Circular Polarization Characteristics of South Polar Lunar Craters using Chandrayaan-1 Mini-SAR and LRO Mini-RF

Abstract

The paper presents a case study of inconsistent behaviour of Chandrayaan-1 Mini-SAR and LRO Mini-RF data over south polar lunar craters. The paper includes analysis of Stokes parameters and characterization of received time-varying electromagnetic fields over the south pole lunar craters. For the study, Chandrayaan-1 Mini-SAR and LRO Mini-RF data at 2.38 GHz are used. Total five lunar craters in south polar region are analyzed to study the effect of various parameters on the polarization of the signal. We have compared linear horizontal (LH) and linear vertical (LV) polarization components of received radar signal over the same targets using two different SAR data. Ratios of received LH to LV components are also derived over the five craters. It is observed that Chandrayaan-1 Mini-SAR is receiving high LH component as compared to LV component. This is not consistent with the scattering theory (Fawwaz et al. in Microwave remote sensing active and passive, Artech House Inc., New York, 1981), which states that for incidence angle greater than 15°, the vertical polarized component of a received signal should be always high as compared to horizontal polarized component over rough surfaces. These inconsistent results of Chandrayaan-1 Mini-SAR are observed over all five craters. In the paper, various effects of sensor parameters like incident angle, ellipticity angle, orientation angle etc. on scattering mechanism are discussed to understand the inconsistent behaviour of two SAR data over same target.

Dielectric characterization and polarimetric analysis of lunar north polar crater Hermite-A using Chandrayaan-1 Mini-SAR, Lunar Reconnaissance Orbiter (LRO) Mini-RF, and Chandrayaan-2 DFSAR data

“…Calla et al (2016) showed using the Terrestrial Analogue of Lunar Soil (TALS), values of the dielectric constant were found to be fairly close to those observed at the Apollo-17 landing site, Taurus Littrow valley (Calla et al, 2014a(Calla et al, , 2016. It was suggested by Calla et al (2015) that the variation in received LH and LV components is affected by polarization states (same sense-SC and opposite sense-OC), as well as polarization parameters (m, delta-d, chiv, CPR) (Calla et al, 2015).…”

“…In higher CPR values (>1), one can expect double-bounce scattering or volume scattering as a result of the small size particles made up of the lava flow (Calla et al, 2014b). As stated earlier that CPR is a key parameter to determine the presence of water ice content if the values of CPR are high (Calla et al, 2015;Mohan et al, 2013). The areas which show CPR less than unity act as a Braggs scattering surface (Shukla and Kumar, 2018).…”

Time–Frequency Attribute Analysis of Channel 1 Data of Lunar Penetrating Radar

“…The Mini-RF instrument on the Lunar Reconnaissance Orbiter (LRO) is a SAR, and it works with bistatic radar from the Arecibo Observatory to conduct data analysis of the region. The results show that there may be near-surface sediments of water ice [4,5].…”

“…The small SAR was launched on the moon in September 2007 and it carried out the Indian Chandrayaan mission. It mapped the scattering characteristics of the moon's pole and determined the existence and extent of polar ice [3,4]. The Mini-RF instrument on the Lunar Reconnaissance Orbiter (LRO) is a SAR, and it works with bistatic radar from the Arecibo Observatory to conduct data analysis of the region.…”