety during ascent.
Closing the launch abort system hatch is a critical milestone that confirms the spacecraft is fully configured for flight. The hatch is designed to protect astronauts in the event of an emergency during launch, and proper hatch integrity ensures the system can perform as intended.
With the hatch secured, the closeout crew validates mechanical seals, verifies environmental conditions, perform leak checks, and confirms readiness for the next steps in the countdown sequence.
Next up, the closeout crew will depart the launch pad once its work is completed.
4:40 p.m.
As part of the Artemis II wet dress rehearsal, NASA teams have closed the Orion crew module hatch inside the White Room at Launch Pad 39B. This step simulates launch day procedures, ensuring the spacecraft is sealed and ready for launch. The Artemis II astronauts are not participating in today’s rehearsal, but the closeout crew simulated strapping them into their seats.
Closing the hatch is a critical milestone that demonstrates Orion’s readiness for flight and validates procedures for the first crewed Artemis mission around the Moon. The closeout crew will next close the launch abort system hatch.
3:55 p.m.
NASA’s Artemis II closeout crew is en route to the White Room inside the crew access arm at Launch Pad 39B. This specialized team is responsible for securing the Orion spacecraft and ensuring all access points are properly configured before simulated crew ingress operations.
The White Room is the environmentally controlled area at the end of the crew access arm, providing a clean and safe space for astronauts to enter Orion on launch day. During the wet dress rehearsal, the closeout crew will close the spacecrafts’ hatches, verify hatch seals, check environmental conditions, and confirm all systems are ready for the next steps in the countdown.
In addition, the pad rescue team will be positioned to respond immediately in the unlikely event of an emergency, ensuring safe evacuation procedures for pad personnel. Their presence ensures that all operations meet stringent safety standards as the SLS (Space Launch System) rocket and Orion spacecraft move closer to flight readiness. These teams are essential for mitigating risk and supporting the complex choreography of Artemis II’s prelaunch activities.
3:32 p.m.
Now in a 1-hour, 10-minute hold during today’s wet dress rehearsal countdown, all stages of the SLS rocket remain in replenish mode.
NASA’s pad rescue and closeout crew teams are moving to their staging area before heading to Launch Complex 39B. These teams ensure safety and readiness during the critical fueling operations and play a vital role in protecting personnel and hardware throughout the countdown.
2:41 p.m.
NASA teams have transitioned all cryogenic tanks on the SLS (Space Launch System) rocket to replenish mode. This includes both liquid hydrogen and liquid oxygen tanks for the core stage and the interim cryogenic propulsion stage.
Cryogenic propellants naturally warm and evaporate over time, even in insulated tanks. Replenish counteracts this by continuously adding small amounts of liquid hydrogen and liquid oxygen to maintain proper levels and pressure. This ensures the rocket remains fully fueled and stable as the countdown progresses toward terminal count.
Following all stages replenish, teams will perform final system checks and verify valve and sensor performance before transitioning to the terminal countdown sequence, which includes simulated launch operations and final readiness verifications.
With all stages in replenish, the Artemis II wet dress rehearsal is now in its final fueling configuration, bringing this test wet dress rehearsal operations closer to terminal count.
1:50 p.m.
NASA teams have completed the fast fill of the upper stage liquid hydrogen tank on the SLS rocket. Liquid oxygen fast fill continues on the upper stage. On the rocket’s core stage, both the liquid oxygen and liquid hydrogen tanks are in replenish mode. Replenish keeps the tank at flight-ready levels by replacing any liquid hydrogen lost to boil-off.
1:23 p.m.
NASA teams transitioned to fast fill of the interim cryogenic propulsion stage liquid oxygen tank. After completing chilldown, this phase rapidly loads super-cold liquid oxygen, chilled to minus 297 degrees Fahrenheit, into the upper stage tank.
Fast fill is a critical step that ensures the stage is fully fueled and ready to pair with liquid hydrogen for the RL10 engine burn. This engine will provide the in-space boost needed to send Orion into high Earth orbit before its lunar flyby. During this process, teams closely monitor tank levels, pressure, and valve performance to maintain system integrity.
1:07 p.m.
NASA teams have transitioned the SLS rocket’s core stage liquid hydrogen tank to replenish mode. This marks an important milestone in the test, as teams reached this step without exceeding the ground safety limit of the hydrogen leak concentration, as was observed during the first Artemis II wet dress rehearsal.
After completing fast fill and topping, replenish keeps the tank at flight-ready levels by replacing any LH2 lost to boil-off. Replenish is essential for maintaining stable pressure and temperature in the tank as the countdown continues. Cryogenic propellants like liquid hydrogen naturally warm and evaporate over time, even in insulated tanks. Replenishing the tanks counteracts this by continuously adding small amounts of liquid propellant to maintain the correct volume and pressure. This phase ensures the core stage remains fully fueled and ready to power its four RS-25 engines at liftoff, providing the thrust needed to send Orion and its crew on their journey around the Moon.
12:43 p.m.
NASA teams have begun chilldown for the liquid oxygen lines on the interim cryogenic propulsion stage. This critical step cools the hardware ahead of loading super-cold liquid oxygen, chilled to minus 297 degrees Fahrenheit, into the SLS (Space Launch System) rocket’s upper stage tank.
Once complete, teams will transition to slow fill and then fast fill of liquid oxygen, pairing with liquid hydrogen to power the RL10 engine that will send Orion into high Earth orbit before its lunar flyby.
12:30 p.m.
As teams continue to fuel the SLS rocket’s core stage with liquid oxygen and liquid hydrogen, teams began loading liquid hydrogen into the rocket’s interim cryogenic propulsion stage or upper stage.
The core stage liquid hydrogen and liquid oxygen tanks, meanwhile, are currently in fast fill.
12:12 p.m.
Teams began chilling down the liquid hydrogen lines for the interim cryogenic propulsion stage of NASA’s SLS rocket. This critical step cools the propellant lines ahead of loading super-cold liquid hydrogen, chilled to minus 423 degrees Fahrenheit, into the SLS’s upper stage tank.
The chilldown process ensures the hardware is properly conditioned for cryogenic temperatures, reducing thermal shock and safeguarding system integrity. Once complete, teams will transition to fast fill of liquid hydrogen, followed by liquid oxygen operations later in the countdown.
The interim cryogenic propulsion stage, powered by an RL10 engine, will provide the in-space boost needed to send the Orion spacecraft into high Earth orbit before its lunar flyby.
11:45 a.m.
Normal communications have been restored, and NASA teams have made the decision to transition to fast fill of the SLS rocket’s core stage with super-cold liquid hydrogen. Core stage liquid oxygen remains in fast fill.
Fast fill rapidly loads hundreds of thousands of gallons of liquid hydrogen and liquid oxygen into their core stage tanks. During this process, teams also monitor for leaks and conduct engine bleed procedures to thermally condition the RS-25 engines for launch. Once fast fill is complete, operations will move to topping and replenish phases.
Up next, teams will start chilling down the liquid hydrogen tank on the interim cryogenic propulsion stage – or the upper stage – of SLS.
11:11 a.m.
Teams in the firing room at NASA’s Kennedy Space Center are experiencing an issue with ground communications and have moved to backup communication methods to maintain safe audio command and control. The launch director has decided to maintain the current vehicle state, continuing the liquid oxygen fast fill, but delaying moving into liquid hydrogen fast fill, while engineers troubleshoot the issue.
10:43 a. m.
Teams have transitioned from slow fill to fast fill for liquid oxygen on the core stage of the SLS rocket. Liquid hydrogen remains in slow fill for the core stage.
10:30 a.m.
Following successful chilldown of the liquid hydrogen and liquid oxygen lines, teams have started slowly filling the SLS rocket’s core stage with super-cold liquid hydrogen, chilled to minus 423 degrees Fahrenheit, then with liquid oxygen chilled to minus 297 degrees. This marks the official start of propellant loading for the Artemis II wet dress rehearsal.
Slow fill is a deliberate process that allows the tanks and associated hardware to thermally condition before transitioning to fast fill. This step minimizes thermal stress and ensures the integrity of the system as hundreds of thousands of gallons of cryogenic propellant flow into the core stage.
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.
February 19, 2026 7:00AM
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