Cape Canaveral, Florida On Saturday (Jan. 17), the rocket that will carry the Artemis 2 astronauts around the moon moved onto the launch pad for its historic journey, which may begin in just a few weeks.

NASA’s Space Launch System (SLS) rocket, designed to support the agency’s Artemis 2 mission and usher in a new era of crewed flights to the moon, departed from the Vehicle Assembly Building (VAB) at Kennedy Space Center (KSC) in Florida on Saturday, beginning a 4-mile (6.4-kilometer) journey to Launch Complex-39B (LC-39B).

Engineers spent the last year and a half stacking the Artemis 2 SLS, which emerged from the VAB today for the first (and perhaps only) time as a completely built launch vehicle. SLS began its voyage at 7:04 a.m. EST (1204 GMT), standing on the rocket’s Mobile Launch Platform (MLP), whose giant 7.5-foot (2.3 m) treads carried the rocket from the VAB’s High Bay 3 onto the river-rock-covered road leading to the launch site. The rocket reached LC-39B at 6:42 p.m. EST (2342 GMT).

SLS is 322 feet (98 meters) tall and weighs around 2,870 tons (2,600 metric tons) when fully fueled. The rocket is fueled by two space shuttle-era solid rocket boosters (SRBs) that are stacked 177 feet (54 m) tall on either side, as well as four RS-25 engines that were originally designed for the space shuttle. They generate 8.8 million pounds of thrust during liftoff to propel the rocket’s upper stages and Orion crew capsule into orbit.

The enormous vehicle took approximately 12 hours to go from the VAB to LC-39B, moving at less than 1 mph (1.6 kph). Now that it’s on the launch pad, NASA will spend the next few weeks doing system integrations and vehicle checkouts in preparation for a fuelled launch countdown simulation known as a wet dress rehearsal, and, if everything goes well, a launch attempt in early February.

NASA plans to do a wet dress rehearsal on February 2. The earliest probable launch date for Artemis 2 is February 6, when NASA astronauts Reid Wiseman, Victor Glover, and Christina Koch, as well as Canadian Space Agency astronaut Jeremy Hansen, will board the Orion spacecraft for a roughly 10-day voyage around the moon.

The launch date is largely determined by how well systems checks go after SLS arrives at the pad, with backup launch possibilities scheduled until February 11 and additional openings in March and April.

Artemis 2 is NASA’s second Artemis mission and the first to fly a crew aboard Orion. Artemis 1 premiered in November 2022, following a checkout campaign that lasted the majority of the year. After its debut in March 2022, the Artemis 1 SLS wet dress rehearsals and launch attempts were hampered by cryogenic hydrogen leaks, weather delays, and other issues, necessitating three journeys back to the VAB for repairs.

NASA officials are hoping to avoid a similar campaign with Artemis 2, and they are confident in the rocket’s readiness and optimistic about a launch in February.

When it launches, SLS will bring Orion to Earth orbit, where the Artemis 2 crew will undergo system checks before a translunar injection burn that will propel them toward the moon. That burn will be completed by SLS’ interim cryogenic propulsion stage, from which Orion and its service module will separate to execute proximity maneuvering experiments on their journey to lunar space.

The Artemis 2 astronauts will not proceed into lunar orbit. Instead, the mission will use a “free-return trajectory” to circle the capsule around the moon and slingshot it back to Earth, regardless of any abnormalities encountered by the crew or spacecraft during the voyage. The flight path ensures the safe return of the Artemis 2 crew and Orion, eliminating the danger of a malfunction leaving them stranded in lunar orbit.

Artemis 2 is the next step in NASA’s plan to return men to the lunar surface and establish a facility in the moon’s south polar area. Artemis 3 will be the first mission prepared for a lunar landing, but it will only launch if Artemis 2 is successful.

Artemis 2 will be as much a testing ground for Orion’s life support systems as Artemis 1 was for the spacecraft’s overall architecture. Any unanticipated speed bumps on the forthcoming mission could create more delays for Artemis 3, whose expected launch date is already beginning to slide past NASA’s optimistic 2027 target.

Artemis 2 crew members have been training at KSC for months, doing launch-day rehearsals in preparation for their mission, and were present to witness their SLS rocket launch for the first time today.