Radiation Environment Predictions for Laboratory Tests

Abstract : Long-duration space environment exposure tests are performed to examine effects that might occur with materials exposed on external spacecraft surfaces. To properly simulate the orbital environment, information regarding the charged-particle environment is required. Once the orbital environment is known and tabulated, an energy deposition code is used to calculate energy dose depth profiles in selected materials for the electron and proton fluences during the mission. These are then simulated using a series of monoenergetic species that together sum up to a close approximation of the orbital dose profile. The specific information needed for the environment in a particular orbit is the flux of the radiation as a function of energy. This information is generally available from upper-atmosphere models such as AE8 and AP8; however, these models are deficient at lower particle energies, resulting in under-prediction of the surface fluence. In this report, a method to predict a suitable radiation environment for laboratory simulations of a LEO orbit is described.