| Hyper Spectral Imager (HySI) |
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| Scientific Objective: |
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| To obtain spectroscopic data for mineralogical mapping of the lunar surface. The data from this instrument will help in improving the available information on mineral composition of the surface of Moon. Also, the study of data in deep crater regions/central peaks, which represents lower crust or upper mantle material, will help in understanding the mineralogical composition of Moon’s interior. |
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| Payload Configuration Details: |
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| The uniqueness of the HySI is in its capability of mapping the lunar surface in 64 contiguous bands in the VNIR, the spectral range of 0.4-0.95 µm region with a spectral resolution of better than 15 nm and spatial resolution of 80 m, with swath coverage of 20 km. HySI will collect the Sun’s reflected light from the Moon’s surface through a tele-centric refractive optics and focus on to an APS area detector for this purpose. |
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| The dispersion is achieved by using a wedge filter so as to reduce the weight and compactness of the system compared to using a prism / grating. The wedge filter is an interference filter with varying thickness along one dimension so that the transmitted spectral range varies in that direction. The wedge filter will be placed in close proximity to an area detector. Thus, different pixels in a row of the detector will be receiving irradiance from the same spectral region but different spatial regions in the across track direction. In the column direction of the detector, different rows will receive irradiance of different spectral as well as spatial regions in the along track direction. The full spectrum of a target is obtained by acquiring image data in push broom mode, as the satellite moves along the column direction of the detector. An Active Pixel Sensor (APS) area array detector with built-in digitizer would map the spectral bands. The payload mass is 2.5 kg and its size is 275 mm x 255 mm x 205 mm. |
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| HySI payload is developed by ISRO |
