Total mission dose is the sum of three sources that move independently across the ~11-year solar cycle:
- Trapped belts — fixed by orbit geometry alone. LEO mostly stays below them, MEO cuts straight through, GEO grazes the outer edge, interplanetary transits never see them.
- Galactic cosmic rays (GCR) — a near-constant background that gets weaker at solar maximum, because a more active solar magnetic field deflects more of it. Counterintuitively, GCR dose is highest at solar minimum.
- Solar particle events (SPE) — sudden storm spikes from flares/CMEs, rare near solar minimum and frequent (and larger) near solar maximum.
Move the solar-cycle slider and re-run the same orbit/duration to see the three bands trade weight with each other rather than one factor simply dominating.