• A S Kiran Kumar

      Articles written in Journal of Earth System Science

    • Terrain mapping camera for Chandrayaan-1

      A S Kiran Kumar A Roy Chowdhury

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      The Terrain Mapping Camera (TMC) on India’s first satellite for lunar exploration, Chandrayaan-1, is for generating high-resolution 3-dimensional maps of the Moon. With this instrument, a complete topographic map of the Moon with 5 m spatial resolution and 10-bit quantization will be available for scientific studies. The TMC will image within the panchromatic spectral band of 0.4 to 0.9 Μm with a stereo view in the fore, nadir and aft directions of the spacecraft movement and have a B/H ratio of 1. The swath coverage will be 20 km. The camera is configured for imaging in the push broom-mode with three linear detectors in the image plane. The camera will have four gain settings to cover the varying illumination conditions of the Moon. Additionally, a provision of imaging with reduced resolution, for improving Signal-to-Noise Ratio (SNR) in polar regions, which have poor illumination conditions throughout, has been made. SNR of better than 100 is expected in the ±60° latitude region for mature mare soil, which is one of the darkest regions on the lunar surface. This paper presents a brief description of the TMC instrument.

    • Hyper-Spectral Imager in visible and near-infrared band for lunar compositional mapping

      A S Kiran Kumar A Roy Chowdhury

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      India’s first lunar mission, Chandrayaan-1, will have a Hyper-Spectral Imager in the visible and near-infrared spectral bands along with other instruments. The instrument will enable mineralogical mapping of the Moon’s crust in a large number of spectral channels. The planned Hyper-Spectral Imager will be the first instrument to map the lunar surface with the capability of resolving the spectral region, 0.4 to 0.92 Μm, in 64 continuous bands with a resolution of better than 15 nm and a spatial resolution of 80 m. Spectral separation will be done using a wedge filter and the image will be mapped onto an area detector. The detector output will be processed in the front-end processor to generate the 64-band data with 12-bit quantization. This paper gives a description of the Hyper-Spectral Imager instrument.

    • Detection of Mg spinel lithologies on central peak of crater Theophilus using Moon Mineralogy Mapper (M3) data from Chandrayaan-1

      D Lal P Chauhan R D Shah S Bhattacharya Ajai A S Kiran Kumar

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      Spectral reflectance data derived from Moon Mineralogy Mapper (M3) onboard India’s Chandrayaan-1 has revealed Fe bearing Mg-spinel-rich lithology on central peaks of the crater Theophilus. These newly identified Fe bearing Mg-spinel-rich rock types are defined by their strong 2-𝜇m absorption and lack of 1-𝜇m absorptions in spectral reflectance response. Such lithology has been reported previously along the inner ring of Moscoviense Basin on the lunar far side. The Modified Gaussian Modeling (MGM) analysis of the Fe bearing Mg-spinel reflectance spectra has been done and the results of the analysis clearly bring out a strong spectral absorption at 1872 nm with no significant absortion around 1000 nm. The presence of spinel group of minerals in the Theophilus central peak and the fact that central peaks mostly represent uplifted mass of deep crustal material confirm that central peaks can be used as a window to study the deep crustal and/or upper mantle composition and may lead to a fresh perspective about the crustal composition of Moon.

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