"Due the variability between events, the radiation dose accumulated due to solar protons may vary from negligible to well above lethal. The occurence of solar flares is basically not predictible and, thus, the warning period is only a few minutes to hours at best. The large fluxes associated with major solar flare events are potentially lethal to humans in space or on the surfaces of planets, moons, or asteroids."

- NASA, http://pet.jsc.nasa.gov/alssee/demo_dir/se_radia_fs.html

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