With the help of their closeout crew, the Artemis II astronauts have entered the Orion crew module, which they named "Integrity."

This mission will be the first time humans travel into space on Orion.

Artemis II will be a crucial step in testing the systems on the spacecraft for future deep space missions back to the moon.

-ABC News' Briana Alvarado

The Artemis II crew has arrived at the launchpad at the Kennedy Space Center in Florida. 

NASA has said the four astronauts remain on track to launch at 6:24 p.m. ET.

The four-person Artemis II crew is heading to Launch Complex 39B at the Kennedy Space Center in Florida.

"It's a great day for us. It's a great day for the team," mission commander Reid Wiseman told a crowd of family members, fans and media after exiting the Operations and Checkout Facility.

The astronauts piled into an Astrovan to transport them across campus to the launch tower.

-ABC News' Briana Alvarado and Mary Kekatos

Imagine being cramped in the back seat of a car for several hours as the twists and turns of the highway intensify already uncomfortable circumstances.

Now imagine similar conditions on a 10-day trip, traveling a distance of 685,000 miles at over 20,000 miles per hour.

That's what lies ahead for the four astronauts on the Artemis II mission onboard the Orion crew module.

Read more here.

-ABC News' Mason Leib

A second-grader's plush toy design has rocketed to space alongside astronauts Reid Wiseman, Victor Glover Jr., Christina Koch and Jeremy Hansen on board the Artemis II moon mission.

Lucas Ye, 8, designed a white moon plush named "Rise," which wears an Earth cap with a brim highlighting the galaxy and rockets.

Lucas and his family were invited to witness the Wednesday evening launch of Artemis II at the Kennedy Space Center, an experience that Lucas described to "Good Morning America" on Thursday as "really cool."

"I feel very lucky. A little idea can turn out into a big thing," Lucas told "GMA."

Read more here.

-ABC News' Yi-Jin Yu and Nic Uff