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As Artemis II, NASA’s mission that will send four astronauts around the moon next year, approaches, a new study reveals how well the Orion spacecraft will protect its crew.
The findings are based on data from Artemis I, a 25-day journey around the moon and back in late 2022. The Orion capsule on that mission, which followed a similar trajectory to Artemis II, was unmanned but carried special non-human guests.
Two of them, mannequin torsos named Helga and Zohar, were included as a test of how much radiation astronauts might experience when they go to the moon. The mannequins were made of materials that mimic human soft tissue, organs and bones and, like the spacecraft, contained detectors to track radiation exposure along the way.
Now, scientists have released the first results after studying the detector data, published Wednesday in the journal Nature. The findings show that the shielding technology used in the spacecraft was effective in reducing the radiation experienced during the journey.
“The Artemis I mission marks a crucial step in increasing our understanding of how space radiation affects the safety of future manned missions to the Moon,” said Sergi Vaquer Araujo, head of the space medicine team at the European Space Agency, in a statement.
Araujo was not involved in the study. But the European Space Agency provided five mobile dosimeters to measure radiation inside the Orion spacecraft.
“We are gaining valuable insights into how space radiation interacts with the spacecraft’s shielding, which types of radiation penetrate to reach the human body, and which areas of Orion offer the most protection,” Araujo said.
Concerns about radiation
NASA has been studying the impact of space radiation on human health for decades, dating back to the first manned space missions in the 1960s. Data is also regularly collected from astronauts who spend six months to a year aboard the International Space Station.
The station remains in low Earth orbit, which means it is partially protected by Earth’s magnetic field, and by heavy shielding incorporated into the design of the orbital laboratory. Earth’s magnetic field also prevents cosmic rays from reaching the astronauts.
But for future missions into deep space, astronauts will be far from the protection of Earth and will have to rely on well-shielded spacecraft and protective spacesuits.
Long-duration space missions to the moon and Mars expose astronauts to radiation from cosmic rays, or high-energy particles that travel through space. To reach space, astronauts must also travel through Earth’s Van Allen radiation belts, two bands of radiation that encircle our planet like giant doughnuts, according to NASA.
Sensors built into the Orion capsule have for the first time recorded continuous radiation data during the journey from Earth to the moon and back, the researchers said. While there is some data from the Apollo missions, it was not collected continuously.
According to the study authors, the sensors showed that radiation exposure in Orion varied significantly depending on the location of the detectors.
A cosmic ‘storm shelter’
As Orion passed through the Van Allen Belts, data showed that the most shielded areas, such as the capsule’s “storm shelter,” provided four times more protection than the least shielded areas. Researchers determined that radiation exposure in these areas remained at safe levels for the astronauts to avoid acute radiation sickness.
“The shelter is a very tight space used to store crew supplies,” Stuart George, lead author of the study and a scientist in the Space Radiation Analysis Group at NASA’s Johnson Space Center in Houston, said in an email. “We found that the shelter was the most shielded area on the vehicle, which is good because it was designed that way!”
A journey through the Van Allen belts has been likened to a space weather event.
As the sun approaches solar maximum — the peak of its 11-year cycle, expected this year — it becomes more active, releasing intense solar flares and coronal mass ejections. Coronal mass ejections are large clouds of ionized gas called plasma and magnetic fields that are released from the sun’s outer atmosphere.
When these bursts are aimed at Earth, they can affect spacecraft, satellites, the space station, and even the electrical grid on the ground.
“This helped us validate our design for a shelter to protect the crew from energetic solar particles caused by space weather,” said George.
According to George, exposure to cosmic rays, which can account for the majority of the radiation astronauts experience during long-duration spaceflight, was 60 percent lower on Artemis I than on previous missions, including robotic missions to Mars.
The team also noted a surprise in the findings. As Orion passed through the Van Allen Belts, the spacecraft did a flip to perform a thruster burn, ensuring it was on the correct trajectory. During the flip, radiation levels inside the capsule dropped by 50 percent because the maneuver placed more of Orion’s shielding in the path of the radiation, George said.
According to the study authors, the measurements taken during Artemis I could be important for the design of future space missions.
Plans for Artemis II
If a solar storm were to develop while the Artemis astronauts are in space, it could last for days.
The storm shelter concept has been modified for Artemis II because the smaller shelter aboard Artemis I may not be large enough for the crew to conduct normal operations if they have to remain there for an extended period of time during a solar storm (also known as a solar particle explosion).
“On Artemis II, the crew will use a bungee tie to secure supplies to the least shielded wall of the Orion spacecraft,” George said by email.
“This means that during an energetic solar particle event, the crew can use much more of the cabin while still being effectively shielded from radiation. It will be very interesting to test this in space, with the crew in the loop.”
The core stage for the powerful Artemis II rocket arrived at NASA’s Kennedy Space Center in Florida this past summer, and assembly has already begun on the Artemis III rocket. Artemis III — scheduled for launch in 2026 — aims to land the first woman and person of color on the moon’s south pole.
Meanwhile, the Artemis II crew, including NASA astronauts Reid Wiseman, Victor Glover, Christina Koch and Canadian Space Agency astronaut Jeremy Hansen, has been conducting field training in Iceland. Though they won’t be landing, the crew will travel 4,600 miles (7,402 kilometers) beyond the far side of the moon to take images of lunar surface features like craters from orbit.
“It’s a boon to science that people are holding the camera during a flyby of the moon and describing what they see in language that scientists can understand,” Kelsey Young, chief of lunar science for Artemis II and a scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, said in a statement.
“That’s largely what we train astronauts for when we take them to these lunar-like environments on Earth.”
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