Radiation-Induced Backgrounds in Astronomical Instruments: Considerations for Geo-synchronous Orbit and Implications for the Design of the WFIRST Wide-Field Instrument

Geo-Synchronous orbits are appealing for Solar or astrophysical observatories because they permit continuous data downlink at high rates. The radiation environment in these orbits presents unique challenges, however. This paper describes both the characteristics of the radiation environment in Geo-Synchronous orbit and the mechanisms by which this radiation generates backgrounds in photon detectors. Shielding considerations are described, and a preliminary shielding design for the proposed Wide-Field InfraRed Survey Telescope observatory is presented as a reference for future space telescope concept studies that consider a Geo-Synchronous orbit.