NASA is preparing to begin a new era of space exploration with the launch of Artemis II, the first crewed mission toward the Moon since the end of the Apollo program 53 years ago. Barring any last-minute delays, the massive Space Launch System rocket is scheduled to lift off Wednesday evening from Kennedy Space Center in Florida, during a two-hour launch window that opens at 6:24 p.m. EDT.

The mission will carry four astronauts: Reid Wiseman, Victor Glover, Christina Koch and Jeremy Hansen. The crew aboard the Orion spacecraft will fly thousands of miles beyond the Moon, loop around it and return to Earth in less than 10 days, without entering lunar orbit or landing on the surface.

The flight will mark several historic milestones. Koch will become the first woman to travel beyond Earth orbit toward the Moon; Glover will become the first Black astronaut to take part in a lunar mission; and Hansen will become the first Canadian to venture into deep space.

The spacecraft is expected to travel more than 252,000 miles from Earth, surpassing even the record set by Apollo 13. During the journey, the astronauts will test Orion’s life-support, communications and maneuvering systems with a human crew for the first time, a critical step before Artemis III, NASA’s planned lunar landing mission in 2027.

The 322-foot SLS rocket was rolled to Launch Pad 39B at Kennedy Space Center just days ago after an 11-hour trip from the Vehicle Assembly Building. NASA says there are no outstanding technical concerns and weather conditions remain favorable, although there is still roughly a 20% chance of delay due to weather or solar activity.

NASA has until April 6 to launch Artemis II before standing down until the end of the month, because the Earth and Moon must align precisely for the mission’s trajectory. If the launch does not occur this week, the next available window opens on April 30.

Artemis II is part of NASA’s broader plan to establish a long-term human presence on the Moon during the next decade and eventually use it as a stepping stone for future missions to Mars. NASA hopes to return astronauts to the Moon’s south pole in 2027 and build a permanent lunar base before 2030.