We successfully observed 191 near-Earth asteroids using the Arecibo Observatory’s S-band planetar... more We successfully observed 191 near-Earth asteroids using the Arecibo Observatory’s S-band planetary radar system from 2017 December through 2019 December. We present radar cross sections for 167 asteroids; circular-polarization ratios for 112 asteroids based on Doppler-echo-power spectra measurements; and radar albedos, constraints on size and spin periods, and surface-feature and shape evaluation for 37 selected asteroids using delay-Doppler radar images with a range resolution of 75 m or finer. Out of 33 asteroids with an estimated effective diameter of at least 200 m and sufficient image quality to give clues of the shape, at least 4 (∼12%) are binary asteroids, including 1 equal-mass binary asteroid, 2017 YE5, and at least 10 (∼30%) are contact-binary asteroids. For 5 out of 112 asteroids with reliable measurements in both circular polarizations, we measured circular-polarization ratios greater than 1.0, which could indicate that they are E-type asteroids, while the mean and the ...
Ground-based planetary radar observations first revealed deposits of potentially nearly pure wate... more Ground-based planetary radar observations first revealed deposits of potentially nearly pure water ice in some permanently shadowed regions (PSRs) on Mercury’s poles. Later, the MESSENGER spacecraft confirmed the icy nature of the deposits, as well as their location within PSRs. Considering the geologic context provided by MESSENGER, we further characterized the north polar deposits by pairing spacecraft data with new Arecibo S-band radar observations. Here we show that some ice deposits within PSRs have a gradational pattern in their radar properties that is likely associated with differences in ice purity. Radar-bright features with a circular polarization ratio μ c > 1 can be characterized by water ice with ≳3% impurities by volume while those with μ c < 1 by ≳20% impurities. Furthermore, areas in PSRs with μ c < 1 typically surround locations of stronger radar backscatter with μ c > 1. Therefore, deposits of nearly pure water ice are likely surrounded by lower-purity...
This set of 36 FITS images of radar observations of near-Earth asteroids includes image data pres... more This set of 36 FITS images of radar observations of near-Earth asteroids includes image data presented in a publication in revision: Virkki et al. Arecibo Planetary Radar Observations of Near-Earth Asteroids: 2017 December - 2019 December<br><br>Delay-Doppler images are processed and displayed as echo-power z-score normalized values in the range (directly proportional to time delay) and Doppler frequency space. The images have not been enhanced in contrast or brightness beyond setting negative values to zero in a few cases.<br>The included near-Earth asteroids and their range (vertical) and frequency (horizontal) resolutions are:(3752) Camillo, 75 m/px, 0.061 Hz/px;(13553) Masaakikoyama, 75 m/px, 0.119 Hz/px;(66391) Moshup, 30 m/px, 0.297 Hz/px;(66347) 2001 KB67, 7.5 m/px, 0.0336 Hz/px;(68950) 2002 QF15, 7.5 m/px, 0.00938 Hz/px;(90403) 2003 YE45, 75 m/px, 0.00745 Hz/px;(141593) 2002 HK12, 7.5 m/px, 0.0373 Hz/px;(144332) 2004 DV24, 7.5 m/px, 0.0745 Hz/px;(153814) 20...
The Dual-Frequency synthetic aperture radar (DFSAR) system manifested on the Chandrayaan-2 spacec... more The Dual-Frequency synthetic aperture radar (DFSAR) system manifested on the Chandrayaan-2 spacecraft represents a significant step forward in radar exploration of solid solar system objects. It combines SAR at two wavelengths (L- and S-bands) and multiple resolutions with several polarimetric modes in one lightweight (∼ 20 kg) package. The resulting data from DFSAR support calculation of the 2×2 complex scattering matrix for each resolution cell, which enables lunar near surface characterization in terms of radar polarization properties at different wavelengths and incidence angles. In this paper, we report on the calibration and preliminary performance characterization of DFSAR data based on the analysis of a sample set of crater regions on the Moon. Our calibration analysis provided a means to compare on-orbit performance with pre-launch measurements and the results matched with the pre-launch expected values. Our initial results show that craters in both permanently shadowed reg...
Introduction: High radar reflectivity has been linked to thick water ice deposits in some Solar S... more Introduction: High radar reflectivity has been linked to thick water ice deposits in some Solar System objects such as the permanently shadowed polar regions (PSRs) of Mercury and Jovian satellites [1-3]. However, radar detection of water ice in the permanently shadowed regions near the poles of the Moon has been a topic of intense debate since several years [4-7]. Apart from the ground-based planetary radar systems, since 2008, two orbital miniature synthetic aperture radars on the Chandrayaan-1 and Lunar Reconnaissance Orbiter (LRO) missions (Mini-SAR and Mini-RF respectively) have imaged the lunar surface with the main purpose of detecting the distinctive radar polarimetric signature of ice deposits at the lunar poles. Both ground-based and orbital-based high resolution radar data showed that the anomalously high radar reflectivity observed from PSRs on the Moon is not unique to the poles, and also suggested a source other than accumulations of thick water ice deposits (e.g. [6-8...
Introduction: Basaltic volcanism was once common on the Moon and is responsible for the lunar mar... more Introduction: Basaltic volcanism was once common on the Moon and is responsible for the lunar maria that covers 17% of the lunar surface [1], mostly filling the near-side basins. Volcanic features on the Moon include domes, cones, rilles, collapsed lava tubes, depressions, and pyroclastic deposits [e.g. 2, 3]. As indicated in numerous previous analyses, many possible lunar landing sites are in volcanic regions, so it is very important to ascertain their physical properties prior to landing and in-situ sampling. The lunar volcanic domes are particularly interesting as they are shown to have a variety of geologic properties [e.g. 2, 3, 4]. Here, we utilize data sets from LRO including the Mini-RF radar, LROC, and the Diviner Lunar Radiometer, to investigate the morphology, composition, and structure of some volcanic domes and related depressions, with the goal of better characterizing the style of regional volcanism that led to the formation of these constructs. Data and Methods: We a...
Introduction: The L&S band Dual-Frequency Synthetic Aperture Radar (DFSAR) onboard Chandrayaan-2 ... more Introduction: The L&S band Dual-Frequency Synthetic Aperture Radar (DFSAR) onboard Chandrayaan-2 orbiter, is the first fully (quad) polarimetric SAR system in the lunar orbit [1]. The architecture of this radar instrument supports multiple polarimetric modes of operation. DFSAR observations contribute significantly towards understanding the origin and evolution of lunar impact craters [2]. In the present study, we exhibit some initial results obtained from DFSAR L-band Full-Polarimetric (FP) observations towards understanding physical behaviour of two different groups of impact craters. Study Area and Data Used: L-band FP SAR observations obtained at 26o incidence angle over secondary craters situated on the floor of Peary Crater (87.9oN, 35.3oE) in the lunar north polar region are analysed. This region consists of one young, fresh crater and two craters that were classified as CPR anomalous craters in previous studies [3] (Fig. 1). For comparison, CPR product derived from S-band zo...
We have conducted spectral and spatial analysis of the Compton–Belkovich Thorium Anomaly (61.1°N,... more We have conducted spectral and spatial analysis of the Compton–Belkovich Thorium Anomaly (61.1°N, 99.5°E) region on the far side of the Moon based on high-resolution data from recent lunar missions. Chandrayaan-1 Moon Mineralogy Mapper data of Compton–Belkovich volcanic complex (CBVC) reveal the existence of a strong doublet feature near 2800 nm throughout the volcanic construct, which could be attributed to the presence of water and/or hydroxyl in the studied site. Very high resolution Lunar Reconnaissance Orbiter Camera–Narrow Angle Camera mosaic of the study area shows that the strongest of the hydration features within the CBVC is primarily related with either sunlit inner flanks of small-sized fresh craters or fresh escarpments associated with the central collapse structure. Moreover, Mini-RF Synthetic Aperture Radar data from Lunar Reconnaissance Orbiter mission suggests the presence of a thick pyroclastic deposit in the volcanic complex. Our study indicates that the enhanced hydration at CBVC could possibly have originated from the episodic events of eruption and effusion involving silicic magma, which could probably be responsible for the tapping of a zoned magma body with a water-rich cap. Morphology of CBVC also confirms the presence of episodic effusive and eruptive events that probably had led to the formation of elevated topography, central collapsed feature and late eruptive domes in the study area.
Volcanic calderas are found on Earth, Mars, Venus and Io, and are rare, but unique volcanic struc... more Volcanic calderas are found on Earth, Mars, Venus and Io, and are rare, but unique volcanic structures in the Solar System. Compton-Belkovich Volcanic Complex (CBVC) (60.5°N-99.5°E) on the far side of the Moon is a unique non-mare feature due to its evolved lithology, regional tectonic setting, its location being near the north pole, far from the Procellarum KREEP Terrane (PKT) and its recent association with endogenic water. High-resolution remote sensing observations of several structural features at CBVC such as ring faults, radial faults, fractures manifested by various morphological features such as domes of varied sizes and shapes and pyroclastic ash flows characterize it to be a volcanic caldera. The loading of Humboldtianum basin with basalts and subsequent development of extensional structures outside it along with high-thorium anomaly and resulting silicic volcanism at CBVC producing central collapsed caldera could be considered as an analogy to silicic calderas on Earth formed in extensional tectonic regime even though the tectonic processes involved in these two cases are entirely different, the former being impact-related, whereas the latter involves rifting or hotspot-related activities associated with extensional plate tectonics. Presence of high-reflectance feature and its extension to the east-southeast of the topographic expression and its relation with pyroclastic dispersal have been supported by radarbased Mini-RF observations and high-resolution LROC-NAC imagery. It suggests the presence of a latestage fine pyroclastic layer within the CBVC region. The diverse volcanic features that exist at the studied site indicate a series of deformation and eruption events associated with silicic magmatism and thus, CBVC could be considered as an ash flow caldera on the Moon. Here, we present a detailed appraisal of various volcanic and structural features detected at CBVC through high-resolution optical as well as radar observations. Based on the previous and present studies, an evolutionary model of the area has been proposed and the petrological implications of silicic magmatic activity, its manifestation, evolution and association with endogenic water have been discussed.
The surface layer of the Moon preserves vital evidences of lunar impact and cratering processes d... more The surface layer of the Moon preserves vital evidences of lunar impact and cratering processes due to the absence of any Aeolian and fluvial erosion processes acting on it. By examining these evidences, which are recorded throughout the evolutionary history of the Moon, several basic aspects of lunar science can be understood, and this has direct relevance to the surfaces of other airless bodies within the solar system. In this study, rock abundance data obtained from Thermal Infrared (TIR) observations and radar Circular Polarization Ratio (CPR) data sets obtained from polarimetric SAR observations were correlated at some sample sites on the lunar surface. Preliminary results yielded qualitative and quantitative estimates for surface rock abundances. Except at distal ejecta deposits of young, bright craters a general correlation was observed between the two datasets. Mixed results were observed from the impact melt flows where the situation is complex due to the possible subsurface-volume and volume-subsurface interactions of the radar waves. But the flow features were clearly separated from the interior and ejecta regions of their parent craters in terms of CPR and rock abundances. The extent and distributions of pyroclastic deposits and dark haloed regions could not be distinctly identified at the resolution of datasets utilized. Near Gerasimovich D crater, the Diviner Radiometer has provided the first TIR observations of a newly discovered impact melt flow which was not visible in the optical imagery. This facilitated the first ever quantitative comparisons of the radar CPR and rock abundance values near such a region. Also, significant differences in spatial patterns between the radar and rock concentration data sets were observed, owing to the differences in the sensitivity of the two observations.
We analyzed the morphology of pre-caldera domes, central caldera, ash-flow features, post-caldera... more We analyzed the morphology of pre-caldera domes, central caldera, ash-flow features, post-caldera effusive and eruptive features at Compton-Belkovich Complex.
FUNCTION OF VIEWING GEOMETRY. S. S. Bhiravarasu1, E. G. Rivera-Valentín1, P. A. Taylor1, G. W. Pa... more FUNCTION OF VIEWING GEOMETRY. S. S. Bhiravarasu1, E. G. Rivera-Valentín1, P. A. Taylor1, G. W. Patterson2, C. D. Neish3, and B. J. Thomson4, 1Lunar and Planetary Institute, Universities Space Research Association, 3600 Bay Area Blvd, Houston, TX 77058 ([email protected]), 2Johns Hopkins Applied Physics Laboratory, Laurel, MD, 3Department of Earth Sciences, The University of Western Ontario, London, Ontario, 4Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, TN.
CHANDRAYAAN-2 DFSAR RADARS. G. W. Patterson1, S. S. Bhiravarasu2,3, L. M. Carter4, J. T. S. Cahil... more CHANDRAYAAN-2 DFSAR RADARS. G. W. Patterson1, S. S. Bhiravarasu2,3, L. M. Carter4, J. T. S. Cahill1, T. Chakraborty3, A. Das3, E. Heggy5, R. Kumar3, G. A. Morgan6, C. D. Neish7, C. A. Nypaver8, E. M. Palmer5, D. K. Pandey3, J. B. Plescia1, D. Putrevu3, A. M. Stickle1, P. A. Taylor2, B. J. Thomson8 and the Mini-RF and DFSAR teams, ,1Planetary Exploration Group, Johns Hopkins University Applied Physics Laboratory, Laurel, MD ([email protected]), 2Lunar and Planetary Institute, USRA, Houston, TX, 3Space Applications Centre (ISRO), Ahmedabad, Gujarat, India, 4Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, 5University of Southern California, Los Angeles, CA, 6Planetary Science Institute, Tucson, AZ, 7University of Western Ontario, London, ON, Canada, 8Dept. of Earth and Planetary Sciences, University of Tennessee, Knoxville, TN
We successfully observed 191 near-Earth asteroids using the Arecibo Observatory’s S-band planetar... more We successfully observed 191 near-Earth asteroids using the Arecibo Observatory’s S-band planetary radar system from 2017 December through 2019 December. We present radar cross sections for 167 asteroids; circular-polarization ratios for 112 asteroids based on Doppler-echo-power spectra measurements; and radar albedos, constraints on size and spin periods, and surface-feature and shape evaluation for 37 selected asteroids using delay-Doppler radar images with a range resolution of 75 m or finer. Out of 33 asteroids with an estimated effective diameter of at least 200 m and sufficient image quality to give clues of the shape, at least 4 (∼12%) are binary asteroids, including 1 equal-mass binary asteroid, 2017 YE5, and at least 10 (∼30%) are contact-binary asteroids. For 5 out of 112 asteroids with reliable measurements in both circular polarizations, we measured circular-polarization ratios greater than 1.0, which could indicate that they are E-type asteroids, while the mean and the ...
Ground-based planetary radar observations first revealed deposits of potentially nearly pure wate... more Ground-based planetary radar observations first revealed deposits of potentially nearly pure water ice in some permanently shadowed regions (PSRs) on Mercury’s poles. Later, the MESSENGER spacecraft confirmed the icy nature of the deposits, as well as their location within PSRs. Considering the geologic context provided by MESSENGER, we further characterized the north polar deposits by pairing spacecraft data with new Arecibo S-band radar observations. Here we show that some ice deposits within PSRs have a gradational pattern in their radar properties that is likely associated with differences in ice purity. Radar-bright features with a circular polarization ratio μ c > 1 can be characterized by water ice with ≳3% impurities by volume while those with μ c < 1 by ≳20% impurities. Furthermore, areas in PSRs with μ c < 1 typically surround locations of stronger radar backscatter with μ c > 1. Therefore, deposits of nearly pure water ice are likely surrounded by lower-purity...
This set of 36 FITS images of radar observations of near-Earth asteroids includes image data pres... more This set of 36 FITS images of radar observations of near-Earth asteroids includes image data presented in a publication in revision: Virkki et al. Arecibo Planetary Radar Observations of Near-Earth Asteroids: 2017 December - 2019 December<br><br>Delay-Doppler images are processed and displayed as echo-power z-score normalized values in the range (directly proportional to time delay) and Doppler frequency space. The images have not been enhanced in contrast or brightness beyond setting negative values to zero in a few cases.<br>The included near-Earth asteroids and their range (vertical) and frequency (horizontal) resolutions are:(3752) Camillo, 75 m/px, 0.061 Hz/px;(13553) Masaakikoyama, 75 m/px, 0.119 Hz/px;(66391) Moshup, 30 m/px, 0.297 Hz/px;(66347) 2001 KB67, 7.5 m/px, 0.0336 Hz/px;(68950) 2002 QF15, 7.5 m/px, 0.00938 Hz/px;(90403) 2003 YE45, 75 m/px, 0.00745 Hz/px;(141593) 2002 HK12, 7.5 m/px, 0.0373 Hz/px;(144332) 2004 DV24, 7.5 m/px, 0.0745 Hz/px;(153814) 20...
The Dual-Frequency synthetic aperture radar (DFSAR) system manifested on the Chandrayaan-2 spacec... more The Dual-Frequency synthetic aperture radar (DFSAR) system manifested on the Chandrayaan-2 spacecraft represents a significant step forward in radar exploration of solid solar system objects. It combines SAR at two wavelengths (L- and S-bands) and multiple resolutions with several polarimetric modes in one lightweight (∼ 20 kg) package. The resulting data from DFSAR support calculation of the 2×2 complex scattering matrix for each resolution cell, which enables lunar near surface characterization in terms of radar polarization properties at different wavelengths and incidence angles. In this paper, we report on the calibration and preliminary performance characterization of DFSAR data based on the analysis of a sample set of crater regions on the Moon. Our calibration analysis provided a means to compare on-orbit performance with pre-launch measurements and the results matched with the pre-launch expected values. Our initial results show that craters in both permanently shadowed reg...
Introduction: High radar reflectivity has been linked to thick water ice deposits in some Solar S... more Introduction: High radar reflectivity has been linked to thick water ice deposits in some Solar System objects such as the permanently shadowed polar regions (PSRs) of Mercury and Jovian satellites [1-3]. However, radar detection of water ice in the permanently shadowed regions near the poles of the Moon has been a topic of intense debate since several years [4-7]. Apart from the ground-based planetary radar systems, since 2008, two orbital miniature synthetic aperture radars on the Chandrayaan-1 and Lunar Reconnaissance Orbiter (LRO) missions (Mini-SAR and Mini-RF respectively) have imaged the lunar surface with the main purpose of detecting the distinctive radar polarimetric signature of ice deposits at the lunar poles. Both ground-based and orbital-based high resolution radar data showed that the anomalously high radar reflectivity observed from PSRs on the Moon is not unique to the poles, and also suggested a source other than accumulations of thick water ice deposits (e.g. [6-8...
Introduction: Basaltic volcanism was once common on the Moon and is responsible for the lunar mar... more Introduction: Basaltic volcanism was once common on the Moon and is responsible for the lunar maria that covers 17% of the lunar surface [1], mostly filling the near-side basins. Volcanic features on the Moon include domes, cones, rilles, collapsed lava tubes, depressions, and pyroclastic deposits [e.g. 2, 3]. As indicated in numerous previous analyses, many possible lunar landing sites are in volcanic regions, so it is very important to ascertain their physical properties prior to landing and in-situ sampling. The lunar volcanic domes are particularly interesting as they are shown to have a variety of geologic properties [e.g. 2, 3, 4]. Here, we utilize data sets from LRO including the Mini-RF radar, LROC, and the Diviner Lunar Radiometer, to investigate the morphology, composition, and structure of some volcanic domes and related depressions, with the goal of better characterizing the style of regional volcanism that led to the formation of these constructs. Data and Methods: We a...
Introduction: The L&S band Dual-Frequency Synthetic Aperture Radar (DFSAR) onboard Chandrayaan-2 ... more Introduction: The L&S band Dual-Frequency Synthetic Aperture Radar (DFSAR) onboard Chandrayaan-2 orbiter, is the first fully (quad) polarimetric SAR system in the lunar orbit [1]. The architecture of this radar instrument supports multiple polarimetric modes of operation. DFSAR observations contribute significantly towards understanding the origin and evolution of lunar impact craters [2]. In the present study, we exhibit some initial results obtained from DFSAR L-band Full-Polarimetric (FP) observations towards understanding physical behaviour of two different groups of impact craters. Study Area and Data Used: L-band FP SAR observations obtained at 26o incidence angle over secondary craters situated on the floor of Peary Crater (87.9oN, 35.3oE) in the lunar north polar region are analysed. This region consists of one young, fresh crater and two craters that were classified as CPR anomalous craters in previous studies [3] (Fig. 1). For comparison, CPR product derived from S-band zo...
We have conducted spectral and spatial analysis of the Compton–Belkovich Thorium Anomaly (61.1°N,... more We have conducted spectral and spatial analysis of the Compton–Belkovich Thorium Anomaly (61.1°N, 99.5°E) region on the far side of the Moon based on high-resolution data from recent lunar missions. Chandrayaan-1 Moon Mineralogy Mapper data of Compton–Belkovich volcanic complex (CBVC) reveal the existence of a strong doublet feature near 2800 nm throughout the volcanic construct, which could be attributed to the presence of water and/or hydroxyl in the studied site. Very high resolution Lunar Reconnaissance Orbiter Camera–Narrow Angle Camera mosaic of the study area shows that the strongest of the hydration features within the CBVC is primarily related with either sunlit inner flanks of small-sized fresh craters or fresh escarpments associated with the central collapse structure. Moreover, Mini-RF Synthetic Aperture Radar data from Lunar Reconnaissance Orbiter mission suggests the presence of a thick pyroclastic deposit in the volcanic complex. Our study indicates that the enhanced hydration at CBVC could possibly have originated from the episodic events of eruption and effusion involving silicic magma, which could probably be responsible for the tapping of a zoned magma body with a water-rich cap. Morphology of CBVC also confirms the presence of episodic effusive and eruptive events that probably had led to the formation of elevated topography, central collapsed feature and late eruptive domes in the study area.
Volcanic calderas are found on Earth, Mars, Venus and Io, and are rare, but unique volcanic struc... more Volcanic calderas are found on Earth, Mars, Venus and Io, and are rare, but unique volcanic structures in the Solar System. Compton-Belkovich Volcanic Complex (CBVC) (60.5°N-99.5°E) on the far side of the Moon is a unique non-mare feature due to its evolved lithology, regional tectonic setting, its location being near the north pole, far from the Procellarum KREEP Terrane (PKT) and its recent association with endogenic water. High-resolution remote sensing observations of several structural features at CBVC such as ring faults, radial faults, fractures manifested by various morphological features such as domes of varied sizes and shapes and pyroclastic ash flows characterize it to be a volcanic caldera. The loading of Humboldtianum basin with basalts and subsequent development of extensional structures outside it along with high-thorium anomaly and resulting silicic volcanism at CBVC producing central collapsed caldera could be considered as an analogy to silicic calderas on Earth formed in extensional tectonic regime even though the tectonic processes involved in these two cases are entirely different, the former being impact-related, whereas the latter involves rifting or hotspot-related activities associated with extensional plate tectonics. Presence of high-reflectance feature and its extension to the east-southeast of the topographic expression and its relation with pyroclastic dispersal have been supported by radarbased Mini-RF observations and high-resolution LROC-NAC imagery. It suggests the presence of a latestage fine pyroclastic layer within the CBVC region. The diverse volcanic features that exist at the studied site indicate a series of deformation and eruption events associated with silicic magmatism and thus, CBVC could be considered as an ash flow caldera on the Moon. Here, we present a detailed appraisal of various volcanic and structural features detected at CBVC through high-resolution optical as well as radar observations. Based on the previous and present studies, an evolutionary model of the area has been proposed and the petrological implications of silicic magmatic activity, its manifestation, evolution and association with endogenic water have been discussed.
The surface layer of the Moon preserves vital evidences of lunar impact and cratering processes d... more The surface layer of the Moon preserves vital evidences of lunar impact and cratering processes due to the absence of any Aeolian and fluvial erosion processes acting on it. By examining these evidences, which are recorded throughout the evolutionary history of the Moon, several basic aspects of lunar science can be understood, and this has direct relevance to the surfaces of other airless bodies within the solar system. In this study, rock abundance data obtained from Thermal Infrared (TIR) observations and radar Circular Polarization Ratio (CPR) data sets obtained from polarimetric SAR observations were correlated at some sample sites on the lunar surface. Preliminary results yielded qualitative and quantitative estimates for surface rock abundances. Except at distal ejecta deposits of young, bright craters a general correlation was observed between the two datasets. Mixed results were observed from the impact melt flows where the situation is complex due to the possible subsurface-volume and volume-subsurface interactions of the radar waves. But the flow features were clearly separated from the interior and ejecta regions of their parent craters in terms of CPR and rock abundances. The extent and distributions of pyroclastic deposits and dark haloed regions could not be distinctly identified at the resolution of datasets utilized. Near Gerasimovich D crater, the Diviner Radiometer has provided the first TIR observations of a newly discovered impact melt flow which was not visible in the optical imagery. This facilitated the first ever quantitative comparisons of the radar CPR and rock abundance values near such a region. Also, significant differences in spatial patterns between the radar and rock concentration data sets were observed, owing to the differences in the sensitivity of the two observations.
We analyzed the morphology of pre-caldera domes, central caldera, ash-flow features, post-caldera... more We analyzed the morphology of pre-caldera domes, central caldera, ash-flow features, post-caldera effusive and eruptive features at Compton-Belkovich Complex.
FUNCTION OF VIEWING GEOMETRY. S. S. Bhiravarasu1, E. G. Rivera-Valentín1, P. A. Taylor1, G. W. Pa... more FUNCTION OF VIEWING GEOMETRY. S. S. Bhiravarasu1, E. G. Rivera-Valentín1, P. A. Taylor1, G. W. Patterson2, C. D. Neish3, and B. J. Thomson4, 1Lunar and Planetary Institute, Universities Space Research Association, 3600 Bay Area Blvd, Houston, TX 77058 ([email protected]), 2Johns Hopkins Applied Physics Laboratory, Laurel, MD, 3Department of Earth Sciences, The University of Western Ontario, London, Ontario, 4Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, TN.
CHANDRAYAAN-2 DFSAR RADARS. G. W. Patterson1, S. S. Bhiravarasu2,3, L. M. Carter4, J. T. S. Cahil... more CHANDRAYAAN-2 DFSAR RADARS. G. W. Patterson1, S. S. Bhiravarasu2,3, L. M. Carter4, J. T. S. Cahill1, T. Chakraborty3, A. Das3, E. Heggy5, R. Kumar3, G. A. Morgan6, C. D. Neish7, C. A. Nypaver8, E. M. Palmer5, D. K. Pandey3, J. B. Plescia1, D. Putrevu3, A. M. Stickle1, P. A. Taylor2, B. J. Thomson8 and the Mini-RF and DFSAR teams, ,1Planetary Exploration Group, Johns Hopkins University Applied Physics Laboratory, Laurel, MD ([email protected]), 2Lunar and Planetary Institute, USRA, Houston, TX, 3Space Applications Centre (ISRO), Ahmedabad, Gujarat, India, 4Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, 5University of Southern California, Los Angeles, CA, 6Planetary Science Institute, Tucson, AZ, 7University of Western Ontario, London, ON, Canada, 8Dept. of Earth and Planetary Sciences, University of Tennessee, Knoxville, TN
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