Popis: |
This paper outlines the main features of a design presently being completed in study form for a new generation of Polaris star sensors. The sensors are intended for attitude sensing in geosynchronous satellites; the study is being conducted at Sira Institute on behalf of the European Space Agency. The sensors will use a CCD imager for compactness, reliability and geometrical stability. The signal processing includes background subtraction, response and dark-level non-uniformity correction, and selective acquisition of digitised image data. The digitised data are used to calculate energy distribution in the image allowing star position to be located to greater accuracy than permitted by the geometric resolution of the array. The target accuracy for the sensor is 30 seconds of arc in a 4 degree field of view, to be capable of improvement to 10 seconds of arc with calibration: this has to be achieved within very tight constraints on mass and power consumption. High reliability is required over a five-year mission life. Some of the trade-offs leading to an optimisation of the design within these limitations are discussed. The results of experimental evaluation of critical detector characteristics carried out at the Institute are outlined.© (1979) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only. |