Mission designers have tried to protect space systems from the effects of radiation since the discovery of the Earth's radiation belts by the first U.S. satellite, Explorer 1, in 1958. Designers use models based on measurements returned by a host of missions, and Aerospace has been instrumental in developing these models. The first model developed for electrons in the inner radiation belt, AE1, was published in 1965. The figure above on the left shows contours of constant particle flux for relativistic electrons having energies greater than 0.5 MeV as a function of position within the Earth's magnetic field. Similarly, the figure above on the right shows contours of fluxes of protons having energies greater than 1 MeV as described by the current-generation proton model, AP8. This model, along with the corresponding model for electrons, AE8, are today's industry-standard models. Aerospace, along with the Air Force Research Laboratory, has begun an effort to modernize these radiation models using new data and new understanding to provide more accurate and useful models, which will be named AE9 and AP9. The figures immediately to the right show the empirically derived principal components on which AE9 will be based.
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