Article
Environmental Sciences
Yong Yang, Xue-Song Wang
Summary: This paper proposes a radar detection method that uses a single transmitting antenna and three receiving antennas to tackle the fading problem caused by specular reflection in radar target echoes. The method employs the maximum absolute value of the difference in the radar received signal power among the three receiving antennas as the test statistic. It analyzes the target echo in the presence of specular reflection, discusses the selection of the required number of radar antennas and their heights, derives analytical expressions of the radar detection probability and the false alarm probability, and presents simulation results that demonstrate the improved radar detection performance of the proposed method in the presence of specular reflection.
Article
Astronomy & Astrophysics
A. Chatain, J. E. Wahlund, O. Shebanits, L. Z. Hadid, M. Morooka, N. J. T. Edberg, O. Guaitella, N. Carrasco
Summary: The study reanalyzed data from the Cassini mission in the ionosphere of Titan, identifying four different populations of electrons originating from different sources, including photo-ionization from the surface and atmospheric molecules.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2021)
Article
Astronomy & Astrophysics
A. Chatain, J-E Wahlund, O. Shebanits, L. Z. Hadid, M. Morooka, N. J. T. Edberg, O. Guaitella, N. Carrasco
Summary: Reanalyzing data from Titan's ionosphere, it was found that multiple electron populations are needed to fit the observed data, with the populations varying based on solar illumination and altitude. This suggests that factors such as photo-ionization, magnetospheric particles, dusty plasma, and electron emission from the probe boom contribute to the electron populations.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2021)
Article
Chemistry, Analytical
Paul A. Hwang, Thomas L. Ainsworth, Jeffrey D. Ouellette
Summary: This paper explores the application of microwave reflectometers in studying ocean surface waves. A model is developed to establish the relationship between the observed radar cross section and surface wave properties. Challenges remain in acquiring a sufficient number of high-wind reference measurements.
Article
Engineering, Electrical & Electronic
Paul Connetable, Knut Conradsen, Allan Aasbjerg Nielsen, Henning Skriver
Summary: This paper investigates the removal of speckle and the characteristics of the local covariance matrix in polarimetric synthetic aperture radar (SAR) images. Test statistics based on block-diagonality and change detection are used to detect man-made structures with high potential. The results show that the method is effective in highlighting buildings and urban areas, as well as in ship detection at longer wavelengths.
IEEE JOURNAL OF SELECTED TOPICS IN APPLIED EARTH OBSERVATIONS AND REMOTE SENSING
(2022)
Article
Computer Science, Artificial Intelligence
Casper Find Andersen, Ivar Farup, Jon Yngve Hardeberg
Summary: This paper presents a new method for estimating camera response values linearly based on a color chart. The method linearizes the responses by compensating for volumetric and per color channel non-linearities, and estimates the spatial geometry of the irradiance incident on the chart. It introduces a novel additivity principle derived from the spectral reflectances of the color chart, which is not subject to metamerism.
IEEE TRANSACTIONS ON IMAGE PROCESSING
(2023)
Article
Environmental Sciences
Liujun Zhu, Shanshui Yuan, Yi Liu, Cheng Chen, Jeffrey P. Walker
Summary: Time series algorithms for soil moisture retrieval from SAR data have gained popularity due to their feasibility and the availability of dense time series SAR data. However, how to constrain a time series retrieval for global soil moisture mapping is still unresolved. In this study, three kinds of time series constraints were developed and evaluated, providing suggestions for improving soil moisture retrieval.
REMOTE SENSING OF ENVIRONMENT
(2023)
Article
Environmental Sciences
Peng Fang, Jinhai Zhang
Summary: A recursive signal enhancement scheme is proposed to enhance the clarity of radar echoes and reveal delicate sedimentary structures buried in background noise.
Article
Engineering, Electrical & Electronic
Guo Li, Yunhua Zhang, Xiao Dong
Summary: In this article, a Ku-band geophysical model function named KuLMOD-H is proposed for wind speed retrieval using the TG2-InIRA. The model is based on the quasispecular reflection model and exploits quadratic polynomials to expand the effective nadir reflection coefficient term and the mean square slope term. The model coefficients are obtained by fitting radar backscattering coefficient data to collocated sea surface wind speed data. A regularization approach is further proposed to solve the problem of potential ambiguous solutions. The retrieved wind speed results show high consistency with buoy data and have a small root-mean-square error compared to ECMWF wind speed data. This work provides a semi-physical model suitable for low incidence-angle observation and offers high-resolution wind speed data for sea state bias correction of TG2-InIRA sea surface height measurements.
IEEE JOURNAL OF SELECTED TOPICS IN APPLIED EARTH OBSERVATIONS AND REMOTE SENSING
(2022)
Article
Computer Science, Information Systems
Hongliang Zhu
Summary: This paper proposes a novel deep marginal learning algorithm for the classification of dark areas in airborne SAR images. By using a Snake Search Algorithm to generate margin slices and training them with a deep convolutional neural network, the method achieves high classification accuracy and improves time efficiency.
Article
Environmental Sciences
Qinghua Xie, Kunyu Lai, Jinfei Wang, Juan M. Lopez-Sanchez, Jiali Shang, Chunhua Liao, Jianjun Zhu, Haiqiang Fu, Xing Peng
Summary: The study evaluates crop monitoring and classification using multitemporal PolSAR images, finding that certain polarimetric observables are more sensitive to crop growth. By utilizing the Random Forest algorithm for crop classification, the study achieves high classification accuracies by optimizing the combination of polarimetric observables and multitemporal SAR images.
Article
Geography, Physical
Yitong Luo, Xiaolan Qiu, Lingxiao Peng, Wei Wang, Bei Lin, Chibiao Ding
Summary: This paper investigates the challenges of extracting refined digital surface models using stereo SAR and proposes a novel stereo SAR approach combined with geometric semantic constraints to reduce the impact of matching errors on localization. Simulation experiments and real data experiments demonstrate the effectiveness of the proposed method.
ISPRS JOURNAL OF PHOTOGRAMMETRY AND REMOTE SENSING
(2022)
Article
Geochemistry & Geophysics
Yu Liu, James Irving, Klaus Holliger
Summary: Migration focusing analysis is an important tool for estimating large-scale subsurface velocity structure from surface-based GPR reflection data. A weighting strategy is proposed to improve the reliability of the velocity estimations using local semblance focusing measure. The weighting function, derived from coherency and slope attributes, increases the resolution of the inferred semblance spectra. The proposed method is applied to synthetic test cases and a field GPR dataset, showing increased resolution and reduced picking uncertainty compared to conventional unweighted semblance spectra.
IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING
(2023)
Article
Geochemistry & Geophysics
Qiqi Dai, Yee Hui Lee, Hai-Han Sun, Genevieve Ow, Mohamed Lokman Mohd Yusof, Abdulkadir C. Yucel
Summary: This paper proposes a 3D deep learning scheme called 3DInvNet for reconstructing 3D permittivity maps from ground-penetrating radar (GPR) data, which is important for mapping subsurface environments and inspecting underground structural integrity.
IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING
(2023)
Article
Environmental Sciences
Wei-Tao Zhang, Min Wang, Jiao Guo, Shun-Tian Lou
Summary: Accurate crop classification information is essential for agricultural monitoring and food security evaluation research. This study utilized multi-temporal PolSAR data and neural network techniques to enhance classification performance, showing promising results for practical application in agricultural monitoring and food security evaluation.
Article
Geosciences, Multidisciplinary
Ralph D. Lorenz
Summary: Saltation modeling by Comola et al. (2022) suggests smaller sand size and frequent sand transport on Titan, contradicting previous assumptions. The upcoming Dragonfly mission can test these predictions.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Multidisciplinary Sciences
S. Maurice, B. Chide, N. Murdoch, R. D. Lorenz, D. Mimoun, R. C. Wiens, A. Stott, X. Jacob, T. Bertrand, F. Montmessin, N. L. Lanza, C. Alvarez-Llamas, S. M. Angel, M. Aung, J. Balaram, O. Beyssac, A. Cousin, G. Delory, O. Forni, T. Fouchet, O. Gasnault, H. Grip, M. Hecht, J. Hoffman, J. Laserna, J. Lasue, J. Maki, J. McClean, P. -y. Meslin, S. Le Mouelic, A. Munguira, C. E. Newman, J. A. Rodriguez Manfredi, J. Moros, A. Ollila, P. Pilleri, S. Schroder, M. de la Torre Juarez, T. Tzanetos, K. M. Stack, K. Farley, K. Williford
Summary: The acoustic environment on Mars was unknown before the Perseverance rover landing. This study presents the first characterization of the acoustic environment on Mars using Perseverance microphone recordings, providing important data for atmospheric studies.
Article
Astronomy & Astrophysics
Ralph D. Lorenz
Summary: This paper presents simple discrete and continuous gust models for the lower atmosphere of Titan to verify the design of the Dragonfly rotorcraft. The existing models for terrestrial airworthiness certification, which are essentially empirical, cannot be directly applied due to the different properties of Titan's atmosphere. The origins of terrestrial specifications are reviewed, and the relevant parameters are scaled using first-principles physics. A discrete 'random-walk' turbulence formulation is introduced, providing a simple implementation for numerical flight simulations and applicability to other missions.
PLANETARY AND SPACE SCIENCE
(2022)
Article
Astronomy & Astrophysics
Ralph D. Lorenz
Summary: The strength of the surface materials on Titan is considered in order to determine the required landing gear for Dragonfly's operations. The soft and hard limits of the materials are taken into account, as well as the friction coefficient and adhesion term for takeoff.
PLANETARY AND SPACE SCIENCE
(2022)
Article
Astronomy & Astrophysics
Shea N. Thorne, Catherine L. Johnson, Anna Mittelholz, Benoit Langlais, Ralph Lorenz, Naomi Murdoch, Aymeric Spiga, Suzanne E. Smrekar, W. Bruce Banerdt
Summary: The NASA InSight lander has recorded pressure drops attributed to convective vortices. However, dust-carrying vortices have not been observed in InSight images. The study examines if magnetic signals are associated with daytime vortices and finds a small proportion of pressure drop events showing significant magnetic field signals, with no clear correlation.
PLANETARY AND SPACE SCIENCE
(2022)
Article
Astronomy & Astrophysics
Jason J. Benkoski, Timothy J. Montalbano, William L. Luedeman, John O. Teehan, Ralph D. Lorenz
Summary: The factors controlling dust particle adhesion are crucial for camera system design on the Moon, Mars, asteroids, and Titan. Previous experiments found that maximizing window surface electrical conductivity and minimizing surface energy can reduce adhesion of Titan dust simulants to camera windows. In this study, the effects of airflow velocity on dust adhesion were tested using sapphire windows coated with indium tin oxide and treated with fluorosilane. Results showed that dust adhesion was highest within a narrow range of airflow velocities centered at 0.11 m/s. The presence of large particles above 0.16 m/s prevented the adhesion of medium-sized particles, while particles larger than 200 μm were generally too heavy to adhere to the window at any velocity.
PLANETARY AND SPACE SCIENCE
(2023)
Article
Astronomy & Astrophysics
Richard H. Chen, Roger J. Michaelides, Yuhuan Zhao, Lingcao Huang, Elizabeth Wig, Taylor D. Sullivan, Andrew D. Parsekian, Howard A. Zebker, Mahta Moghaddam, Kevin M. Schaefer
Summary: Seasonal subsidence induced by ground ice melt can provide valuable information about active layer thickness (ALT) in permafrost regions. This study combined L-band InSAR subsidence and P-band PolSAR backscatter to simultaneously estimate ALT and soil moisture profile. The joint retrieval approach has been applied to SAR data acquired during the 2017 Arctic-Boreal Vulnerability Experiment, providing regional estimates of ALT and soil moisture profile for the ABoVE study domain.
EARTH AND SPACE SCIENCE
(2023)
Article
Engineering, Aerospace
Ralph D. Lorenz, Gary A. Allen Jr
Summary: This article presents previously-unpublished data from the Pioneer Venus multiprobe mission, documenting key events in the entry and descent process. The data includes the latter part of the hypersonic entry, deceleration through the transonic region, and parachute deployment. The comparison with the DAVINCI mission and other missions' parachute deployment records provides insights into the sample rate required to characterize key events.
ADVANCES IN SPACE RESEARCH
(2023)
Meeting Abstract
Acoustics
Louise L. Zhuang, Jeremy Dahl, Howard Zebker, Marko Jakovljevic
JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA
(2023)
Article
Astronomy & Astrophysics
Ralph D. Lorenz, Sylvestre Maurice, Baptiste Chide, David Mimoun, Alexander Stott, Naomi Murdoch, Martin Giller, Xavier Jacob, Roger C. Wiens, Franck Montmessin, Havard Grip, Theodore Tzanetos, Bob Balaram, Nathan Williams, Matt Keennon, Sara Langberg, Jeremy Tyler, Tanguy Bertrand, Adrian Brown, Nicolas Randazzo, Benjamin Pipenberg
Summary: The sounds of the Ingenuity Helicopter flying in the Martian atmosphere were recorded by the microphone on the SuperCam instrument. The recorded audio signals show distinct frequencies at 84 Hz and occasionally at 168 Hz, corresponding to the blade crossing frequency and its first harmonic. The sound recordings also exhibit a deep modulation with nulls spaced by around 15-20s, in addition to the expected decline in amplitude with distance.
PLANETARY AND SPACE SCIENCE
(2023)
Article
Geochemistry & Geophysics
Alexander E. Stott, Naomi Murdoch, Martin Gillier, Don Banfield, Tanguy Bertrand, Baptiste Chide, Manuel De la Torre Juarez, Ricardo Hueso, Ralph Lorenz, German Martinez, Asier Munguira, Luis Mora Sotomayor, Sara Navarro, Claire Newman, Paolo Pilleri, Jorge Pla-Garcia, Jose Antonio Rodriguez-Manfredi, Agustin Sanchez-Lavega, Michael Smith, Daniel Viudez Moreiras, Nathan Williams, Sylvestre Maurice, Roger C. Wiens, David Mimoun
Summary: We use SuperCam's Mars microphone to provide information on high-frequency wind speed and turbulence on Mars. We demonstrate the sensitivity of the microphone signal level to wind speed and establish a power law dependence. A calibration function is developed using Gaussian process regression, which takes the microphone signal and air temperature as inputs to estimate the wind speed. This enables us to analyze the fast fluctuations and turbulent behavior of the wind on Mars.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2023)
Article
Astronomy & Astrophysics
Ralph Lorenz
Summary: This paper reviews topographic slopes on Titan. Cassini radar provides information on large scale slopes, while Arecibo and Cassini radar scattering properties provide information on wavelength scale slopes. The slopes on Titan are shallower compared to terrestrial planets and the Moon. The overall slope statistics suggest a fractal Hurst exponent of -0.5, but deviations may exist at dune and gravel scales. The design requirements for the Dragonfly lander and other missions are contextualized by comparing the slope tolerance of previous planetary lander missions with terrestrial rotorcraft specifications.
PLANETARY AND SPACE SCIENCE
(2023)
Article
Geochemistry & Geophysics
Keisuke Onodera, Kiwamu Nishida, Taichi Kawamura, Naomi Murdoch, Melanie Drilleau, Ryoji Otsuka, Ralph Lorenz, Anna Horleston, Rudolf Widmer-Schnidrig, Martin Schimmel, Sebastien Rodriguez, Sebastian Carrasco, Satoshi Tanaka, Clement Perrin, Philippe Lognonne, Aymeric Spiga, Don Banfield, Mark Panning, William Bruce Banerdt
Summary: Convective vortices and dust devils are common phenomena on Mars that reflect the atmospheric structure and drive the dust cycle. Investigating these vortices can improve our understanding of the Martian atmosphere and subsurface properties. NASA's InSight was used to study the vortices with meteorological and seismic data, resulting in a catalog of parameters to characterize their structure and subsurface properties. The study found that most vortices move with a tilted wall in the advection direction and that the subsurface structure can be modeled with two layers transitioning at depths of 5-15 meters.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2023)
Editorial Material
Geochemistry & Geophysics
Ralph D. Lorenz
Summary: Observations using sensitive photodiode detectors, along with movie recordings of the Ingenuity helicopter's downwash impingement, provide new insights into the dust-lifting phenomenon on Mars, revealing that particle motion and darkening can be caused by lower aerodynamic pressures than previously thought.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2023)
Article
Astronomy & Astrophysics
Aadvik S. Vashist, Michael F. Heslar, Jason W. Barnes, Corbin Hennen, Ralph D. Lorenz
Summary: We document the evolution of the north-south asymmetry (NSA) of Titan's haze albedo during the Cassini mission. Over half of a Titan year, we observe a near-complete transition in the NSA boundary latitude across the geographic equator from the southern to the northern hemisphere. Comparison of NSA images taken at similar times but different phase angles shows the NSA boundary is detectable, albeit with less contrast, at moderately high phase angles.
PLANETARY SCIENCE JOURNAL
(2023)