For the first time in more than 50 years, humans are about to return to the Moon. The Artemis II mission is set to launch on March 6 to bring four astronauts on a loop around the Moon, which will mark the closest point ever reached to our natural satellite since the Apollo 17 astronauts returned to Earth in 1972.
“We’ve been hearing for so long, ‘We’re going back to the Moon,'” says planetary scientist Marie Henderson of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Now this generation of lunar scientists can be part of the action.
NASA originally planned to launch Artemis II as early as February 6. But after a “wet” dress rehearsal on February 2 identified a leak in the rocket’s tank filling system with liquid hydrogen propellant, NASA decided to push back the launch until March to allow time for additional testing and another dress rehearsal.
Artemis II won’t actually land on the moon. This is a task for future Artemis missions, the details of which are still being worked out.
This means that this mission is more analogous to Apollo 8 from 1968, which was the first time humans orbited the moon. Like Apollo 8, Artemis II is primarily a technology demo, aimed at testing the systems needed to keep humans alive in deep space and eventually land them on the moon. Science still plays a role.
“The main objective [for Apollo 8] “While there is science here, the main goal of the program is to test the systems to ensure they are ready for future exploration.”
But science is built into Artemis II in ways that Apollo 8 couldn’t even dream of, from the technology the astronauts can use to the astronauts’ scientific training to the very architecture of the control room. This time, says Henderson, “science and exploration go hand in hand; we cannot do one without the other.”
Artemis II will be the first time humans will fly aboard NASA’s Orion space capsule, which circles the moon with models on board in 2022 as part of Artemis I. The four astronauts — NASA’s Reid Wiseman, Victor Glover and Christina Koch, along with Canadian astronaut Jeremy Hansen — will launch NASA’s Space Launch System rocket. Once in orbit, the Orion capsule will separate from its engines, circle the Earth twice to make sure everything is working as expected, then launch its rockets to push the spacecraft onto a figure-8 lunar trajectory. The entire journey is expected to last 10 days and could travel about 400,000 kilometers from Earth, further than any human has traveled before.
The overall goal of the Artemis program is to lay the foundations for a long-term human presence on the Moon and, ultimately, to prepare for human missions to Mars.
To this end, much of the science carried out on the mission will use astronauts as subjects. Astronauts will wear bracelets to constantly monitor their movements, sleep and stress levels. They will carry radiation sensors in their pockets to collect data on how many potentially harmful high-energy particles they are exposed to when not shielded by Earth’s magnetic field.
Astronauts will collect saliva samples in small stamp books to track changes in immune biomarkers before, during and after the flight. And the flight will carry small chips that look like USB drives containing cells grown from the astronauts’ blood. This “organ-on-a-chip” is meant to mimic astronauts’ bone marrow, which creates the immune cells that keep astronauts healthy in space. Back on Earth, researchers will study how genes in cells changed following spaceflight.
The moon itself is also a mission star. Artemis II could be the first time human eyes will see the dark side of the Moon.
Human eyes have seen photos of the hidden side of the Moonlike those taken by the Lunar Reconnaissance Orbiter, in orbit around the Moon since 2009. The Chinese Chang’e-6 mission brought the first samples back from the hidden side in 2024. Artemis I also took a look at the hidden side.
With all this robotic data, you might think there isn’t much left to add to humans. But human eyes can pick up nuances that cameras can’t, Henderson says. The Artemis crew may notice rapid changes, such as the flash of a meteorite creating a new crater. Astronauts will be able to view the same location from different angles and in different lighting conditions during the flyby, giving a sense of depth and 3D space that would take cameras months to create. And humans have a different sensitivity to color than cameras. Henderson notes that the Apollo 17 astronauts spotted orange ground from orbitwhich helped them choose a landing site. Samples of this soil were later determined to be pieces of volcanic rock that had erupted 3.6 billion years ago.
But unlike Apollo 8, which circled the Moon 10 times before returning to Earth, Artemis II astronauts will only have a few frantic hours to observe the Moon up close on their single loop.
Fortunately, the astronauts themselves received more scientific training than that of Apollo 8. Most early Apollo missions included all fighter pilots. The Apollo 8 crew studied as much lunar geology as possible. But the mission was planned quickly and they had many other things to do.
“Apollo 8 was a very technical and operationally difficult mission with a very tight timetable for science mission planning,” Richard Allenby, director of NASA Manned Space Science, wrote in a 1969 report on the photographs and visual observations of Apollo 8. “The fact that a valid science plan was generated is a tribute to the scientists associated with the mission.”
Later Apollo missions, particularly the last three, included more deliberate scientific planning. “Many scientific goals evolved in the mid-1960s,” says Muir-Harmony. Starting with Apollo 15, “astronauts get some pretty incredible training in geology,” she says. “Much of this important science happened in later Apollo missions, after some of the technical goals had already been achieved.”
Artemis II astronauts are preparing for both technical tests and scientific observations. The crew underwent classroom training, regular “moon homework,” and field expeditions to places on Earth that resemble lunar terrain, such as Iceland and Arizona. The crew and science team also performed several hands-on simulations in which the crew looked out the window of a replacement Orion capsule at a replacement lunar map, which was sometimes a huge inflated moon hanging from a crane.
These exercises are designed to help the crew ensure that their descriptions of the landscape are scientifically useful. They will describe things like color, shape of features, textures, and anything else they notice. In a practical simulation, one of the crew members described a feature as resembling a kiss, Henderson says.
“Our astronauts are scientists themselves,” says Henderson. In addition to their background in geology, Hansen has a master’s degree in physics, and Koch did remote scientific field work in the Arctic and Antarctic before becoming an astronaut. “We view them as an extension of our scientific team,” says Henderson. “I think it will increase scientific output. Instead of little bits here and there that we can extract, we know we’ll have a huge body of scientific data that we can dive into.”
Henderson is deputy lunar science manager for Artemis II, a job that didn’t even exist during Apollo 8. During Orion’s lunar flyby, she will lead a team of geologists and lunar scientists in the new Science Evaluation Room at NASA’s Johnson Space Center in Houston. His team will analyze the data, ask questions and send advice to the crew in real time.
Scientists will communicate with the crew through NASA’s Kelsey Young, who has another new position: science officer. Young will be in the mission control room and speak directly to the astronauts, alongside other support officers who will track things like spacecraft health and communications. His job is to make sure science is one of the factors considered when making decisions about what the astronauts will do and how the spacecraft will move — for example, whether the capsule should rotate to get a better view of the moon from the windows.
Henderson and his team will create a personalized observation plan – an interactive map with annotated lists of things to observe, images of what the astronauts might see, and note-taking points for making drawings and annotations – and upload it to the crew’s tablets after launch.
The science team won’t know what lunar features the crew will be able to see until two days after launch, because the moon will be in a different position relative to the spacecraft depending on when Orion begins its path to the moon from Earth’s orbit. But Henderson isn’t bothered by the uncertainty.
“There are so many different areas I would be excited about,” she says. “I really don’t care when it launches, because I know it’s going to be good.”