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As Artemis II — NASA’s mission that will send four astronauts to circumnavigate the moon as soon as next year — draws closer, a new study is revealing how well its Orion spacecraft will protect the crew.
The findings are based off 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 trajectory similar to the one Artemis II is set to take, was uncrewed but carried special nonhuman guests.
Two of them, mannequin torsos called Helga and Zohar, rode along as test of how much radiation astronauts might experience as they venture to the moon. The mannequins were made of materials that mimic the soft tissue, organs and bones of a person and, like the spacecraft, included 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 mitigating radiation experienced on the trip.
“The Artemis I mission marks a crucial step in advancing our understanding of how space radiation impacts the safety of future crewed missions to the Moon,” said Sergi Vaquer Araujo, lead for the space medicine team at the European Space Agency, in a statement.
Araujo was not involved in the study. But the European Space Agency contributed five mobile dosimeters to measure radiation throughout the Orion spacecraft.
“We are gaining valuable insights into how space radiation interacts with the spacecraft’s shielding, the types of radiation that penetrate to reach the human body, and which areas inside Orion offer the most protection,” Araujo said.
Radiation worries
NASA has studied the impact of space radiation on human health for decades, dating back to the first crewed space missions of the 1960s. Data is also regularly collected from astronauts spending six months to a year aboard the International Space Station.
The station remains in low-Earth orbit, meaning it is partly protected by Earth’s magnetic field, as well as heavy shielding incorporated into the orbiting laboratory’s design. Earth’s magnetic field also prevents cosmic rays from reaching the astronauts.
But for future missions to deep space, astronauts will stray far from Earth’s protection and will need to rely on a well-shielded spacecraft and protective spacesuits.
Long-duration space missions to the moon and Mars will expose astronauts to radiation from cosmic rays, or high energy particles that move through space. To reach outer space, astronauts will also have to travel through Earth’s Van Allen Belts, two bands of radiation that surround our planet like giant doughnuts, according to NASA.
Sensors embedded in the Orion capsule captured continuous radiation data on the journey from Earth to the moon and back for the first time, the researchers said. While there is some data from the Apollo missions, it was not collected continuously.
The sensors showed that radiation exposure within Orion varied significantly depending on the location of the detectors, according to the study authors.
A cosmic ‘storm shelter’
As Orion passed through the Van Allen Belts, the data showed the most shielded areas, such as the capsule’s “storm shelter,” provided four times more protection than the least shielded areas. The researchers determined radiation exposure in these spots stayed at a safe level for the astronauts to avoid acute radiation sickness.
“The storm shelter is a very tight area used for storing crew supplies,” said lead study author Stuart George, scientist within the Space Radiation Analysis Group at NASA’s Johnson Space Center in Houston, in an email. “We found that the storm shelter was the most shielded area on the vehicle, which is good because it was designed that way!”
Passing through the Van Allen Belts was considered comparable to the crew encountering a space weather event.
As the sun nears solar maximum — the peak in 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 release from the sun’s outer atmosphere.
When these outbursts are directed at Earth, they can affect spacecraft, satellites, the space station and even the electric power grid on the ground.
“This helped us to validate our shelter design to protect crew from energetic solar particle events caused by space weather,” George said.
Cosmic ray exposures, which can account for the majority of radiation astronauts might experience on long-term spaceflights, were 60% lower on Artemis I than those experienced by previous missions, including robotic missions to Mars, George said.
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 right trajectory. During the flip, radiation levels inside the capsule dropped by 50% because the maneuver placed more of Orion’s shielding within the path of radiation, George said.
The measurements taken during Artemis I could inform the design of future human spaceflight missions, the study authors said.
Planning for Artemis II
If a solar storm were to occur while the Artemis astronauts were in space, it could last for days.
The storm shelter concept has been changed for Artemis II since the smaller shelter aboard Artemis I might not be big enough for the crew to carry out normal operations if they had to remain there for an extended period during a solar storm, also known as a solar particle event.
“On Artemis II, the crew will (bungee) tie 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 will be able to use much more of the cabin while still being effectively sheltered from radiation. It will be really interesting to test this out in space, with crew in the loop.”
The core stage for Artemis II’s powerful rocket arrived at NASA’s Kennedy Space Center in Florida over the summer, and assembly is already underway for the Artemis III rocket. Artemis III — slated for 2026 — aims to land a woman and a person of color at the lunar south pole for the first time.
Meanwhile, the Artemis II crew, including NASA astronauts Reid Wiseman, Victor Glover, Christina Koch and Canadian Space Agency astronaut Jeremy Hansen, have been field training in Iceland. Although they won’t make a landing, the crew will travel 4,600 miles (7,402 kilometers) beyond the far side of the moon to capture images of lunar surface features like craters from orbit.
“Having humans hold the camera during a lunar pass and describe what they’re seeing in language that scientists can understand is a boon for science,” said Kelsey Young, lunar science lead for Artemis II and science officer at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, in a statement.
“In large part, that’s what we’re training astronauts to do when we take them to these Moon-like environments on Earth.”
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