  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.
