Articles written in Journal of Earth System Science

    • Mini-RF S-band observation of Ohm and Stevinus craters using circular polarization ratio and m-chi decomposition techniques


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      The aim of the study was to observe two lunar impact craters of Copernican age, Ohm ($\rm{18.4^{\circ}N, 113.5^{\circ}W}$) and Stevinus ($\rm{32.5^{\circ}S, 54.2^{\circ}E}$) under microwave radar data of Miniature Radio Frequency (Mini-RF), an instrument onboard Lunar Reconnaissance Orbiter (LRO) of NASA, where Ohm is located on the far side of the Moon and Stevinus is situated on the near side of the Moon. We have analyzed the characters of impact ejecta melt of both the craters in radar data which are not evidently distinguished in the high resolution optical data of narrow angle camera (NAC) and wide angle camera (WAC) of LRO mission. Circular polarization ratio (CPR) and m-chi decomposition images were developed using ENVI and ArcGIS software which were used to understand surface roughness and backscattering properties of Ohm and Stevinus craters. Both the craters evidently have high CPR values indicating either exposure of fresh material or elevated surface roughness due to surface geometry. The m-chi decomposition of Ohm and Stevinus craters shows dominant yellowish hue suggesting a backscatter combination of double-bounce (db) scattering and volume scattering (vs) in contrast to the surrounding terrain which shows Bragg scattering (bs) according to the 7-fold classification colour-wheel. Using available optical and Mini-RF data geological maps of both the craters were generated including features such as boundary of ejecta blanket, ejecta boulders and mass wasting in the crater.

    • Compositional and morphological analysis of Gassendi crater


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      Gassendi impact crater is located on the western side of the visible lunar hemisphere just north of Mare Humorum. It has a diameter of 110 km, and it is a Floor Fractured Crater (FFC) belonging to Class-3 type that exhibits a wide annular depression or moat. Is Gassendi crater formed due to igneous intrusion or viscous relaxation? To investigate this, the analysis explores the compositional and morphological dimensions of the crater. The area studied has been found to contain various minerals such as LCP (Low Calcium Pyroxene), HCP (High Calcium Pyroxene), olivine, plagioclase, and mixtures of pyroxene and plagioclase. To differentiate between similar spectral profiles, Integrated Band Depth map (IBD) and Band Depth Parameter (BD) maps are generated using the M$^{3}$ data. Features such as central peak complex, isolated mound, fractures, rimae, wall terraces, wall slumps, etc., have been identified and marked in the morphological map. We have also studied the morphometrical aspects of all the morphological features. Another impact crater just on the northern rim of Gassendi, Gassendi A crater shows the presence of LCP and olivine mineral along with extensive slumping, melt pool, and distorted northern rim. We have mapped the three mare regions towards the south of the crater floor and estimated their ages by using the CSFD technique. The present appearance of the Gassendi crater is mostly due to past volcanic activities rather than the result of the impact event.

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