H3: Radiation Environment in Heliosphere: SEPs and GCRs


 Jingnan Guo


Robert Wimmer-Schweingruber


  • Human Exploration 
  • (Aero)Space Assets Functions


S3 Cluster: Sophie Murray

Human Exploration: Eddie Semones, NASA/JSC Space Radiation Analysis Group, edward.j.semones@nasa.gov


Solar Energetic Particles (SEPs) and Galactic Cosmic Rays (GCRs) are electrically charged particles with energies which significantly exceed those of typical solar-wind particles (typically 0.5 - 4 keV/nuc). As such they are bound to the interplanetary or heliospheric magnetic field (IMF) by the Lorentz force. Their gyro-radii depend on their energy and the strength of the magnetic field. Because of their large speed relative to that of the solar wind and their large gyro-radii, the local properties of the SEPs and GCRs are not determined by the local properties of the IMF, but at much larger scales. Thus, understanding and predicting the flux of SEPs and GCRs in the heliosphere requires knowledge of the IMF throughout the heliosphere and at the Sun.


To understand, characterize and predict the flux of SEPs. To achieve these objectives three crucial issues need to be understood: 

  • the injection of particles into the acceleration process, 
  • the acceleration process itself, 
  • the transport of SEPs (and GCRs) to the location for which predictions are to be made. 

Essential Space Environment Quantities / Forecasting Problems:  

Action topics:

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