Space weather can be deadly. Here’s how NASA protects the Artemis II crew.

In October 1989, a blast from the sun flung out a stream of super-powered protons. This solar storm lasted for days and forced astronauts working in low-Earth orbit, aboard NASA’s Atlantis space shuttle, to retreat to a shielded storm shelter in the farthest interior of the craft.

Even while hunkered down, some of the crew reported seeing flashes of light as high-energy particles struck their retinas. It remains one of the biggest solar proton floods ever observed. A NASA researcher later estimated that, if the astronauts had been outside of our planet’s protective magnetic field instead of in low orbit, they would have had a 10 percent chance of dying during the solar storm.

Such storms and other hazardous radiation threats fall under a broader umbrella called space weather. Over the last week, NASA’s Artemis II crew has ventured far beyond the safety of our planet’s magnetic field, where solar storms pose even more serious threats. Even as the threat of space weather remains. But researchers have learned some tricks about how to handle these dangers since the 1989 storm.

The Artemis II crew’s vessel, Orion, is the first vehicle designed explicitly to deal with risks like high-energy proton flurries. The uncrewed Artemis I mission, which flew around the moon in 2022, carried sensors that measured radiation levels all over the craft, providing potentially life-saving information during its sojourn through space. Orion was designed with both a dedicated storm shelter and special shielding to absorb radiation, and sensors onboard the spacecraft are measuring radiation levels throughout the mission.

“We gained a lot of confidence in our models and systems,” says Stuart George, a physicist at NASA’s Johnson Space Center in Houston who helps to measure and mitigate space weather effects. “It's a really good vehicle from a radiation point of view.”

What are the dangers from space weather? 

The Orion spacecraft is facing three types of space radiation as it travels from the earth to the moon and back. Such radiation acts as subatomic shrapnel, shredding human tissue and DNA and leaving behind ions that can cause molecular chaos inside the body.

Even before they left the part of space dominated by Earth’s magnetic field, the Artemis II crew passed through the Van Allen Belts, two donut-shaped regions extending between 600 to 60,000 kilometers above the planet (that’s higher than the International Space Station flies). These belts are filled with fast-moving protons and electrons trapped by the Earth’s magnetic field. While such particles can be as harmful as those encountered during a big solar storm, Orion zipped through the belts in less than an hour, limiting the crew’s exposure.

The second hazard comes from galactic cosmic rays—atomic nuclei, protons, and electrons jetting through space at significant fractions of light speed. Thought to be expelled by distant exploding stars, cosmic rays are especially dangerous because shielding against them only makes things worse. As these ultra-fast thermonuclear bullets slam into the body of a spacecraft, they cause tiny explosions and unleash a cascade of additional energetic particles, each of which can damage human tissue.

(How do cosmic rays affect us on Earth?)

The only way to mitigate against such radiation is to travel during periods of high solar activity, since the stream of charged particles surging off the sun creates a protective bubble, much as the Earth’s magnetic field shields against solar threats. Artemis II is flying a short time after the most recent peak in the sun’s 11-year cycle in late 2024.

But this also introduces the final form of space radiation, energetic particle events, flares, and mass ejections from the sun. These become far more likely during solar maximum. Yet because of the danger from unstoppable galactic cosmic rays, it’s still safer to travel at such periods than when the sun is quieter.

How do we detect solar storms?

NASA and the National Oceanic and Atmospheric Administration (NOAA) operate several satellites that monitor the sun, looking out for large events like the powerful flare that blasted out just before Artemis II launched. One of the main workhorses is the Deep Space Climate Observatory (DSCOVR), situated about 1.6 million kilometers sunward. DSCOVR records solar activity and provides between 15 and 60 minutes of advanced warning before a particle storm hits the Earth. 

And in September 2025, the agencies launched three new satellites to monitor different types of solar activity—the Interstellar Mapping and Acceleration Probe (IMAP), Carruthers Geocorona Observatory, and SOLAR-1. Each reached their final position near DSCOVR in January, and SOLAR-1 in particular is poised to provide 24/7 observations of flares and eruptions. Data from all these observatories is fed into sophisticated forecasting software that tries to determine when inclement space weather is imminent.

Researchers focus on active regions of the sun, areas full of complex magnetic twists that tend to contain sunspots and are prone to launching streams of particles. “It's very similar to a paper airplane with a rubber band,” says Patricia Reiff, a space physicist at Rice University in Texas. “The more you wind that rubber band, the more kinks you have [and] the more energy you put in.” Let go of the band and it will violently unravel, launching the paper airplane. Likewise, the kinks in the sun’s magnetic field lines get so twisted that they can bend no further, forcefully snapping apart and propelling charged particles and radiation into space. 

Much like extreme weather events here on earth, such outbursts happen randomly. Scientists might be able to infer when energy is building up in active regions on the sun based on sunspots and other data, raising the probability that a storm could be unleashed. But there’s no way to perfectly predict when a burst will occur.

(Future lunar explorers might take shelter in the moon’s caves.)

What do astronauts do in case of a space weather event? 

Last year, officials from NASA, NOAA, and space industry experts gathered in Boulder, Colorado to simulate how to forecast space weather using the latest models and respond to a potential emergency during Artemis II. Participants monitored fake events based on past data, relayed vital information to one another, and figured out what guidance to give astronauts beyond Earth’s magnetic field.  The event was “eye-opening” and extremely useful, says Shawn Dahl, a forecaster at NOAA’s Space Weather Prediction Center in Colorado. If a solar storm were to happen during a deep space mission, these early warning systems would be critical.

Thanks to advanced satellite warning, officials have at least a short window for figuring out how a storm’s danger level. If forecasts suggest the astronauts may be in peril, they will be ordered to move to Orion’s storm shelter. This is a tiny area at the base of the spacecraft where each astronaut has essentially a small locker that they can stuff themselves into. They will place additional padding and material over their heads to hunker down.

Yet a solar tempest can last many days, and the mission designers didn’t want to trap the Artemis II astronauts in a cramped space forever. So, the spacecraft’s walls contain aluminum and high-density polyethylene to absorb some radiation. The crew can also build a special emergency shelter using storage and waste bags—basically anything they can get their hands on and place against the interior walls of the ship. “A colleague described it as ‘an innovative use of available materials,’” says George. (The DIY shelter has also been likened to “a pillow fort.”) 

As more humans journey to the moon and perhaps one day Mars, efforts to predict and react to space weather will be vital—and Artemis II’s data and tech are just the first step.