For the first time in more than 50 years, astronauts are heading to the moon. The Artemis II crew launched Wednesday atop NASA's SLS rocket, which left thick trails of vapor across a clear-blue Florida sky. The four astronauts and their team on the ground are now busy preparing for the challenges that lie ahead.
NASA astronauts Reid Wiseman, Victor Glover and Christina Koch, along with Canadian Space Agency astronaut Jeremy Hansen, launched from Kennedy Space Center in Florida, ensconced in an Orion capsule attached to an SLS rocket. The historic mission — the first time in more than half a century that humans have visited the moon — will take them on a 230,000-mile journey around the lunar body and back that will serve as a critical test flight of the Orion spacecraft.
The nearly 10-day mission will not only test the spacecraft's life-support systems and maneuverability, but conduct critical science ahead of future deep space missions to the lunar surface.
The trajectory
The mission is on a flight path that keeps the spacecraft in Earth's gravitational influence past the moon, then falls back to the planet for splashdown. This path, called a free return trajectory, uses less fuel and is less risky than entering a lunar orbit.
About a day after launch, the spacecraft is set to perform a translunar injection, firing its engine and sending the Artemis II crew on their lunar journey.
The path will take the crew to within about 5,000 miles above the lunar surface. Apollo missions typically orbited the moon under 100 miles (or touched down on the surface).
"When they pass by the far side of the moon, it'll look like a basketball held at arm's length," said Artemis II mission scientist Barbara Cohen. "It'll be that kind of view."
Testing, testing
After separating from the rocket that got them into space, but before heading to the moon, the crew tested the Orion spacecraft closer to home.
Just hours after entering high-Earth orbit, the crew performed what's known as a proximity operations test — taking manual control of the vehicle to see how it handles in space.
"We are essentially going to make sure that the vehicle flies the way that we think it does, that we designed it to do," Artemis II pilot Victor Glover said ahead of the launch.
Controlling the spacecraft will be important for future missions, which will need to dock with a lunar lander in orbit. And while this process is likely going to be automated, NASA wants to know how it handles should astronauts have to take manual control.
"We also want to give qualitative and quantitative feedback to the ground team, so letting them know what it feels like now that we can hear and feel the thrusters, and to just understand the human experience," said Glover.
Near the end of the maneuver, the pilot appeared to give the vehicle high marks.
"Overall guys, this flies very nicely," he told team members on the ground.
Time for science
The astronauts themselves will be the subject of science experiments: Because the crew is going farther into deep space than any human has gone before, researchers are taking this opportunity to study the impact it will have on the human body.
Medical researchers will be collecting data on physiological changes in response to space travel and increased radiation exposure. The astronauts' cells have been placed on tiny chips and distributed throughout the capsule — in an effort to understand these effects in greater detail.
The crew will also lend their eyes for geological research, since they are flying around the far side of the moon, where no human has ventured before.
"They'll be able to see places on the moon that, actually, no human eyes have ever seen before," said Cohen.
Geologists on Earth trained the crew to spot unique features on the lunar surface, and snap photos of them for further study. (This follows in a time-honored tradition: Apollo astronauts who visited the moon more than a half century ago were also trained by geologists.) These observations will help them better understand that side of the moon, and possibly help plan for a human landing.
And the mission's high-altitude flyby of the moon gives them a unique perspective.
"The benefit of that to science, is that kind of like when you're traveling cross country on an airplane, what you can see is a strip of land below you. You don't see the whole globe of the Earth. That's what the Apollo astronauts did," said Cohen. "The Artemis II astronauts will be able to see it from much farther away."
The mission is also carrying stowaways in the form of CubeSats — tiny satellites bound for high-Earth orbit. The payloads are from Germany, South Korea, Saudi Arabia, and Argentina, and will study various impacts of space radiation on space hardware, monitor space weather, and how the environment affects electrical hardware bound for the moon.
Heading home
As the crew makes their return home, their capsule will be traveling close to 25,000 miles per hour as it re-enters the atmosphere. The friction generated by hitting the atmosphere at that speed will cause the Orion capsule to experience temperatures of close to 3,000 degrees Fahrenheit.
The capsule is equipped with a heat shield to protect the astronauts from the intense heat of reentry. During an uncrewed test flight in 2022, NASA discovered unexpected damage to the heat shield. To further protect the crew, the capsule will hit the atmosphere at a much steeper angle than Artemis I, which will limit the time it will experience those harsh conditions.
Once the spacecraft is past that danger zone, eight parachutes will slow the spacecraft down even more before splashing down in the Pacific Ocean off the coast of California. A series of airbags will deploy to make sure the capsule is right side up. A crew at sea will scoop up the astronauts, bringing their mission to a close.
What's learned on this flight is critical to future Artemis missions. Last week, NASA administrator Jared Isaacman announced plans to increase the frequency of launches to the moon, and a plan to establish a permanent base on the lunar surface. That effort begins with Artemis II.
"It is our strong hope," said Artemis II mission specialist Christina Koch, "that this mission is the start of an era where everyone, every person on Earth, can look at the moon and think of it as also a destination."
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