Low-cost satellite attitude control sensors based on integrated infrared detector arrays

This paper describes attitude control systems (ACS) for satellites and a new, static system based on an integrated infrared (IR) detector array. After a short introduction on the use and control of satellites in general, we explain the advantage of static systems, made possible by the use of integrated IR detector arrays. In particular, the static system is lighter and smaller than the previous systems, and requires less power. The electronics is updated to state-of-the art, increasing the autonomy of the system and thereby reducing its dependence upon the satellite microcontroller. The detectors are based on a bipolar silicon process for the mechanical structure (using electrochemically controlled etching (ECE)-potassium hydroxide (KOH) etching), with an SiN membrane for thermal isolation of the pixels, which have a polymer black coating for transduction of radiation to heat and n-type versus p-type polysilicon thermopiles for heat detection. The pixel pitch is 600 mum, the black area is approximately 495 x 440 mum(2), and the pixel sensitivity is approximately 55 V/W, at a thermopile resistance of 23 kOmega. Two types of detectors have been designed: a single-array type with 32 pixels in two staggered arrays, and a chip with four 32-pixel arrays integrated in a cross. This has made it possible to make a family of earth sensors for the different missions in space.