A radiation model for geocentric trajectory calculations

A solar cell degradation model developed for the SECKSPOT trajectory optimization code is presented. The model is based on two analytic expressions, one describing solar cell power degradation as a function of 1 MeV equivalent fluence and cell base resistivity and thickness, and one describing a spatial field of 1 MeV equivalent electron flux. The model extends the latitude range, provides a continuous and smooth representation of the flux field, and provides for changing the cell characteristics. Construction of a 1 MeV electron flux model and of a power loss model are described. It is shown that modeling the 1 MeV flux field as a separate entity allows simple consideration of both front and back shielding, and that the coefficients relating to specific cell damage data can be simply updated using the latest cell damage data once the general analytical characteristics of the model have been established.