The cosmic ray track record of events in early solar system

ABSTRACT The character of cosmic ray nuclear track record in extraterrestrial samples is discussed particularly with a view to see how the ‘record’ is affected by change of ‘geometry’ of irradiation. This forms the basis for extracting information from the observed record about the physical evolution of the sample on the one hand, and about variations in the cosmic ray beam composition and energy spectrum on the other. The richness of the record of accumulation processes in the early solar system owes itself to combination of a particularly favorable number mass distribution of cratering objects extending over many decades, and to the depth sensitive production rate of cosmic ray tracks. Information available to date about early solar system processes is summarised. Potential new areas of study accessible to the nuclear track method are outlined.