NASA's Artemis I Moon rocket and spacecraft depart Launch Pad 39B

On Saturday, NASA's Artemis I Moon rocket, the Space Launch System, and Orion spacecraft left Launch Pad 39B and began their 4-mile trek to the Vehicle Assembly Building (VAB) at the agency's Kennedy Space Center in Florida.

The 4-mile trek atop the crawler-transporter from the launch pad to the VAB started at approximately 4:12 a.m. ET and will take approximately 8-12 hours.

The mission teams completed the wet dress rehearsal test campaign for Artemis I on June 20 and have configured the rocket and spacecraft for return to the VAB. Once there, teams will replace a seal on the quick disconnect of the tail service mast umbilical to address a liquid hydrogen leak detected during the wet dress rehearsal, along with planned forward work as the Space Launch System and Orion spacecraft are readied for launch, the agency said.

For the unversed, Artemis I is the first in a series of increasingly complex missions that will pave the way toward landing humans on the Moon and Mars. The mission will be an uncrewed flight test of the SLS rocket and Orion around the Moon, during which the spacecraft will venture thousands of miles beyond the moon over the course of about a four to six-week mission.

Touted as the most powerful rocket ever built by NASA, SLS is the only rocket that can send Orion, astronauts, and supplies to the Moon in a single mission.

At 4:12 a.m. ET the @NASAArtemis Moon rocket began making its four-mile trek back to the Vehicle Assembly Building from Launch Pad 39B.Tune in to watch @NASA_SLS and @NASA_Orion arrive to the iconic assembly building later this morning: https://t.co/ufyDGCtbJ4 pic.twitter.com/MR1O3YxpWT

— NASA's Kennedy Space Center (@NASAKennedy) July 2, 2022

NASA, through the Artemis program, plans to land the first woman and the first person of color on the Moon and use the learning to take the next giant leap: sending the first astronauts to Mars.