Four astronauts are preparing to travel farther from Earth than any humans have gone in more than five decades, as NASA’s Artemis II mission marks humanity’s return to the vicinity of the moon for the first time since Apollo 17 touched down in December 1972.

The mission will not land on the lunar surface. The crew will not walk on the moon. What they will do is fly around it, push several thousand miles beyond it, and come straight home. The simplicity of the plan, in some ways, makes it more audacious. NASA is putting human beings back in deep space to prove the hardware works before committing to the complex landing mission that follows.

The four-person crew includes NASA astronauts Reid Wiseman, Victor Glover and Christina Koch, along with Canadian Space Agency astronaut Jeremy Hansen. Wiseman serves as commander. Koch made history during her time aboard the International Space Station and will become the first woman to travel to lunar distance. Glover will be the first Black astronaut to fly on a deep space mission. Hansen will be the first Canadian to leave low Earth orbit.

The spacecraft carrying them is Orion, mounted atop NASA’s Space Launch System rocket, the most powerful rocket the agency has ever built. Artemis I, an uncrewed test flight that flew a similar trajectory in late 2022, validated the basic hardware. Artemis II is the first time NASA puts people inside it.

The trajectory works like this: Orion will launch from Kennedy Space Center and use a trans-lunar injection burn to escape Earth’s orbit. The crew will spend days in transit, swinging around the far side of the moon and then continuing outbound to a point roughly 4,600 miles beyond the lunar surface. There, they will execute a turn and begin the long coast back toward Earth. The entire mission runs approximately 10 days.

The absence of a landing is a deliberate engineering and risk management choice. Before NASA commits crew members to lunar orbit, descent, surface operations and ascent, the agency wants proof that Orion’s life support, propulsion and communication systems function properly with astronauts aboard in the deep space environment. Radiation levels beyond Earth’s magnetosphere are significantly higher than what crews encounter on the International Space Station, and the mission will generate real data on how the spacecraft and its occupants hold up.

Artemis II also gives flight controllers and the crew a chance to practice procedures that will matter enormously on subsequent flights. Artemis III is expected to attempt the first crewed lunar landing since 1972, relying on a commercial lander from SpaceX. That mission would put astronauts, including the first woman and the first person of color, on the lunar surface near the south pole, a region of scientific interest because of suspected water ice deposits in permanently shadowed craters.

The south pole focus reflects broader competition in space. China has announced its own crewed lunar ambitions, targeting a landing before the end of the decade. NASA officials have been direct in framing Artemis as part of an effort to establish a sustained American presence on and around the moon before other nations do.

The mission carries the weight of interrupted ambition. The last time a human being looked back at Earth from the distance Artemis II will reach, Richard Nixon was president and the Vietnam War was still ongoing. An entire generation grew up believing that lunar travel was the beginning of something larger. Then it stopped.

Wiseman, Glover, Koch and Hansen will fly with the accumulated technology of the decades since, but also with the pressure of a program that has faced repeated delays and cost overruns. The Space Launch System has drawn criticism from budget analysts and commercial space advocates who argue the agency leaned too heavily on expensive existing contractors when cheaper alternatives were emerging.

None of that will matter in the cabin once the engines ignite. Four people will be heading to the moon. The question NASA is betting billions to answer is whether the path it built can get them there and back safely, and whether what follows will finally make that a routine journey rather than a rare one.