The Trip to the Far Side of the Moon | WIRED

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When NASA’s new moon rocket lifts off as soon as April 1, its immense core stage will mix 537,000 gallons of liquid hydrogen with 196,000 gallons of liquid oxygen and ignite the propellant in four, eight-foot-wide engines, producing some 1.7 million pounds of thrust. Shortly after these main engines fire, two solid rocket boosters, one on each side, will light their gunpowder-like propellant to add 3.3 million pounds of thrust each.

This immense force will lift the 322-foot-tall rocket, named the Space Launch System (SLS), on the first leg of Artemis II, a more than 600,000-mile journey to the moon and back.

“It’s like a whole building lifting up into the air,” says Nathalie Quintero, SLS core stage operations lead at Boeing, which built the central part of the rocket. “Just the sizing of it is huge.”

The SLS rocket for Artemis II, a 10-day lunar flyby mission, recently rolled out of the Vehicle Assembly Building (VAB) and was positioned on the launch pad at NASA’s Kennedy Space Center. NASA initially rolled the rocket to the pad in January, but the agency had to bring it back to the VAB to address an issue loading helium onto the upper stage. The mission’s next window to launch is between April 1 and April 6.

Artemis II comes more than three years after Artemis I, the first and only uncrewed test flight of SLS and the Orion spacecraft. That first flight carried two mannequins named Helga and Zohar to measure radiation doses, but this second flight will carry flesh-and-blood astronauts, the first people to make the journey to the moon since Apollo 17 in December 1972.

The four-person crew includes commander Reid Wiseman, a Navy pilot who has lived aboard the International Space Station and taken two spacewalks; pilot Victor Glover, also a naval aviator who has lived and worked on the ISS; mission specialist Christina Koch, a field scientist and space instrument engineer who holds the women’s record for longest single spaceflight at 328 days; and mission specialist Jeremy Hansen, a Royal Canadian Air Force pilot who will serve as the first Canadian to ever venture to the moon.

These four will join 24 others as the only people in history to fly all the way to the moon, an average distance of about 240,000 miles. When Artemis II launches, the moon will be near its farthest point, closer to 250,000 miles away. And because the Artemis II astronauts will fly at a higher altitude above the lunar surface than the Apollo astronauts did, they will travel farther from Earth than anyone has before.

“We will very likely, depending on the launch period that we launch in, see things that no human has ever seen,” Wiseman said during a press conference leading up to launch.

NASA plans to follow Artemis II with Artemis III in mid-2027. That mission will test a lunar lander from SpaceX, Blue Origin, or both in low-Earth orbit, practicing rendezvous and docking maneuvers. Artemis IV, which NASA hopes to launch in 2028, would then land astronauts on the lunar surface. The long-term goal of the Artemis program is to continue with a series of missions to establish a crewed lunar station in preparation for missions to Mars and beyond.

The Orion spacecraft for NASA’s Artemis II (right), Artemis III (left), and Artemis IV (center) missions stationed next to each other inside the high bay of the Neil Armstrong Operations and Checkout Building at NASA’s Kennedy Space Center in Florida on June 22, 2023.

Courtesy of: NASA/Marie Reed

Before NASA can facilitate a grand interplanetary expansion, it needs to do something that hasn’t been done in more than 53 years: successfully fly astronauts to the moon and back. The journey is unique in its extreme distance, a quarter million miles from Earth. The farthest crewed spaceflight that was not to the moon was Polaris Dawn, a private flight on a SpaceX Dragon that carried current NASA administrator Jared Isaacson and three other people 875 miles from Earth. The ISS orbits at about 250 miles.

“Deep space travel is inherently risky,” says Paul Anderson, the deputy program manager for the Orion spacecraft at Lockheed Martin. “[In] low-Earth orbit, you’re a couple hours away from getting home. From the moon, you’re four days from getting home at best.”

The lunar trip will start with the explosive launch of the SLS rocket, which will become the most powerful vehicle that people have ever flown on and only the second rocket to send people to the moon.

“As the rocket is going up, it's going through a trajectory and makes the adjustments based on what the receiving inputs are in flight,” Boeing’s Quintero says. “All that has to come together in harmony, kind of like an orchestra.”

About two minutes after launch, the solid rocket boosters that provide most of the liftoff thrust will be ejected. Some six minutes later, the main engines will cut off, and the core stage will separate and fall away. In t