 discuss solar proton event man space flight discuss solar proton event man space flight result studi intern geophys year igi intern geophys cooper igc consider fraction larg solar flare rise pure stream proton reach earth continu arriv long 11 dai energi particl lie steep spectrum extend 20 500 mev frequenc larg flare time high solar activ long durat solar proton emiss particl detect intens top earth's atmospher 15 percent time 1957 1960 number larg flare acceler releas particl three-year period 30 event began august 22 1958 contribut greatli understand solar terrestri sequenc event addit provid identif emit particl flare proton neighborhood earth phenomenon recogn addit radiat hazard man vehicl high atmospher part solar system three intens event occur juli 1959 support conclus possibl predict event consider addit protect human be effect forecast clearli great detail scientif studi phenomenon paper present preliminari discuss aspect predict arriv proton earth appear solar activ featur equal forecast period penetr radiat occur 