The **wet dress rehearsal** officially commenced on Tuesday evening and extended into Wednesday, with the team powering up both the rocket and spacecraft components while charging flight batteries. The crucial part of this test began on Thursday morning when mission managers approved the fueling of the **Space Launch System (SLS) rocket**.
At around **10:30 a.m. ET**, liquid hydrogen and liquid oxygen were initiated into the rocket’s core stage. The booster housed over **700,000 gallons of cryogenic propellant**, and mission managers executed a countdown leading up to a simulated launch time of **8:42 p.m. ET**.
The **refueling test** appeared to proceed smoothly, with NASA performing two walkthroughs during the last 10 minutes of the countdown. A pause occurred at approximately **T minus 1 minute and 30 seconds**, followed by a reset of the countdown clock to **T minus 10 minutes** near **T minus 33 seconds** for the final moments before liftoff.
These pauses were meticulously designed to demonstrate that the rocket’s systems were functioning as anticipated during critical countdown phases, when automated systems assume control of the booster. Additionally, these moments allowed mission managers to rehearse various scenarios, including resolving issues that necessitate investigation or aborting a launch due to technical difficulties or adverse weather conditions.
During the crucial refueling process, initiated at 12:30 PM ET on Monday, mission managers temporarily halted operations twice to investigate a hydrogen fuel leak emanating from the rear of the rocket.
Although testing of the Orion spacecraft atop the rocket resumed, the hydrogen leak reoccurred in the final moments of the mock launch countdown.
NASA reported that a built-in control system on the rocket, designed to manage the booster in the countdown’s critical final minutes, “automatically halted the countdown due to a sudden spike in liquid hydrogen leakage.”
Engineers are also looking into audio issues that affected communication channels for ground teams during the wet dress rehearsals.
The four astronauts set to embark on Artemis II — NASA’s Reed Wiseman, Christina Koch, Victor Glover, and Canadian astronaut Jeremy Hansen — were expected to arrive at Kennedy Space Center on Tuesday afternoon after being quarantined in Houston since January 21 to minimize exposure to bacteria before their mission.
However, NASA has confirmed that the astronauts will not proceed to Florida as anticipated and will be released from their quarantine.
Instead, they will undergo quarantine again approximately two weeks before the next targeted launch opportunity, according to agency officials.
Artemis II marks the second flight for NASA’s Space Launch System rocket and Orion capsule, and it will be the first mission with humans on board.
This much-anticipated launch is set to advance NASA’s objectives of returning astronauts to the lunar surface.
The previous unmanned Artemis I lunar orbit mission in 2022 faced a six-month delay due to a hydrogen leak detected during the initial wet dress rehearsal.
The Artemis II flight carries significant importance, being the inaugural crewed mission aboard the Space Launch System rocket and Orion capsule.
“Our highest priority remains the safety of our astronauts, personnel, systems, and the public,” Isaacman stated on X, emphasizing that NASA will “proceed with the launch only when we are confident in our readiness for this historic mission.”
As NASA gears up for the highly anticipated Artemis II mission, the space agency is preparing for a crucial test that will determine the readiness of its powerful Moon rocket, the Space Launch System (SLS).
This essential “wet dress rehearsal” simulates a full launch day, allowing engineers to fill the SLS rocket with fuel and perform all launch operations up to 30 seconds before liftoff, mimicking real mission conditions.
The results of this rehearsal will be instrumental for engineers and mission managers to evaluate the booster’s performance and overall readiness for the Artemis II mission.
Set to launch by Sunday, Artemis II will embark on a groundbreaking 10-day mission, taking four astronauts farther from Earth than any humans have ventured before.
However, the actual launch date will heavily rely on the outcomes from the wet dress rehearsal.
NASA Administrator Jared Isaacman will hold a press conference with the Artemis II crew on January 17th at Kennedy Space Center. Joe Radle/Getty Images
“We’ll take some time to review the data and prepare for launch,” stated Artemis launch director Charlie Blackwell Thompson during last month’s press conference.
If the rehearsal proceeds without issues, NASA could announce a targeted launch date in a matter of days. Conversely, any problems could lead to mission delays.
Engineers and mission managers will execute a countdown to the mock launch scheduled for 9 PM ET on Monday. Over 700,000 gallons of cryogenic propellant will be loaded into the SLS in the hours leading up to the test, with NASA planning to livestream this crucial process. For more information, check out the Artemis Rocket 24/7 Live Stream at the launch pad.
As part of the rehearsal, mission managers will simulate the countdown several times during the final 10 minutes, which will provide essential data on the rocket’s systems, including an automated control that engages 30 seconds prior to launch.
Artemis II marks NASA’s second mission using the Space Launch System rocket and Orion capsule, with this being the inaugural crewed flight—a pivotal step toward NASA’s goal of returning astronauts to the lunar surface.
The Artemis II crew consists of NASA astronauts Reed Wiseman, Christina Koch, Victor Glover, and Canadian astronaut Jeremy Hansen, who have been in isolation at NASA’s Johnson Space Center in Houston to ensure they remain healthy prior to the mission.
On January 17, NASA successfully positioned the Space Launch System rocket carrying the Orion capsule at Kennedy Space Center in Florida. The agency initially planned a wet dress rehearsal for Saturday but rescheduled due to unexpected cold weather across the Southeast and mid-Atlantic.
NASA’s Artemis II at Kennedy Space Center on January 17th. Joe Radle/Getty Images
Due to the scheduling changes, NASA has eliminated the first two launch windows (Friday and Saturday) for this month, which ends on February 11th. If additional launch opportunities arise, slots may also be opened in March and April.
Ensuring a successful wet dress rehearsal is crucial for a smooth launch this month.
Should issues arise during testing, NASA may need to return the rocket to the vehicle assembly building, reminiscent of the six-month delay faced by Artemis I’s unmanned lunar orbit flight after a hydrogen leak was detected during its initial wet dress rehearsal.
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