Evaluation of Radiation Interference in the Voyager Sun Sensor´s Cadmium Sulfide Detector

The simulation of radiation interference effects and the results of a radiation interference test on two Voyager Sun Sensor prototype detector assemblies are reported. The derivation of test levels and requirements are discussed and show that cobalt 60 gamma radiation is an effective and practical simulator of the ionization dose rate effects induced by high-energy electron flux incident on the spacecraft at a rate of 3.7 × 108 e/cm2 s (10 rad(Si)/s) during closest approach to Jupiter. The test results provide information that is used to confirm an analytic correlation, and to predict satisfactory performance of a spacecraft Sun sensing device having stringent angular resolution requirements. The measured detector response shows that at dose rates incident on the detector elements of 2 rad(Si)/s, which is four times that expected during Jupiter encounter, the radiation-induced angle error is almost an order of magnitude less than that allowed by the acceptance criteria.