Countdown begins for Artemis II wet dress rehearsal at Kennedy Space Center

The countdown for the Artemis II wet dress rehearsal is underway at NASA’s Kennedy Space Center in Florida. The countdown clock began at 8:13 p.m. EST, or L-48 hours, 40 minutes before the opening of a simulated launch window at 9 pm. Mon, Feb. 2. The test is expected to go until approximately 1 a.m.

Feb. 3. The rehearsal will run the launch team and supporting teams in the Mission Control Center at NASA’s Johnson Space Center in Houston and other NASA centers through a full range of operations, including loading cryogenic liquid propellant into the SLS rocket’s tanks, conducting a launch countdown, demonstrating the ability to recycle the countdown clock, and draining the tanks to practice scrub procedures.

NASA is providing a 24/7 live stream of the rocket at the pad, a separate feed during tanking activities, and real-time blog updates during fueling day. The countdown uses “L minus” and “T minus” times. "L minus" indicates how far away they are from liftoff in hours and minutes, while "T minus" is a sequence of events built into the countdown.

Pauses or "holds" are built into the countdown to target a precise launch window and provide time for tasks; during planned holds the T- time stops while the L- time continues to advance.

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