Payloads : 2. Hyper-Spectral Imager (HySI)

The Hyper-spectral imager is designed to mapthe major minerals present on the Moon (such asolivines, pyroxenes, feldspars, water-ice) with highspatial resolution and determine their composition.It employs a wedge filter sensitive in the range of0.4 to 0.92 um having 64 continuous bands with aspectral resolution of about 15 nm. It will have aspatial resolution of 80m with a swath of 20 km.The wedge filter is an interference filter varyingin thickness along one dimension. The signal isreceived by an area array detector such that differentpixels in a row of the 256 X 512 APS detectorwill receive irradiance from the same spectralregion but different spatial regions in the acrosstrack direction and different columns will receiveChandrayaan-1: Science goals 705irradiance from different spectral as well as spatialregions in the along track direction. The imagerworks in a push broom mode. This instrumentalso depends on the solar illumination and, thereforean imaging strategy depending on the solaraspect angle, has been developed.