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Freefall in color by many folks.

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Florence: We have two other sources of radiation. Cosmic rays and solar energetic particles. These are mostly high speed protons and helium. They do direct damage and can produce secondary radiation.
Florence: They're best shielded by light materials. Hydrogen is good.
Florence: Oh. On this trip, every now and then, you're going to see a bright flash of light. That's a cosmic ray interacting with your eye or a visual neuron.
Sam: Light flashes. Got it. An unfriendly reminder from the universe that it's messing with my brain.