NASA to roll out 11 million-pound moon rocket in preparation for astronauts' launch

NASA will roll a 322-foot-tall rocket out to the launchpad on Saturday, a key step as the agency prepares for a long-awaited mission to send four astronauts around the moon.

The Space Launch System rocket, topped with the Orion capsule, which will carry the astronauts, is set to make the slow, 4-mile journey from NASA’s cavernous Vehicle Assembly Building — where the rocket’s various components were put together — to the launchpad at Florida’s Kennedy Space Center, beginning at 7 a.m. ET. NASA will stream the event, known as “rollout,” live on its YouTube channel.

The event will kick off a series of tests and dress rehearsals that, if successful, will take the agency into final preparations for its first crewed flight to the moon in more than 50 years. The mission, known as Artemis II, could lift off sometime between Feb. 6 and 11, though launch windows are also available in March and April.

The rollout is a key step for mission managers to assess the health and safety of the booster before NASA leaders finally set an official launch date.

“These are the kind of days we live for,” John Honeycutt, the Artemis II mission management team chair, said Friday in a news briefing.

The Artemis II mission plan calls for four crew members — NASA astronauts Reid Wiseman, Victor Glover and Christina Koch, and Canadian astronaut Jeremy Hansen — to spend 10 days in space, journeying first around Earth then entering orbit around the moon.

The rollout on Saturday could last up to 12 hours. An enormous, moving platform known as a crawler-transporter will carry the 11 million-pound Artemis II rocket to NASA’s historic Launch Pad 39B, which was also used during the Apollo and space shuttle programs.

The stacked transporter will inch along at a careful snail’s pace of about 1 mile per hour, according to NASA.

Once the rocket arrives at the launchpad, crews will begin preparations for an upcoming launch-day walkthrough, known as the wet dress rehearsal. During this event, NASA fuels the rocket and runs through all the standard procedures that would take place on the day of liftoff, right up until the T-minus 29 second mark in the countdown, according to Artemis launch director Charlie Blackwell-Thompson.

“Launch day will be pretty similar to wet dress,” she said. “There’ll be two big differences: One is that we’re going to send the crew to the pad, and the other one is we’re not going to stop at 29 seconds.”

The wet dress rehearsal will allow mission managers to evaluate how the rocket’s systems work together in real-world environments and will give engineers the opportunity to check for fuel leaks or other technical issues.

If any problems crop up, the rocket will need to be rolled back to the Vehicle Assembly Building for additional work. But if all goes smoothly, NASA may soon announce its targeted launch date.

The Artemis II flight will be the most rigorous test yet for the Space Launch System rocket and Orion spacecraft — the first time the system will be carrying a crew.

While flying inside the Orion capsule, the astronauts are expected to conduct tests of the spacecraft’s docking capabilities and life-support systems while in orbit both around Earth and the moon.

A successful mission will set the stage for the Artemis III flight, scheduled for sometime in 2027, which will land astronauts near the moon’s south pole.

Returning to the moon has been a priority for President Donald Trump, particularly as a new space race intensifies between the U.S. and China. Chinese officials have said they intend to land their own astronauts on the moon by 2030.

This article was originally published on NBCNews.com