ACS WFC CCD Radiation Test: The Radiation Environment

The space environment is a complex, orbit dependent phenomenon. Regardless of orbit, the external surfaces of a spacecraft will be exposed to photons, charged particles and solid particles such as micrometeoroids. Vehicles in low earth orbit (LEO) must be designed to withstand additional environmental hazards such as hyper-velocity impacts by man-made orbital debris and erosion of external surfaces by naturally occurring atomic oxygen. CCD detectors are particularly vulnerable to damage by ionizing radiation. This document summarizes the modeling and analysis that was performed to determine the appropriate exposure level for ground testing of the Advanced Camera for Surveys (ACS) Wide Field Channel (WFC) Charge-Coupled Device (CCD) detector.