The star sensor is a high-precision attitude measurement device widely used in aerospace vehicles. One of the most significant influence on the accuracy of star sensor is the operating temperature. Experiments show that with the increase of temperature, the dark current noise of CMOS increases exponentially, which greatly reduces the Signal-to-Noise ratio(SNR) of the star map. A novel and efficient thermal control design is presented in this manuscript, for the purpose of keeping the temperature of CMOS and temperature fluctuation in a limited range. To validate the design, thermal analysis of the model of CMOS assemblies are built by utilizing finite element method. During orbital operation, the temperature of the optical system of the star sensor is unevenly distributed. The structural parameters such as the refractive index of the lens, the thickness of the lens, and the curvature radius will change, affecting the imaging position and energy distribution of the star point. Star point extraction and positioning accuracy will be greatly affected. These jobs could give some guidance and reference for the precise thermal control of CMOS assembly of other space optical camera.
Star tracker is the most accurate attitude sensor for satellite. Generally speaking, the higher the
accuracy, the fainter the star can be sensed by the star tracker. How to extract the faint star from a star
image is becoming a critical technology in dynamic condition for star tracker, especially using the APS
(Active Pixels Sensor) detector. A novel APS star tracker with MEMS Gyroscope aided system was
proposed in this paper that could extremely improve the detection effect and capability for the faint
stars. During the exposure time of star tracker, the trajectory of star projection on the detector maybe
occupy more than ten pixels due to the satellite rotation. In this situation, the signal-to-noise ratio will
decline sharply, and the traditional star extraction method for faint star will take no effect. As a result,
the accuracy of star tracker would decline sharply, even more, couldn’t work. Using the MEMS
Gyroscope, the track of star projection can be predicated and measured, on the basis of which the
deconvolution algorithm could be taken to recover the faint star signal. The accuracy of the star
projection centroid could be improved obviously, and the dynamic performance of the star tracker
would be improved by a magnitude. Meanwhile, the MEMS gyroscope has not less volume, mass and
power consumption, which make it more suitable for the application of APS star tracker.