CH-2’s Latest Dataset Can Throw More Light on Polar Regions & Water on Moon
ISRO has released a new set of advanced data products derived from the Chandrayaan-2 (CH-2) mission's radar observations, offering unprecedented insights into the Moon's polar regions and potential water-ice deposits. These datasets, generated using the Dual Frequency Synthetic Aperture Radar (DFSAR) onboard the CH-2 orbiter, provide high-resolution, full-polarimetric data, marking a significant leap in lunar surface and subsurface property analysis.
Since 2019, the CH-2 orbiter has been circling the Moon, diligently gathering high-quality data. The DFSAR, a pioneering instrument, has mapped the Moon using L-band in full-polarimetric mode at an impressive resolution of 25 meters per pixel. This advanced radar system transmits and receives signals in both vertical and horizontal directions, making it exceptionally well-suited for examining the Moon's surface characteristics.
Scientists at the Space Applications Centre (SAC) in Ahmedabad have processed approximately 1,400 radar datasets to create polarimetric mosaics covering latitudes 80 to 90 degrees in both hemispheres. These mosaics include key radar parameters such as Circular Polarisation Ratio (CPR), Single bounce Eigenvalue Relative Difference (SERD), T-Ratio, and polarimetric decomposition components. CPR indicates the possible presence of water-ice, SERD represents surface roughness, T-Ratio is related to the dielectric constant of the material, and polarimetric decomposition components highlight different types of radar scattering.
The derived data products offer valuable information on potential water-ice deposits, surface roughness, and dielectric constant, which is a measure of surface density and porosity. ISRO has developed the algorithms for analyzing the full-polarimetric data indigenously, ensuring ready-to-use outputs for the scientific community.
These advanced data products are significant for gathering first-order information about the Moon's polar regions, which are believed to have preserved the early chemical conditions of the solar system. These regions offer crucial clues to understanding the evolution of planetary bodies. The availability of such ready-to-use data on lunar polar regions is highly sought after, as it provides holistic information to characterize these areas for future lunar exploration.
The data products complement existing hyperspectral observations, enabling researchers to study mineral distributions and surface characteristics more comprehensively. The polar mosaics incorporate radar parameters that reveal the physical and electrical characteristics of the Moon's surface and subsurface. ISRO emphasizes that this is a crucial resource for understanding the Moon's polar regions.
Chandrayaan-2 has already confirmed the presence of water ice in the permanently shadowed regions of the Moon. The DFSAR instrument has the capability of peering inside the lunar surface up to a few meters depth. The mission has identified potential "dirty ice" patches, which are ice crystals mixed with regolith, within the Cabeus crater near the Moon's South Pole.
These findings are critical for future lunar missions, enhancing our understanding of the lunar surface's scattering properties and improving the precision and interpretation of radar measurements. ISRO is also planning to integrate data from the Chandrayaan-2’s Imaging IR Spectrometer (IIRS) to bolster the capability in identifying potential water-ice deposits.
The datasets are freely available to the global scientific community through ISRO's PRADAN data portal at the Indian Space Science Data Centre (ISSDC) and can be visualised via the CH2 MapBrowse platform. ISRO has invited researchers to explore the data and use it for advancing lunar science and understanding the Moon's evolution.
