Design for High Accuracy Critical-Angle Sun Transit Sensor
MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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A sun transit sensor is used to detect the suns passing a meridianal coordinate plane of the satellite. Accuracy of operation of earlier sensors is limited by curvature of the fan beams associated with the critical angle prism. A new, two-element critical angle prism assembly was described having the following properties a curvature of the fan beam can be cancelled, or balanced against higher order terms, b reflection occurs at the interface between the glasses, c achromatism is possible. A sensor utilizing two such prism assemblies operating in push-pull exhibits a planar fan beam having accuracy of or - sun latitude range of or - 30 deg equatorial orbit requirement, or or - 5 arc seconds for sun latitudes of 5 deg ecliptic orbit requirement. Equations governing the design, the choice of radiation resistant glasses, fabrication and testing will be discussed.
- Spacecraft Trajectories and Reentry