However, the simple fact that most satellites have weathered the vagaries of natural space radiation so well over time indicates their normal design hardening is better than assumed. Military satellites in LEO are much more hardened, whereas the hardness of commercial platforms may vary. It is noteworthy that natural background radiation does vary significantly over time and yet not many satellites are known to have failed due to this variability. For example, under natural background radiation conditions in LEO, the peak flux for electrons with energy greater than 1 MeV ranges from 10^4 for the outer radiation belt to 10^6 for the inner. Enhanced solar flux is said to have resulted in >1 MeV electron flux to reach 10^8 particles/sq cm sec. Coincidentally, this is the same magnitude that is computed by the model due to a high-altitude nuclear explosion one day after the burst over Korea.

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Lewis, Leo and Phillip E. Coyle. Ensuring America's Space Security. Washington, D.C.: Federation of American Scientists, September 2004. [ 7 quotes ] [ page 26-7 ]