NASA's Artemis II mission lifted off on Wednesday from Florida, sending four astronauts on the first crewed flight around the moon in more than 50 years.

The Space Launch System rocket, with the Orion spacecraft atop, launched from NASA's Kennedy Space Center at 6:35 pm Eastern Time.

The four astronauts have started an approximately 10-day journey around the moon. The crew consists of NASA astronauts Reid Wiseman, Victor Glover and Christina Koch, along with Canadian Space Agency astronaut Jeremy Hansen.

Together, they will travel approximately 7,400 kilometers beyond the far side of the moon before returning to Earth.

According to NASA's update, the mission's early stages proceeded largely as planned. At 6:43 pm, the Space Launch System core stage shut down its main engines and separated from the interim cryogenic propulsion stage and Orion spacecraft. By 6:59 pm, all four of Orion's solar array wings had fully deployed and begun generating power. Upcoming milestones include a perigee-raise maneuver and an apogee-raise burn to prepare the spacecraft for deep-space operations.

About 51 minutes into the flight, however, Orion experienced a communications disruption during a planned handover between satellites, causing a temporary partial loss of contact, said NASA Administrator Jared Isaacman at a postlaunch news briefing. The agency was working to determine the cause of the problem.

The Artemis II mission aims to demonstrate a broad range of capabilities required for deep space exploration, including validating Orion's life-support systems and allowing astronauts to practice operations critical to future lunar missions.

The mission had been delayed multiple times due to technical setbacks. In early February, hydrogen fuel leaks during a countdown dress rehearsal forced a repeat test of the Space Launch System rocket. Following that repeat test later in the month, a separate issue emerged involving an interruption in the flow of helium to the rocket's upper stage, which is critical for purging the engines and pressurizing the fuel tanks.

Artemis II is NASA's first crewed mission under its Artemis lunar exploration program, which was announced in 2019 with the original goal of landing astronauts on the moon by 2024. The agency conducted Artemis I, an uncrewed moon-orbiting mission, in November 2022.

NASA revised its Artemis program timeline in February, inserting an additional mission and postponing the crewed lunar landing from 2027 to 2028. Under the updated plan, Artemis III will focus on testing systems and operational capabilities in low Earth orbit in 2027, ahead of the Artemis IV lunar landing mission in 2028.