Electronic sun incidence avoidance device

Abstract

One-dimensional sun sensing and angle measurement assemblies are deployed with substantially totally overlapping fields of view on a plane of a spacecraft body to protect sensors within a protected angular area of the plane, each of the analog sun sensors generating a signal indicative of incident sun along one axis and the presence of sunlight along an orthogonal axis thereto in the common plane. The sensors together generate an indication of the orientation of the sun relative to a target field of view which is a protected area. In an alternative embodiment, a digital sun sensor assembly is provided consisting of two or more independent digital channels and employing a slit aperture cooperating with a plurality of photocells laid out in a gray coded pattern. The digital device produces digital signals indicating relative position relative to axes in a plane. Such signals can be used during a spacecraft operation to override any other control logic in order to stop satellite motion that may bring the field of view of the protected instrument into an undesired orientation relative to the sun.