When it launches atop Space Launch System on Exploration Mission 1, NASA's Orion spacecraft will travel far beyond the International Space Station (iss) and beyond the radiation protection offered by Earth’s atmosphere and magnetic field and into the Van Allen Belts, clouds of heavy radiation that surround Earth. No spacecraft built for humans has ventured through the Van Allen Belts since the Apollo missions, and those missions passed right through. While future crewed missions don’t plan to spend more time than necessary inside the Van Allen Belts, long missions to deep space will expose them to more radiation than astronauts have ever dealt with before. During Orion’s first test flight, EFT-1, the spacecraft lingered in the Van Allen Belts. EFT-1’s extended stay in the radiation environment offered a unique opportunity to see how Orion’s shielding held up to it. Sensors recorded the peak radiation seen during the flight, as well as radiation levels throughout the flight, which can b...