The Indian Space Research Organization (ISRO) began India’s planetary exploration program with the successful launch of Chandrayaan-1 orbiter mission to the Moon in 2008. The eleven remote-sensing scientific instruments from ISRO, NASA and ESA onboard Chandrayaan-1 have made significant findings including discovery of water signature, spinel minerals, lunar lava tubes, evidences of recent volcanism, impact-triggered boulder movements and discovery of sputtered atomic oxygen and backscattered helium on the lunar surface. The first Indian inter-planetary mission, Mars Orbiter Mission (MOM) with five science payloads was successfully launched by a PSLV rocket on November 5, 2013 and entered an elliptical orbit around planet Mars on September 24, 2014. The Mars Orbiter is currently observing Mars surface features, morphology, mineralogy and the Martian atmosphere. The Chandrayaan-2 spacecraft to the Moon is a composite module consisting of Orbiter, Lander and Rover. Chandrayaan-2 Mission is planned to be launched onboard Geosynchronous Satellite Launch Vehicle (GSLV) during first quarter of 2018. The Orbiter will carry the combined stack up to moon till the Lunar Orbit Insertion (LOI). The combined stack is then inserted into a lunar orbit of 100 km x 100 km. The Lander with the Rover is then planned to be separated from the Orbiter for soft-landing on a site near south polar lunar surface. This paper presents an overview of the technology and science objectives of India’s Chandrayaan-2 Mission to the Moon, spacecraft architecture, science instruments, launch vehicle, mission design and operations.

Overview and Technical Architecture of India's Chandrayaan-2 Mission to the Moon

Chandrayaan-2 Dual-frequency Synthetic Aperture Radar (DFSAR): Performance Characterization and Initial Results

http://manuscript.elsevier.com/S0273117722000758/pdf/S0273117722000758.pdf

Polarimetric Analysis of L-band DFSAR data of Chandrayaan-2 Mission for Ice Detection in Permanently Shadowed Regions (PSRs) of Lunar South Polar Craters

Transmit wave polarization (i.e., ellipticity and roll) deviation from the ideal or intended transmit mode affects compact polarimetry (CP) products and associated data exploitation. Hence, it is important to evaluate such effects on the CP model and account for the associated variations through data exploitations. This letter explores an approach to model and estimate ellipticity variations for calibration by taking advantage of a variational model and adjoint polarimetric synthetic aperture radar data.

A Tool for Analysis and Calibration of Compact Polarimetry SAR Mode Anomaly

A new dielectric constant estimation approach for the lunar surface using Mini-RF synthetic aperture radar (SAR) data and Chandrayaan-2 SAR data is presented in this work. Both the SAR systems are based on a hybrid-polarimetry (hybrid-pol) configuration that transmits a circularly polarized wave and coherently measures the backscattered wave by dual orthogonal linearly polarized channels. From the three-component hybrid-pol SAR decomposition technique, the ratio of the Fresnel reflection coefficients for horizontal and vertical polarization transmission can be estimated. This ratio, which is referred to as the co-polarization ratio, is used by the proposed methodology to find the real value of the dielectric constant. For performance validation, the proposed method is implemented on the Mini-RF hybrid-pol SAR data acquired over Apollo 17 landing sites. The values of the real part of dielectric constant are estimated for six different regions covering the collection sites of six Apollo 17 samples: 72 441, 73 241, 74 241, 75 081, 76 001, and 79 135. The results obtained using the proposed method are found to be in good agreement with the laboratory-measured results of the corresponding samples. Furthermore, the proposed methodology is also implemented on the Chandrayaan-2 hybrid-pol SAR data acquired over the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Biot crater</i> region. Various small areas possessing different possible surface characteristics, situated inside and outside the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Biot crater</i> , are being analyzed for validation. 

J. G. Vachhani

Papers

Chandrayaan-2 dual-frequency SAR: Further investigation into lunar water and regolith