Reinterpretation of the reported energetic particle fluxes in the vicinity of Mercury

During the Mercury flyby of Mariner 10, observations of large fluxes of energetic electrons (E less than 0.3 MeV) and protons (0.53 greater than E greater than 1.9 MeV) have been reported by Simpson et al. (1974a). The reported simultaneous enhancements of protons and electrons in the magnetic field of Mercury have raised some perplexing planetology questions. It is shown here that the response of the proton detector in the Mariner 10 experiment is most plausibly attributable to the pileup of low-energy electrons rather than the presence of protons in the vicinity of Mercury. Further, the reported lower-limit electron differential spectrum exponent of γ less than or equal to 9 and the 300-keV electron fluxes are probably in quantitative error, especially where the count rates are highest. It is concluded that no ''new'' acceleration mechanism has been identified at Mercury