Artemis II Launch Director Charlie Blackwell-Thompson has given the "go" for ground teams to begin fueling the SLS rocket, a procedure known as tanking.

Fueling begins with the chilldown step, a critical process that cools the rocket's plumbing and engine systems to super-cold cryogenic temperatures so there aren't any issues when ground teams begin to load the fuel of cryogenic liquid hydrogen and liquid oxygen.

-ABC News' Matthew Glasser

NASA is broadcasting a live feed of the Artemis II moon rocket from the Kennedy Space Center on Merritt Island, Florida.

Teams are activating the ground launch sequencer, the computer that will initiate terminal count -- the final, automated 10 minutes of launch countdown -- which will tell the rocket when to lift off.

Engineers are also initiating the air‑to‑gaseous nitrogen changeover inside the rocket's cavities. NASA says atmospheric air is replaced with inert nitrogen gas, which creates a stable environment before fueling operations.

Watch the live feed here.

The Artemis II moon mission will see four astronauts go on a 685,000-mile, 10-day journey around the moon. Here is what the timeline looks like:

Day 1 is launch day. The astronauts lift off aboard NASA's newest spacecraft, Orion, which will sit atop the Space Launch System rocket. The spacecraft will reach initial orbit and then high-Earth orbit to make a push toward the moon.

Days 2 through 4 are transit days, with the journey to the moon taking three days. Over the course of the journey, the crew will continue to evaluate Orion's systems and practice emergency procedures, in addition to other activities.

On day 5, Orion will enter the lunar sphere of influence, meaning the moon is the main gravitational pull. On day 6, the crew will come its closest to the moon while traveling the farthest from Earth, according NASA.

Days 7 through 10 will see the astronauts make their way back to Earth before re-entering Earth’s atmosphere at high speed, up to 25,000 miles per hour.

The Orion spacecraft will deploy a series of parachutes once through the heat of re-entry to slow down and it will splash down in the Pacific Ocean The U.S. Navy will recover the capsule.

-ABC News’ Mary Kekatos

#Who are the Artemis astronauts?

Three Americans and one Canadian will be aboard the Orion spacecraft -- named "Integrity" -- over the course of 10 days.

The team consists of Victor Glover, Christina Hammock Koch and Reid Wiseman of NASA and Jeremy Hansen of the Canadian Space Agency.

Wiseman is the commander of the Artemis II mission, Glover is the mission pilot, and Koch and Hansen are mission specialists.

Glover and Koch will also be the first person of color and first woman, respectively, to eventually step foot on the lunar surface in future Artemis missions.

-ABC News' Julia Jacobo