NOPR Collection:

Remote sensing of lunar surface

2021-06-07T10:21:26Z

Title: Remote sensing of lunar surface Authors: Calla, Om Prakash Narayan; Sharma, Vishwa Abstract: Remote Sensing of Lunar Surface has provided its Topographic, Geo-chemical composition, Radiation dose and Mineralogical information of Lunar Surface. The Indian Space Research Organisation's (ISRO) Chandrayaan-1 and National Aeronautical Space Administration's (NASA) Lunar Reconnaissance Orbiter (LRO) have different type of sensors for measuring and mapping of the entire Lunar Surface. For the Mapping of Topographical features Chandrayaan-1 has Terrain Mapping Camera (TMC), while Lunar Reconnaissance Orbiter (LRO) has Lunar Reconnaissance Orbiter Camera (LROC).
For determination of Chemical and Mineralogical features Chandrayaan-1 has Lunar Laser Ranging Instrument (LLRI) and Lunar Reconnaissance Orbiter (LRO) has Lunar Orbiter Laser Altimeter (LOLA) instrument. The mapping of Geo-chemicals has been done by Chandryaan-1 X-ray spectrometer (C1XS) and High Energy X-ray Spectrometer (HEX) onboard Chandrayaan-1 and Lunar Exploration Neutron Detector (LEND) onboard Lunar Reconnaissance Orbiter (LRO). The knowledge of mineral composition has been used for getting information about the evolution history of Moon. For this purpose the Chandrayaan-1 has Hyper Spectral Imager (HySI), near Infrared Spectrometer (SIR-2) and Moon Mineralogical Mapper (M³) and Lunar Reconnaissance Orbiter (LRO) has Lyman alpha Mapping Project (LAMP).
Radiation dose measurement is also important for designing the sensors and future manned missions. Therefore, Chandrayaan-1 has Radiation Dose Monitor (RADOM) and Lunar Reconnaissance Orbiter (LRO) has Cosmic Ray Telescope for determination of the Effect of Radiation (CRaTER). For the measurement of Backscattered or Energetic Neutral Atoms (ENAs) and predetermination of surface for future landing missions Chandrayaan-1 has Subatomic Reflection Analyser (SARA) and Moon Impactor Probe respectively along with the other payloads. The LRO has the Diviner Lunar Radiometer Experiment (DLRE) for measuring the temperature fluctuations, rough terrain and other landing hazards similar to Moon Impactor Probe (MIP) onboard Chandrayaan-1.
The active microwave sensors Miniature Synthetic Aperture Radar (Mini-SAR) onboard Chandrayaan-1 and Mini-RF onboard Lunar Reconnaissance Orbiter (LRO) have been used for identifying the traces of water in form of ice in the permanently shadowed regions at the poles of the Moon. The Mini-SAR instrument onboard Chandrayaan-1 has a primary antenna which transmits single right circularly polarized signal and receives the dual polarized (Left and Right) signal. While the antenna of Miniature Radio Frequency Radar (Mini-RF) onboard LRO transmits either left or right circularly polarized signal and then receives horizontal and vertical polarized signals.
The observations based on Circular Polarization Ratio (CPR>1) as well as m-chi (0 to 0.2) parameters and backscattering coefficient less than -15dB have helped in determining the presence of water-ice, differentiate the water-ice from rock abundances, surface and sub-surface characteristics for identifying the Possible landing sites for the future lunar missions. Quantification of water-ice in the Hermite-A crater gives the confirmation that only Circular Polarization Ratio (CPR) is not sufficient for identifying water-ice. The other parameters like m-chi and backscattering coefficient values must be taken into the consideration for distinguishing between water-ice and rocky terrains. The Dielectric properties of Terrestrial Analogue of Lunar Soil (TALS) have been studied and compared with the Apollo samples at different microwave frequencies. The study of variations in complex permittivity of TALS having different percentages of water has been done at different temperatures.
The variable Permittivity mapping of lunar surface has been done by using datasets of Microwave Radiometer (MRM) onboard Chang'e-1 and Diviner onboard LRO. The success of Chandrayaan-1 and Lunar Reconnaissance Orbiter (LRO) has greatly helped Scientist to go for further investigations in the areas of water-ice using microwave sensors for future missions for exploration the Moon. Page(s): 59-78

Multiband reconfigurable antennas for future wireless communication systems

2021-06-07T10:13:38Z

Title: Multiband reconfigurable antennas for future wireless communication systems Authors: Dalal, Kusum; Singh, Tejbir; Singh, Pawan Kumar Abstract: Evolution in wireless technology has resulted in remarkable capabilities, but ever increasing user demand and limited bandwidth spectrum has always instigated the researchers to think of new techniques that can improve network efficiency in terms of size, power and bandwidth consumption. Antenna designing is one of the key factors in achieving this goal and as a result plethora of research work has been conducted in past for crafting sustainable reconfigurable multiband antennas for different wireless services. The concept of combining the wideband-narrowband reconfiguration functionality into a single antenna has created an effective solution for optimizing antenna size and enhancing flexibility in antenna designing. Moreover; this combination has offered the advantage of pre-filtering, which has helped in mitigating the level of interference at the receiver end and has provided an edge over the fixed or non-reconfigurable transceivers. This paper has presented a detailed outlook about reconfigurable antennas and the various techniques involved in attaining reconfigurability in antenna design. The review has been supported by some antenna designs and simulation results that have provided an insight into reconfiguration features. Some new technologies employed in antenna design have also been briefly presented. Page(s): 79-97

Discrimination of Arctic multi-year ice from first-year ice using SCATSAT-1 data

2021-06-07T10:11:17Z

Title: Discrimination of Arctic multi-year ice from first-year ice using SCATSAT-1 data Authors: Singh, Khoisnam Nanaoba; Singh, Urikhinbam Somas; Singh, Rajkumar Kamaljit Abstract: The distinctive dielectric properties of multi-year ice that make it stand out from the first-year ice has been exploited in this study to discriminate the Arctic multi-year ice from the first-year ice. We have used the backscattering coefficient, the brightness temperature and the gamma-naught data from the ISRO's miniature satellite SCATSAT-1 for this study. Principal component analysis in conjunction with the ISODATA unsupervised classification technique has been used to achieve the goal of this study. The classification results so obtained have been compared with a well-established sea ice type data product from the EUMETSAT's Ocean & Sea Ice Satellite Application Facility. Moreover, we have employed a change detection technique to ascertain the changes in the Arctic multi-year ice for the SCATSAT-1 period 2016 through 2018 (autumn and spring changes). Page(s): 98-104

An Integrated system for study of the local atmospheric currents and electric fields at a high altitude station at Shillong

2021-06-07T10:09:07Z

Title: An Integrated system for study of the local atmospheric currents and electric fields at a high altitude station at Shillong Authors: Valeo, Visuzoto; Koparkar, Pramila Vinayak Abstract: This program has been initiated to study the atmospheric and meteorological parameters at a high altitude sub Himalayan location (Shillong25.58°N, 91.89°E), Shillong, Meghalaya to understand their interaction and bearing on the local climate. Design and fabrication of the integrated instrumentation for measurement and recording of atmospheric electric potential gradient, point discharge current, solar irradiance and meteorological parameters was implemented. The results obtained indicate satisfactorily the performance of the instrument in fair-weather and disturbed weather conditions. Page(s): 105-109