BRDF of Salt Pan Regolith Samples

Laboratory Bi-directional Reflectance Distribution Function (BRDF) measurements of salt pan regolith samples are presented in this study in an effort to understand the role of spatial and spectral variability of the natural biome. The samples were obtained from Etosha Pan, Namibia (19.20 deg S, 15.93 deg E, alt. 1100 m). It is shown how the BRDF depends on the measurement geometry - incident and scatter angles and on the sample particle sizes. As a demonstration of the application of the results, airborne BRDF measurements acquires with NASA's Cloud Absorption Radiometer (CAR) over the same general site where the regolith samples were collected are compared with the laboratory results. Good agreement between laboratory measured and field measured BRDF is reported

Laboratory and Airborne BRDF Analysis of Vegetation Leaves and Soil Samples

Laboratory-based Bidirectional Reflectance Distribution Function (BRDF) analysis of vegetation leaves, soil, and leaf litter samples is presented. The leaf litter and soil samples, numbered 1 and 2, were obtained from a site located in the savanna biome of South Africa (Skukuza: 25.0degS, 31.5degE). A third soil sample, number 3, was obtained from Etosha Pan, Namibia (19.20degS, 15.93degE, alt. 1100 m). In addition, BRDF of local fresh and dry leaves from tulip tree (Liriodendron tulipifera) and acacia tree (Acacia greggii) were studied. It is shown how the BRDF depends on the incident and scatter angles, sample size (i.e. crushed versus whole leaf,) soil samples fraction size, sample status (i.e. fresh versus dry leaves), vegetation species (poplar versus acacia), and vegetation s biochemical composition. As a demonstration of the application of the results of this study, airborne BRDF measurements acquired with NASA's Cloud Absorption Radiometer (CAR) over the same general site where the soil and leaf litter samples were obtained are compared to the laboratory results. Good agreement between laboratory and airborne measured BRDF is reported

The Characterization of Earth Sediments using Radiative Transfer Models from Directional Hyperspectral Reflectance

Remote sensing techniques are continuously being developed to extract physical information about the Earth’s surface. Over the years, space-borne and airborne sensors have been used for the characterization of surface sediments. Geophysical properties of a sediment surface such as its density, grain size, surface roughness, and moisture content can influence the angular dependence of spectral signatures, specifically the Bidirectional Reflectance Distribution Function (BRDF). Models based on radiative transfer equations can relate the angular dependence of the reflectance to these geophysical variables. Extraction of these parameters can provide a better understanding of the Earth’s surface, and play a vital role in various environmental modeling processes. In this work, we focused on retrieving two of these geophysical properties of earth sediments, the bulk density and the soil moisture content (SMC), using directional hyperspectral reflectance. We proposed a modification to the radiative transfer model developed by Hapke to retrieve sediment bulk density. The model was verified under controlled experiments within a laboratory setting, followed by retrieval of the sediment density from different remote sensing platforms: airborne, space-borne and a ground-based imaging sensor. The SMC was characterized using the physics based multilayer radiative transfer model of soil reflectance or MARMIT. The MARMIT model was again validated from experiments performed in our controlled laboratory setting using several different soil samples across the United States; followed by applying the model in mapping SMC from imagery data collected by an Unmanned Aerial System (UAS) based hyperspectral sensor

Master of Science

thesisPersistent drought conditions and associated vegetation mortality in the central Sierra Nevada of California were analyzed from 2013-2015 using a combination of field-derived polygons and AVIRIS hyperspectral data. Linear Discriminant Analysis (LDA) was used to classify hyperspectral data into five land cover classes based on dominant flora. LDA accuracies were compared across years in order to determine whether classification accuracy was correlated with increasing drought severity. It was determined that 2013 had the greatest accuracy and 2015 had the lowest. However, this trend was influenced by Bidirectional Reflectance Distribution Function (BRDF) effects in the densely forested landscape. Fractional cover data of green vegetation (GV), non-photosynthetic vegetation (NPV), and soil were obtained from the US Forest Service to analyze which land cover classes and which elevation intervals experienced the greatest fractional cover change, which are both indicators of vegetation senescence and mortality. GV loss deemed the most appropriate indicator of vegetation senescence and mortality as NPV and soil appeared to be confused by the Multiple Endmember Spectral Mixture Analysis (MESMA) method used to obtain the fractional cover images. Mixed oak woodland (MO) and mixed low conifer (LC) forests experienced the greatest and second-greatest decreases in GV, respectively. Lower elevation areas (695-1369 m) generally experienced greater GV loss than higher elevation areas (2167-2779), which coincided with both MO and LC forest classes. The MO forest class, which occurs most in lower elevation areas, was comprised of dominantly drought resistant flora and experienced the greatest GV loss during the study period (16%). Conversely, the HC forest, which occurs dominantly in higher elevation areas, was comprised of dominantly non-drought-tolerant flora but experienced less GV loss (5%). This suggests that the differences in elevation and location of vegetation within the landscape played a larger role than the dominant floras' degrees of drought tolerance. Variations in seasonal senescence may have influenced the measured loss of GV for the MO and LC classes, which contained deciduous vegetation. However, overall GV loss in all classes, even those without trees, indicates that the landscape likely experienced vegetation mortality, especially at low elevations in the MO and LC classes

Signature Simulation and Characterization of Mixed Solids in the Visible and Thermal Regimes

Solid target signatures vary due to geometry, chemical composition and scene radiometry. Although radiative transfer models and function-fit physical models may describe certain targets in limited depth, the ability to incorporate all three of these signature variables is difficult. This work describes a method to simulate the transient signatures of mixed solids and soils by first considering scene geometry that was synthetically created using 3-d physics engines. Through the assignment of spectral data from the Nonconventional Exploitation Factors Data System (NEFDS) and other libraries, synthetic scenes are represented as a chemical mixture of particles. Finally, first principles radiometry is modeled using the Digital Imaging and Remote Sensing Image Generation (DIRSIG) model. With DIRSIG, radiometric and sensing conditions were systematically manipulated to produce goniometric signatures. The implementation of this virtual goniometer allows users to examine how a target bidirectional reflectance function (BRDF) and directional emissivity will change with geometry, composition and illumination direction. The tool described provides geometry flexibility that is unmatched by radiative transfer models. It delivers a discrete method to avoid the significant cost of time and treasure associated with hardware based goniometric data collections

The PanCam Instrument for the ExoMars Rover

The scientific objectives of the ExoMars rover are designed to answer several key questions in the search for life on Mars. In particular, the unique subsurface drill will address some of these, such as the possible existence and stability of subsurface organics. PanCam will establish the surface geological and morphological context for the mission, working in collaboration with other context instruments. Here, we describe the PanCam scientific objectives in geology, atmospheric science, and 3-D vision. We discuss the design of PanCam, which includes a stereo pair of Wide Angle Cameras (WACs), each of which has an 11-position filter wheel and a High Resolution Camera (HRC) for high-resolution investigations of rock texture at a distance. The cameras and electronics are housed in an optical bench that provides the mechanical interface to the rover mast and a planetary protection barrier. The electronic interface is via the PanCam Interface Unit (PIU), and power conditioning is via a DC-DC converter. PanCam also includes a calibration target mounted on the rover deck for radiometric calibration, fiducial markers for geometric calibration, and a rover inspection mirror.publishersversionPeer reviewe

The Sixth International Conference on Mars Polar Science and Exploration : September 5-9, 2016, Reykjavik, Iceland

The conference is designed to pull together the current state of Mars polar research from many fields, including geology, atmospheric, and climate sciences.European Geophysical Union Icelandic Meteorological Office International Association of Cryospheric Sciences Lunar and Planetary Institute (LPI) NASA Mars Program Office Planetary Science Institute Southwest Research Institute Université de Nantes University of Iceland in ReykjavikConference Organizing Committee, Isaac Smith, Convener, Southwest Research Institute [and 7 others] ; Science Organizing Committee, Wendy Calvin, University of Nevada [and 13 others

Lunar and Planetary Science 35

Special sessions: Oxygen in the Solar System I, Oxygen in the Solar System II, and Mars Missions, and Mars Climate Change. Includes preface, table of contents, program, abstracts and indexes for the 35th LPSC.sponsors Lunar and Planetary Institute, NASA Johnson Space CenterPARTIAL CONTENTS: A New Lunar Geologic Mapping Program / L. Gaddis, K. Tanaka, T. Hare, J. Skinner, B.R. Hawke, P. Spudis, B. Bussey, C. Pieters, and D. Lawrence--Mineralogical Variations Among High Albedo E-Type Asteroids: Implications for Asteroid Igneous Processes / M.J. Gaffey and M.S. Kelley--(26Al/27Al)o of the Solar Nebula Inferred from Al-Mg Systematic in Bulk CAIs from CV3 Chondrites / A. Galy, I.D. Hutcheon, and L. Grossman--Petrology of New Stannern-trend Eucrites and Eucrite Genesis / K.G. Gardner and D.W. Mittlefehldt--Ellipses of the South Pole-Aitken Basin: Implications for Basin Formation / I. Garrick-Bethell.program committee, Stephen J. Mackwell, co-chair, Eileen K. Stansbery, co-chair ... [and others] ; compiled by Lunar and Planetary Institute.1 CD-ROM (595 MB

Integrated Applications of Geo-Information in Environmental Monitoring

This book focuses on fundamental and applied research on geo-information technology, notably optical and radar remote sensing and algorithm improvements, and their applications in environmental monitoring. This Special Issue presents ten high-quality research papers covering up-to-date research in land cover change and desertification analyses, geo-disaster risk and damage evaluation, mining area restoration assessments, the improvement and development of algorithms, and coastal environmental monitoring and object targeting. The purpose of this Special Issue is to promote exchanges, communications and share the research outcomes of scientists worldwide and to bridge the gap between scientific research and its applications for advancing and improving society

Lunar and Planetary Science 36

Special sessions: Genesis: What We Know, Where We Stand, and the Future, and OMEGA@Mars: New Insights Into Surface Composition. Includes preface, table of contents, program, abstracts and indexes for the 36th LPSC.sponsors Lunar and Planetary Institute, NASA Johnson Space Centerprogram committee, Stephen J. Mackwell, co-chair, Eileen K. Stansbery, co-chair ... [and others] ; compiled by Lunar and Planetary Institute.PARTIAL CONTENTS: Why Small is Beautiful--and How to Detect Another 10 Billion Small Main Belt Asteroids / H. Haack, P.R. Bidstrup, R. Michelsen, A.C. Andersen, and J.L. Jørgensen -- Basalts in Mare Humorum and S.E. Procellarum / T. Hackwill, J.E. Guest, and P.D. Spudis -- Basalts in Mare Serenitatis, Lacus Somniorum, Lacus Mortis and Part of Mare Tranquillitatis / T. Hackwill, J.E. Guest, and P.D. Spudis -- Revised Thorium Abundances for Lunar Red Spots / J.J. Hagerty, D.J. Lawrence, R.C. Elphic, W.C. Feldman, D.T. Vaniman, and B.R. Hawke -- Integrating Global-Scale Mission Datasets, Understanding the Martian Crust / B.C. Hahn, S.M. McLennan, G.J. Taylor, and W.V. Boynton