Updated: Jun 6, 2022
Around 5:45pm ET, NASA's Space Launch System (SLS) began moving out of the VAB on top of the Crawler Transporter and Mobile Launch Platform (MLP). That first movement started its roughly 10-11 hour journey to Launch Complex 39B (LC-39B) at 4:15am ET. This is one of the first major steps SLS has to take before launching around the Moon later this summer. A couple weeks from now, SLS will begin what is known as a "Wet Dress Rehearsal", or WDR, where they will run the rocket and systems through a countdown simulating launch day. This involves fueling the rocket and retracting the Crew Access Arm (CAA), then counting down to T-10 seconds, which would be right before RS-25 ignition. After the WDR is completed and considered a success after reviewing the data, the rocket will get picked back up by the Crawler Transporter and brought back into the VAB for final closeouts and preparations for its maiden launch. After a successful WDR is when NASA will determine a launch date, which is currently set for NET June.
The maiden launch of SLS, Artemis I, is a giant step toward bringing humans back to the Moon. This mission will prove the launch vehicle as a whole and pave the way for a better understanding on how to continue to send crew to the Moon and return them back home safely. The next SLS launch vehicle for Artemis II is coming close to completion and the one for Artemis III is under construction.
Below is a gallery of SLS rolling out for the first time taken by Ryan Bale (@rbalephoto on Twitter)