The Risks of Deep-Space Travel

The Artemis II mission, a 10-day flight beyond low-Earth orbit, presents unique challenges for its crew: NASA astronauts Reid Wiseman, Victor Glover, and Christina Koch, along with Canadian Space Agency astronaut Jeremy Hansen. Unlike missions in low-Earth orbit, these travelers will move beyond the protection of Earth's magnetosphere, exposing them to three primary types of radiation: galactic cosmic rays, protons and electrons in the Van Allen Belts, and solar energetic particles.

Understanding Solar Threats

While radiation from the Van Allen Belts is predictable, solar activity remains highly variable. Solar flares and coronal mass ejections (CMEs)—massive outbursts of charged plasma—pose the greatest risk to human health. These events can damage DNA and cellular machinery, though solar physicist Ricky Egeland notes that the most dangerous events are exceedingly rare, occurring in only the top 5 to 10 percent of observed space weather.

Enhanced Protection and Monitoring

NASA has significantly improved its ability to mitigate these risks compared to the Apollo era. The Orion capsule features advanced shielding, and the crew is trained to create a "shelter" within the spacecraft by moving bulky items to line the walls if a solar alert is issued. Furthermore, NASA now utilizes a sophisticated network of sun-monitoring spacecraft, including NOAA’s new Space Weather Observations at L1 and data from the Perseverance rover on Mars, to provide real-time situational awareness.

Lessons from Artemis I

The 2022 Artemis I mission provided critical data to validate these safety measures. By outfitting the uncrewed Orion capsule with over 5,600 radiation sensors, NASA confirmed that its predictive models accurately reflect the radiation environment inside the vehicle. This data gives the agency high confidence in its current approach to protecting the Artemis II crew as they prepare for their historic journey.