NASA on Thursday gave the Artemis II astronauts orbiting Earth the go-ahead to head toward the Moon, marking the first crewed lunar flyby in more than 50 years.

Flight Director Jeff Radigan told the crew the mission team had approved firing Orion’s engine to send the spacecraft onto a lunar trajectory. The 5-minute, 49-second burn was scheduled for 7:49 p.m. Eastern (2349 GMT), beginning a three-day journey — the first of its kind since 1972.

“Flight controllers will closely monitor engine performance, guidance, and navigation data throughout the maneuver to ensure Orion remains precisely aligned for the outbound journey,” NASA said.

The Space Launch System rocket carrying Orion lifted off Wednesday from Kennedy Space Center in Florida, launching four astronauts — Americans Reid Wiseman, Victor Glover and Christina Koch, and Canadian Jeremy Hansen.

The crew spent their first hours in space conducting checks and troubleshooting minor issues, including a communications glitch and a toilet malfunction. Before resting, they performed an engine burn to enter high Earth orbit.

“Artemis II astronauts are doing great,” NASA chief Jared Isaacman said. “The Orion spacecraft is performing well in an impressive elliptical orbit.”

NASA said the communications issue was resolved and the astronauts were “in great spirits.”

The 10-day mission will loop around the Moon to pave the way for a planned lunar landing in 2028. It marks several firsts, including the first woman, first person of color and first non-American on a lunar mission. If successful, the crew will travel farther from Earth than any humans before.

The mission is also the first crewed flight of NASA’s Space Launch System rocket, designed to enable sustained lunar exploration.

The Artemis program, delayed by years of setbacks and cost overruns, is seen as part of a broader push to return humans to the Moon amid growing competition with China, which aims for a crewed landing by 2030.