Space weather could threaten NASA’s Artemis II astronauts during their trip to the moon | Scientific American

March 31, 2026

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How NASA will keep the Artemis II astronauts safe from space weather

A major solar storm during the Artemis II mission could harm astronauts. Here’s how NASA is protecting them

By Meghan Bartels edited by Lee Billings

An artist's depiction of the sun unleashing a coronal mass ejection (CME) in the direction of Earth, which is shown surrounded by its magnetosphere.

NASA MSFC

The hazards that the Artemis II crew must navigate during their 10-day flight are plentiful, starting from the second they launch aboard the most powerful rocket to ever carry humans and continuing all the way through their return to Earth nestled inside the Orion capsule.

Many threats the crew will face are obvious, but not all of them are. Take, for example, radiation, which with moderate exposures can increase an astronaut’s long-term risk of cancer and with heavy doses can cause acute sickness. The Artemis II crew will be the first humans in decades to travel beyond low-Earth orbit, fully discarding the protection of Earth’s magnetic field. And while most aspects of cosmic radiation are straightforward to plan for, the outlier is space weather.

So far, Artemis II’s space weather forecast looks clear. “Right now, we’re not keeping an eye on anything,” Lori Glaze, NASA’s acting associate administrator for exploration systems development, told reporters during a press briefing held on March 29, three days before the mission’s next launch attempt. But NASA is loath to simply hope for the best when astronauts’ health is at stake.

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And rightfully so—just hours after Glaze’s remark, the sun unleashed an X-class solar flare, the most powerful type known. Such flares are dangerous not only because of their radiation but also because of their tendency to precede coronal mass ejections (CMEs)—immense stellar outbursts of electronics-frying, cell-damaging clouds of charged plasma particles. This flare was no exception, being followed by a fast-moving CME. The CME is expected to at least graze Earth, triggering a moderate geomagnetic storm watch on March 31, with a minor watch continuing into the coming days. NASA does not anticipate any effects on the Artemis II mission, currently targeting launch on April 1 at 6:24 P.M. EDT, but the event is a timely reminder of why radiation monitoring and space weather awareness are key aspects of the flight.

Breaking Down Radiation

Artemis II’s journey will expose the crew members—NASA astronauts Reid Wiseman, Victor Glover and Christina Koch and Canadian Space Agency astronaut Jeremy Hansen—to three different kinds of radiation: the galactic cosmic rays that ricochet through all of space, the protons and electrons magnetically trapped in the two Van Allen Belts that ring Earth and the so-called solar energetic particles that emanate from our sun.

But unlike the easily predictable radiation exposures from flying through the Van Allen Belts or basking in the background flux of galactic cosmic rays, the dose an astronaut gets from solar activity can vary enormously. Predicting space weather remains a decidedly inexact science, comparable to weather forecasting decades ago on Earth. Risks are higher during periods of greater solar activity, which follows an 11-year cycle that researchers track by tallying the dark sunspots that represent magnetic storms capable of producing outbursts.

Right now, the sun is finally moving out of several years of solar maximum—but as this week’s outbursts show, our star is not yet quiet. “Things are still active. It’s kind of a roller-coaster ride at this point,” Shawn Dahl, a forecaster at the National Oceanic and Atmospheric Administration’s (NOAA) Space Weather Prediction Center who is part of a team consulting with NASA on radiation risks, told Scientific American in early March. “We don’t know what to anticipate when Artemis finally goes up.”

All Eyes on the Sun

Not all space weather is a threat—plenty of activity streams off the sun away from Earth’s neighborhood, for example. And the material also matters; what’s of most risk to astronauts is showers of high-energy protons and ions that can tear through metal and flesh alike, damaging DNA and other delicate cellular machinery. Typically, these showers are linked to CMEs, which can push material ahead of them at high speeds. But even CMEs are not automatically a danger: plenty of this material never gains enough energy to threaten astronauts.

“The types of events that we’re concerned about are in the to