6-meter wavelength polarimetric inverse synthetic aperture radar mapping of the Moon

Remote sensing of planetary surfaces is an effective method for gaining knowledge of the processes that shape the planetary bodies in our solar system. This is useful for uncovering the environment of the primordial solar system and to study the current state of the upper crusts of the other planets in our neighborhood. A recent 6-meter wavelength polarimetric radar map of the Moon showed unexpectedly low depolarized radar returns in two regions on the lunar nearside. These two areas were a highland region between Mare Imbrium and Mare Frigoris, and the highland area surrounding the Schiller-Zucchius impact basin. These two regions showed characteristics unlike those of typical highland regions of the lunar surface. So far, there has been no readily available explanation for this observation. In this study, it is shown that the likely cause is an increased loss tangent due to chemical differences in the first few hundred meters of the lunar soil. We also show the absence of any coherent subsurface, which could be the preserved remains of an ancient basaltic plain. We do this by comparing the 6-meter polarimetric radar map to other relevant data sets: 1) surface TiO_2 and FeO abundance, 2) surface rock population, 3) radar maps of the Moon with other wavelengths, and 4) visual spectrum images of the Moon. The area near the Schiller-Zucchius basin was shown to be consistent with other areas with similar surface chemical compositions, but the region between Mare Imbrium and Mare Frigoris showed significantly lower mean power in comparison to otherwise similar regions. While we can not conclusively determine the cause, we hypothesize that the low radar return is explained by an increased concentration of iron and titanium oxides in the volume beneath the surface, potentially due to remnants of primordial lunar volcanism. The results show that long wavelength polarimetric radar measurements of the Moon are very powerful tools for studying the earliest stages of the evolution of the Moon

PERISCOPE: PERIapsis Subsurface Cave Optical Explorer

The PERISCOPE study focuses primarily on lunar caves, due to the potential for being imaged in orbital scenarios. In the intervening years, from 2012-2015, scientists developed further rationales and interest in the scientific value of lunar caves. It does not appear that they are likely to be sinks for water-ice due to the relatively warm temperatures(~-20 degrees Celsius) in the caves leading to geologically-rapid migration of unbound water due to sublimation, and inevitable loss through any skylights. However, the skylights themselves reveal apparent complex layering, which may speak to a more complex multi-stage evolution of mare flood basalts than previously considered, and so their examination may provide even more insight into the lunar mare, which in turn provide a primary record of early solar system crustal formal and evolution processes. Further extrapolation of these insights can be found within the exoplanet community of researchers,who find the information useful for calibrating star formation and planetary evolution models. In addition, catalogues of lunar and martian skylights, "caves" or "atypical pit craters" have been developed, with numbers for both bodies now in the low hundreds thanks to additional high resolution surveys and revisiting the existing image databases

Radar sounding using the Cassini altimeter waveform modeling and Monte Carlo approach for data inversion observations of Titan's seas

Recently, the Cassini RADAR has been used as a sounder to probe the depth and constrain the composition of hydrocarbon seas on Saturn's largest moon, Titan. Altimetry waveforms from observations over the seas are generally composed of two main reflections: the first from the surface of the liquid and the second from the seafloor. The time interval between these two peaks is a measure of sea depth, and the attenuation from the propagation through the liquid is a measure of the dielectric properties, which is a sensitive property of liquid composition. Radar measurements are affected by uncertainties that can include saturation effects, possible receiver distortion, and processing artifacts, in addition to thermal noise and speckle. To rigorously treat these problems, we simulate the Ku-band altimetry echo received from Titan's seas using a two-layer model, where the surface is represented by a specular reflection and the seafloor is modeled using a facet-based synthetic surface. The simulation accounts for the thermal noise, speckle, analog-to-digital conversion, and block adaptive quantization and allows for possible receiver saturation. We use a Monte Carlo method to compare simulated and observed waveforms and retrieve the probability distributions of depth, surface/subsurface intensity ratio, and subsurface roughness for the individual double-peaked waveform of Ligeia Mare acquired by the Cassini spacecraft in May 2013. This new analysis provides an update to the Ku-band attenuation and results in a new estimate for its loss tangent and composition. We also demonstrate the ability to retrieve bathymetric information from saturated altimetry echoes acquired over Ontario Lacus in December 2008

Radar Imaging in Challenging Scenarios from Smart and Flexible Platforms

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Annual meeting of the Lunar Exploration Analysis Group : October 22–24, 2012, Greenbelt, Maryland

The focus of this meeting will be a discussion of the ongoing contributions of the Apollo program to solar system exploration and options and opportunities for the next decade of lunar science and exploration. This meeting will include presentations and discussions on science objectives, robotic and human exploration strategies and technologies, critical required technology development commercial opportunities, education and outreach, and the Moon as a necessary stepping stone to the rest of the solar system.Sponsor: National Aeronautics and Space AdministrationConveners: Charles Shearer, University of New Mexico, Jeffrey Plescia, The John Hopkins Applied Physics Laboratory, Clive Neal, University of Notre Dame, Stephen Mackwell, Lunar and Planetary Institute.PARTIAL CONTENTS: Volatile Extraction and In Situ Resource Utilization for the Moon Applied to Near Earth Objects / E. H. Cardiff--A Revisit to Apollo Magnetic Field Records for Sounding of the Lunar Interior / P. J. Chi--LunarCube: Payload Development for Enhanced Yet Low Cost Lunar Exploration / P. E. Clark, R. MacDowall, R. Cox, A. Vasant, S. Schaire, and B. Malphrus--Frontier: Towards Onboard Intelligence for More Capable Next Generation Space Assets / P. E. Clark, M. L. Rilee, and S. A. Curtis--Near Real-Time Prospecting for Lunar Volatiles: Demonstrating RESOLVE Science in the Field / A. Colaprete, R. Elphic, J. Heldmann, K. Ennico, G. Mattes, and J. Sanders--Gateways to the Solar System: Innovative Advanced Magnet Lab Mass Driver Launch Platforms at L1 and L--R. Cox, P. Clark, A. Vasant, and R. Meinke--Modal Evaluation of Fluid Volume in Spacecraft Propellant Tanks / K. M. Crosby, R. Werlink, S. Mathe, and K. Lubick--Ground Data Systems for Real Time Lunar Science / M. C. Deans, T. Smith, D. S. Lees, E. B. Scharff, T. E. Cohen, and D. S. S. Lim

A Multi-Wavelength Remote Sensing Investigation of Lunar Surface and Crustal Evolution

The surface of Earth\u27s Moon is a complex geologic system that continues to evolve due to a variety of ongoing geologic processes. The goal of this dissertation is to identify and quantify current endogenic and exogenic sources of lunar surface modification using remote sensing data. Radar and thermophysical measurements of 6,221 impact craters on the lunar nearside mare have indicated that lunar regolith is highly mobile at crater rims, making those areas ideal locations for lunar sampling initiatives (Chapter 1). Furthermore, a detailed mapping of recently formed tectonic features on the Moon revealed \u3e1000 wrinkle ridges that are recently or currently active in deforming the lunar surface (Chapter 2). That addition of small-scale wrinkle ridges to the lithospheric stress budget of the Moon allowed for the first globally complete perspective of recent lunar tectonism. Lastly, drone-based thermophysical data collected over the ejecta of Barringer Meteorite Impact crater in NE Arizona, USA indicated that coarse-resolution measurements of impact ejecta on the Moon may be excluding key details about impact crater and ejecta formation processes (Chapter 3). The combination of these investigations indicated that Earth’s Moon is recently (if not, currently) active and the resulting surface acceleration is likely responsible for regional regolith movement in high-sloping areas of the lunar surface, such as crater rims where subsurface boulders are actively being exhumed. These findings are relevant to future lunar surface science investigations for which a lithologically diverse sampling of locally sourced lunar surface material is desired

Elevation and Deformation Extraction from TomoSAR

3D SAR tomography (TomoSAR) and 4D SAR differential tomography (Diff-TomoSAR) exploit multi-baseline SAR data stacks to provide an essential innovation of SAR Interferometry for many applications, sensing complex scenes with multiple scatterers mapped into the same SAR pixel cell. However, these are still influenced by DEM uncertainty, temporal decorrelation, orbital, tropospheric and ionospheric phase distortion and height blurring. In this thesis, these techniques are explored. As part of this exploration, the systematic procedures for DEM generation, DEM quality assessment, DEM quality improvement and DEM applications are first studied. Besides, this thesis focuses on the whole cycle of systematic methods for 3D & 4D TomoSAR imaging for height and deformation retrieval, from the problem formation phase, through the development of methods to testing on real SAR data. After DEM generation introduction from spaceborne bistatic InSAR (TanDEM-X) and airborne photogrammetry (Bluesky), a new DEM co-registration method with line feature validation (river network line, ridgeline, valley line, crater boundary feature and so on) is developed and demonstrated to assist the study of a wide area DEM data quality. This DEM co-registration method aligns two DEMs irrespective of the linear distortion model, which improves the quality of DEM vertical comparison accuracy significantly and is suitable and helpful for DEM quality assessment. A systematic TomoSAR algorithm and method have been established, tested, analysed and demonstrated for various applications (urban buildings, bridges, dams) to achieve better 3D & 4D tomographic SAR imaging results. These include applying Cosmo-Skymed X band single-polarisation data over the Zipingpu dam, Dujiangyan, Sichuan, China, to map topography; and using ALOS L band data in the San Francisco Bay region to map urban building and bridge. A new ionospheric correction method based on the tile method employing IGS TEC data, a split-spectrum and an ionospheric model via least squares are developed to correct ionospheric distortion to improve the accuracy of 3D & 4D tomographic SAR imaging. Meanwhile, a pixel by pixel orbit baseline estimation method is developed to address the research gaps of baseline estimation for 3D & 4D spaceborne SAR tomography imaging. Moreover, a SAR tomography imaging algorithm and a differential tomography four-dimensional SAR imaging algorithm based on compressive sensing, SAR interferometry phase (InSAR) calibration reference to DEM with DEM error correction, a new phase error calibration and compensation algorithm, based on PS, SVD, PGA, weighted least squares and minimum entropy, are developed to obtain accurate 3D & 4D tomographic SAR imaging results. The new baseline estimation method and consequent TomoSAR processing results showed that an accurate baseline estimation is essential to build up the TomoSAR model. After baseline estimation, phase calibration experiments (via FFT and Capon method) indicate that a phase calibration step is indispensable for TomoSAR imaging, which eventually influences the inversion results. A super-resolution reconstruction CS based study demonstrates X band data with the CS method does not fit for forest reconstruction but works for reconstruction of large civil engineering structures such as dams and urban buildings. Meanwhile, the L band data with FFT, Capon and the CS method are shown to work for the reconstruction of large manmade structures (such as bridges) and urban buildings

Lunar Reconnaissance Orbiter Science Targeting Meeting : Arizona State University, Tempe, Arizona, June 9-11, 2009

A key goal of this meeting was to foster understanding of LRO capabilities and the mission planning processes necessary for high-resolution targeting of lunar features by the LRO Narrow Angle Cameras (NAC), Mini-RF synthetic aperture radar, and Diviner Lunar Radiometer Experiment. Another goal was to solicit ideas from the lunar science community for LRO targeting of specific types of features and focused science themes.conveners : Steve Mackwell ... [and others] ; organizing committee: Mark Robinson ... [and others]The Lunar Regolith as a Remote Sensing Target for the Lunar Reconnaissance Orbiter (LRO)--Lunar Volcanism: Timing, Form, and Composition--Lunar Crustal Rock Types, Global Distribution, and Targeting--Lunar Resources and LRO--Targeting Complex Craters and Multi-Ring Basins to Determine the Tempo of Impact Bombardment While Simultaneously Probing the Lunar Interior--Current Understanding of Lunar Volatile Transport and Segregation

Fortieth Lunar and Planetary Science Conference

Special sessions on Lunar Missions, Messenger at Mercury, and Icy Satellites of Jupiter and Saturn were held. This CD-ROM contains the contents, program, abstracts, and author indexes for the 40th Lunar and Planetary Science Conference.sponsored by Lunar and Planetary Institute, NASA Johnson Space Centerconference co-chairs, Stephen J. Mackwell, Eileen StansberyPARTIAL CONTENTS: Equilibrated Aggregates in Cometary IDPs: Insights into the Crystallization Process in Protoplanetary Disks / L.P. Keller and S. Messenger--The Impact Crater Jebel Waqf as Suwwan in Jordan: Effects of Target Heterogeneity and Impact Obliquity on Central Uplift Formation / T. Kenkmann, W.U. Reimold, M. Khirfan, E. Salameh, K. Konsul, T. Lehmann, and H. Khoury--The Dispersal of Pyroclasts from Apollinaris Patera, Mars / L. Kerber, J.W. Head, J.B. Madeleine, F. Forget, and L. Wilson--The Age of the Medusae Fossae Formation: Reassessment Using Lava Flow Cast and Mold Contacts / L. Kerber and J.W. Head III--Possible Liquid-like Water Produced Seepage Features on Mars / A. Kereszturi, A. Horváth, A. Sik, A. Kuti, Sz. Bérczi, T. Gánti, T. Pócs, and E. Szathmáry