The Simulation of Space Radiation Damage to Spacecraft Systems

Space radiation has induced damage to spacecraft in near earth orbits in a number of documented cases. Explorer XIV, Explorer XV, UK-1, TRAAC, TRANSIT IV B and TELSTAR I were among these. It has become imperative that an adequate laboratory simulation technique be found and applied to future spacecraft to extend the useful lifetime of spacecraft and prevent premature failures. The choice of the equipment for carrying out laboratory simulations at Goddard Space Flight Center has been made by an analysis of damage produced in semiconductor devices. The relative damage produced in semiconductors with various particle energies was compared with the number of those particles at each energy in space to produce a curve showing the particle energies which are most damaging in space. From the curves it becomes clear that energies from about 1 to 4 Mev are the most damaging for electrons and protons. Therefore, the Goddard Space Flight Center will have a facility with a 0.5-3 Mev electron accelerator, a 0.5-4 Mev proton accelerator and a 0.1-1 Mev proton-electron accelerator, to cover the low energy range. The facility will also have a 30,000 curie Cobalt 60 area able to irradiate whole spacecraft to simulate ionization damage effects. With these facilities a reasonable program of radiation hardening of long-lived spacecraft may be carried out.