The proposed horizon sensor uses a dual set of pyroelectric arrays to provide satellite pitch and roll information regardless of sun/moon effects while at the same time automatically minimizing radiance errors.The MiDES (Miniature Dual Earth Sensor) is designed to provide horizon position information for Low Earth Orbiting (LEO) satellites using two sets of 16 element linear arrays mounted 90 degrees apart in the imaging plane. The Sensor operates in the 15 micron IR wavelength band and covers a field of view of 28 degrees (+/-14 degrees). Through the use of dual sets of pyroelectric arrays, the MiDES Earth sensor has automatic Sun/Moon rejection. In addition, radiance errors are minimized by actually measuring the radiance of the Earth just below the Earth crossing.High accuracy (better than 0.1 degrees) of the device is achieved using high sensitivity, heritage-proven Lithium Tantalate (LTO) pyroelectric detectors. Longevity is achieved by eliminating a motor and bearing assembly, common to other scanning Earth sensors and replacing it with a low power "tuning fork" type shutter mechanism. In addition to increased reliability, the elimination of the motor greatly reduces the weight and the power required to operate the device.The proposed horizon earth sensor is well suited for the various LEO communications satellite constellations that are being proposed by several groups. These groups include Iridium, Globalstar, Oddesy, Orbcom, Starsys and Elipsat, plus various foreign constellations. In addition the arrays and the chopping method employed have applications in the automotive industry for smart vehicles and the gas industry for leak detection.
Keywords: Phase_I, NASA, Abstract, FY94
