Characteristic γ- and X-radiation in the planetary system

Conclusions Passive observation of the naturally occurring γ-ray and X-ray from the planets is potentially an important technique for determining their gross chemical composition and on the basis of natural γ-radiation determining if the planetary surface is composed of differential material. If the planet is not covered by a thick atmosphere then it is possible to map the distribution of the most abundant elements on a scale of spatial resolution that is of the order of the altitude at which the observations are made. Initial observations carried out from lunar orbit have shown that the flux levels are approximately as expected and that the lunar surface is not characterized by any widespread distribution of acidic rocks in the region observed by the Luna 10 spacecraft.     

Magnetospheric cosmic-ray cutoffs and their variations

Many observations of geomagnetic cutoff phenomena and their implications with respect to the dynamics of charged particles in the geomagnetic field are discussed. Störmer's analytic treatment of the motion of charged particles in a dipole field is briefly reviewed, as are the approximate treatments of charged particle motions, first developed by Alfvén, which were to find successful application to the more complex fields now known to exist in the magnetosphere. In conclusion, the present understanding of geomagnetic cutoffs, together with some remaining areas of uncertainty are examined.