SOLAR ENERGETIC PARTICLE (SEP) EVENTS ARE AN IMPORTANT ASPECT OF SOLAR-TERRESTRIAL PHYSICS AND A MAJOR SPACE WEATHER CONSTITUENT POSING A RECOGNIZED RADIATION HAZARD FOR HUMAN ACTIVITIES IN SPACE INCLUDING FUTURE MISSIONS TO THE MOON AND MARS. WHILE IT IS WIDELY BELIEVED THAT SHOCKS DRIVEN BY CORONAL MASS EJECTIONS (CMES) ARE THE DOMINANT SOURCE OF ACCELERATION FOR LARGE SEP EVENTS THE DETAILS OF HOW SEPS REACH THESE EXTREME ENERGIES (>1 GEV) ARE STILL NOT WELL UNDERSTOOD (E.G. DESAI&GIACALONE 2016). IT S ALSO DEBATED WHETHER EXTREME SEPS ARE ACCELERATED IN FLARES (E.G. KAHLER ET AL. 2017). THE COMPLEX NATURE OF BOTH PARTICLE ACCELERATION AND PROPAGATION POSES CHALLENGES TO DEVELOPING A UNIVERSAL PICTURE OF THESE PROCESSES IN A WIDE ENERGY RANGE FROM THE SUPRATHERMAL TAIL (ST) POPULATION TO THE MOST ENERGETIC SEPS PRODUCING GROUND LEVEL ENHANCEMENTS (GLES) RECORDED BY GROUND-BASED INSTRUMENTS. THE IMPACT ON THE NEAR-EARTH ENVIRONMENT FROM SUCH EXTREME SEP EVENTS IS CONSIDERABLE AFFECTING SPACE-BASED INSTRUMENTATION AIRCRAFT CREWS AND ASTRONAUTS AND IMPARTING CONSIDERABLE ENERGY TO THE EARTH S ATMOSPHERE. SUCH EXTREME EVENTS WERE LIKELY MUCH MORE FREQUENT IN THE PAST AND IMPARTED SUFFICIENT ENERGY TO THE EARLY EARTH TO BREAK APART ATMOSPHERIC N2 MOLECULES CONTRIBUTING TO THE FORMATION OF GREENHOUSE GASES THE PROGENITORS TO AMINO ACIDS AND THUS THE BUILDING BLOCKS OF LIFE (AIRAPETIAN ET AL. 2016 2019).
$38,898FY2020National Aeronautics and Space AdministrationNASA
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