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At least 289 records · Page 16
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NASA NTRS2003

Thermal Emission Spectra of Silica-coated Basalt and Considerations for Martian Surface Mineralogy

Among the most important discoveries made during the Mars Global Surveyor (MGS) mission was that the rocky materials of Mars are broadly divisible into two distinct rock types. The geological significance of this finding is dependent on the mineralogy of these rock types as well as their geographic and stratigraphic positions. Much work has yet to be done to understand these relationships and the small-scale variability of these units. For now, it is worth considering various scenarios that could have resulted in Mars global-scale mineralogical dichotomy. Such work will make clearer what must be looked for in Thermal Emission Spectrometer (TES) and Thermal Imaging Spectrometer (THEMIS) data, what to test with other data sets, and what geological processes can be considered or ruled out as we advance with interpreting Martian geologic history. Here, we suggest that exogenic coatings of secondary silica on basaltic rocks may provide a plausible explanation for the newly discovered distribution of rock types.

Kraft, M. D.↗
NASA NTRS2003

Estimating the k2 Tidal Gravity Love Number of Mars

Analysis of the orbits of spacecraft can be used to infer global tidal parameters. For Mars, the Mars Global Surveyor (MGS) spacecraft has been used to estimate the second degree Love number, k2 from the tracking DSN tracking Doppler and range data by several authors. Unfortunately, neither of the spacecraft presently in orbit are ideally suited to tidal recovery because they are in sun-synchronous orbits that vary only slightly in local time; and, further, the sub-solar location only varies by about 25 degrees in latitude. Never-the less respectable estimates of the k2 tide have been made by several authors. We present an updated solution of the degree 2 zonal Love number, compare with previous dues, and analyze the sensitivity of the solution to orbital parameters, spacecraft maneuvers, and solution methodology. Estimating the k2 Tidal Gravity Love Number of Mars.

Smith, David E.↗
NASA NTRS2004

Comparison of Plains Volcanism in the Tempe Terra Region of Mars to the Eastern Snake River Plains, Idaho with Implications for Geochemical Constraints

The Eastern Snake River Plains (ESRP) in Idaho have long been considered a terrestrial analog for the plains volcanism like that evident in Syria Planum and Tempe Terra, Mars. Both the ESRP and Tempe Terra are sediment-blanketed volcanic fields in areas with significant extensional faulting. Similar volcanic features can be observed throughout both study areas using field analysis and DEMs of the ESRP and the Mars Global Surveyor (MGS) data from Mars. These features include flow fields, low shields, shields with steep summits, and fissure eruptions. A few other volcanic features, such as cinder cones, which suggest variable compositions, volatile interactions, and multiple volcanic events can be seen in both areas. The eruptions in both the ESRP and Tempe Terra generally originate from the fissures creating elongate, multi-vent shields as well as isolated or aligned single vent shields. Many of these show evidence of radial flow patterns from summit craters as well as lava tube fed flows. The volcanoes of Tempe Terra display some of the global latitudinal parameter trends of small volcanoes on Mars. Some of these trends may be explained by the variation of volatile content and compositional variation across Mars. However, within Tempe Terra no significant local latitudinal trends can be seen in edifice attributes and not all variations are explained by global trends. This study builds upon previous studies of the Tempe Terra region and the ESRP in order to develop a more detailed representation of features and topographic data. Using these data we attempt to help constrain the composition and eruptive style of the Tempe Terra volcanoes by correlating them with the similar and quantified ESRP variations.

Weren, S. L.↗
NASA NTRS2004

Lunar and Planetary Science XXXV: Mars All Over: Geologic Mapping

The titles presented in this session include: 1) 'Geology of Noachian Martian Highlands Surrounding the Gusev Crater'; 2) 'The History of Deposition and Nature of Material in Hellas Basin, Mars'; 3) 'Geologic Mapping of the Medusae Fossae Formation on Mars'; 4) 'Geology of the Aram Chaos from MGS-Mars Odyssey Missions and Mars Express HRSC Data'; 5) 'Toward a Comprehensive Stratigraphic Column of Mars'; 6 'The Olympus Mons Aureole Deposits: Constraints on Emplacement Scenarios Based on Remotely Sensed Data'.

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NASA NTRS2004

Mapping Rock and Soil Units in the MPF IMP SuperPan Using a Kohonen Self Organizing Map

The 1997 Mars Pathfinder mission provided information on a site in the Ares Vallis floodplain. Initial analysis of multispectral data from the Imager for Mars Pathfinder (IMP) indicated the presence of only a single rock type, the 'gray rock' spectral class and various coated variants thereof (e.g., 'maroon rock'). Continued analysis of the IMP 'SuperPan' mosaic has confirmed multiple examples of a second 'black rock' spectral class existing as small cobbles in the near field and as boulders in the far field. These results are consistent with recent analysis of MGS Thermal Emission Spectrometer (TES) data which indicates that there is likely a mix of both 'Surface Type 1' (ST1) and 'Surface Type 2' (ST2) spectral classes at the MPF landing site. Nominally, the black rock spectral class would correspond to ST1 (basalts) and 'gray rock' would correspond to ST2 (andesites). Orbital remote sensing has also revealed the pervasive presence of layering on Mars. Recently it was suggested that there are extensive outcrops of the black rock spectral class in the SuperPan far field on the flanks of the Twin Peaks and on the rim of Big Crater. These authors suggested that these exposures represented outcrops of black rock from beneath a surficial, flood deposited layer. In this work, we have reexamined the MPF IMP SuperPan mosaic using an artificial neural network self organizing map (SOM) processing architecture in order to classify the distribution of spectral classes within the SuperPan. In this paper, we present initial results from that work and draw specific attention to a subset of the identified spectral classes in order to address questions relating to whether there are extensive exposures of black rock in the IMP far field, what other materials might be exposed in the far field, and what evidence there is for subsurface layering at the MPF landing site.

Farrand, W.↗
NASA NTRS2004

High-Resolution Topomapping of Mars: Life After MER Site Selection

In this abstract we describe our ongoing use of high-resolution images from the Mars Global Surveyor Mars Orbiter Camera Narrow-Angle subsystem (MGS MOC-NA) to derive quantitative topographic and slope data for the martian surface at 3 - 10-m resolution. Our efforts over the past several years focused on assessment of candidate landing sites for the Mars Exploration Rovers (MER) and culminated in the selection of sites in Gusev crater and Meridiani Planum as safe as well as scientifically compelling. As of this writing, MER-A (Spirit) has landed safely in Gusev and we are performing a limited amount of additional mapping near the landing point to support localization of the lander and rover operations planning. The primary focus of our work, however, has been extending our techniques to sample a variety of geologic terrains planetwide to support both a variety of geoscientific studies and planning and data analysis for missions such as Mars Express, Mars Reconnaissance Orbiter, and Phoenix.

Kirk, R. L.↗
NASA NTRS2004

A First Look at the Mineralogy and Geochemistry of the MER-B Landing Site in Meridiani Planum

The second MER rover (Opportunity) landed on Meridiani Planum on January 24, 2004 inside a shallow crater. The science rational for the selection of the landing site centered on detection of the mineral hematite from martian orbit by the Mars Global Surveyor Thermal Emission Spectrometer (MGS-TES) [1,2]. Other smaller occurrences of hematite are in Aram Chaos and several isolated spots in Valles Marineris. Proposed formation pathways for martian hematite include both aqueous (e.g., low temperature precipitation of Fe oxides/oxyhydroxides in a lacustrine environment, laterite-style weathering, and precipitation from fluids having a hydrothermal origin) and dry (e.g., oxidation of magnetite rich ash) processes [e.g., 1,2,3]. The crystallographic c-face of martian hematite must be exaggerated to account for the thermal emissions spectra and it must be gray in color so as to account for the absence of the characteristic spectral signature of red hematite at visible wavelengths

Morris, Richard V.↗
NASA NTRS2004

Lunar and Planetary Science XXXV: Mars Polar Processes: Land and Sky

The titles in this section include: 1) Morphological Evidence for the Large-scale Evolution of Martian North Polar Troughs? 2) New Views of the Martian Polar Regions: The Latest Results from the Mars Odyssey THEMIS Investigation; 3) Observations at the Chasma Australe Re-Entrant, South Polar Region, Mars; 4) Stratigraphic Details of Uppermost Units within South Polar Layered Deposits on Mars; 5) Detailed Geologic Analysis of Part of the South Polar Layered Deposits, Planum Australe, Mars: Part II; 6) SHARAD: Radar Volume Scattering and the Polar Layered Terrains on Mars; 7) Arabia and Memnonia Equatorial Regions with High Content of Water: Data from HEND/Odyssey; 8) Alaskan Permafrost Analogs of Martian Small Valley Networks, Thermokarst, Terrain Softening, Terraces, and Volcanic Craters; 9) Periglacial Processes in the Southern Hemisphere of Mars; 10) Thermal Modeling of Possible Surface Water Ice Deposits in Juventae Chasma; 11) Modeling Depth to Ground Ice on Mars; 12) Ground Ice at the Phoenix Landing Site: A Preflight Assessment; 13) Possible Temperature-related Differences in Slope Angle between the North and South Walls of Coprates Chasma, Mars; 14) Seasonal Variations within Korolev Crater, Mars; 15) South Polar Ar Enhancement as a Tracer for Southern Winter Horizontal Meridional Mixing; 16) An Investigation of the Correlation of Water-Ice and Dust Retrievals via the MGS TES Data Set; 17) Observations of Plasma Waves near Mars and Their Implications for Atmospheric Loss.

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NASA NTRS2004

An Extraordinary Magnetic Field Map of Mars

The Mars Global Surveyor spacecraft has completed two Mars years in nearly circular polar orbit at a nominal altitude of 400 km. The Mars crust is at least an order of magnitude more intensely magnetized than that of the Earth [1], and intriguing in both its global distribution and geometric properties [2,3]. Measurements of the vector magnetic field have been used to map the magnetic field of crustal origin to high accuracy [4]. We present here a new map of the magnetic field with an order of magnitude increased sensitivity to crustal magnetization. The map is assembled from > 2 full years of MGS night-side observations, and uses along-track filtering to greatly reduce noise due to external field variations.

Connerney, J. E. P.↗
NASA NTRS2004

Mapping Weak Crustal Magnetic Fields on Mars with Electron Reflectometry

One of the great surprises of the Mars Global Surveyor (MGS) mission was the discovery of intensely magnetized crust. These magnetic sources are at least ten times stronger than their terrestrial counterparts, probably requiring large volumes of coherently magnetized material, very strong remanence, or both. Perhaps the most intriguing aspect of these fields is their large scale coherence and organization into east-west stripes thousands of kilometers long. The anomalies were almost certainly created by thermoremanent magnetization (TRM) in the presence of a strong Martian dynamo. With few exceptions, the crustal fields are associated with the oldest terrain on Mars. Much of the northern lowlands appears to be non-magnetic, except for the relatively weak north polar anomalies and a few sources adja-cent to the dichotomy boundary, which appear to be associated with strongly magnetized crust south of the boundary. There is clear evidence for impact demagnetization of the Hellas, Argyre, and Isidis basins. Thus, Mars' crustal magnetic fields are among the oldest preserved geologic features on the planet.

Mitchell, D. L.↗
NASA NTRS2004

Lunar and Planetary Science XXXV: Mars Mineralogy: Weathered and Dry

The session "Mars Mineralogy: Weathered and Dry" presented the following reports:Hyperspectral and Field Mapping of an Archaean Komatiite Unit in the Pilbara Craton, Western Australia: Applications for CRISM Mission; Emission Spectroscopy of Smectites: Implications for the TES Andesite-weathered Basalt Debate; Volcanism and/or Aqueous Alteration on Mars: Constraints on Distinguishing Glass and Phyllosilicate in the Thermal Infrared; Olivine Weathering on Mars: Getting Back to Basics; Sulfate-cemented Soils Detected in TES Data Through the Application of an Automated Band Detection Algorithm; Thermal Emission Spectroscopy of Sulfates: Possible Hydrous Iron-Sulfate in the Soil at the MER-A Gusev Crater Landing Site ; Barite and Celestine Detection in the Thermal Infrared: Possible Application to Determination of Aqueous Environments on Mars; Search for Evaporite Minerals in Flaugergues Basin, Mars; Contributions from Hydrated States of MgSO4 to the Reservoir of Hydrogen at Equatorial Latitudes on Mars; Identification of a Quartz and Na-Feldspar Surface Mineralogy in Syrtis Major; Pigeonite Masquerading as Olivine at Mars: First Results from Mars Spectroscopy Consortium; Green Mars: Geologic Characteristics of Olivine-bearing Terrains as Observed by THEMIS, MOC, and MOLA; and Global Chemical Abundances and Distributions on Mars from MGS-TES Spectra.

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NASA NTRS2004

Analyses of IR-Stealthy and Coated Surface Materials: A Comparison of LIBS and Reflectance Spectra and Their Application to Mars Surface Exploration

Identification of non-silicate samples on Mars, such as carbonates, sulfates, nitrates, or evaporites in general, is important because of their association with aqueous processes and their potential as exobiology sites. Infrared (IR) and thermal emission (TE) spectroscopy have been considered the primary tools for remote identification of these minerals. This includes current and future orbital assets such as TES on MGS, THEMIS on Mars Odyssey, OMEGA on Mars Express, CRISM on MRO, and now the Mini-TES on the MER rovers. While reflectance and emission spectroscopy have clearly been the method of choice for these missions, the technique is not always successful in mineral identifications due to dust, surface weathering chemistry, coatings, or surface texture. Here we describe and show IR spectra of several such samples, and then report on the relative success of LIBS analyses in determining the rock type.

Wiens, R. C.↗
NASA NTRS2004

Refinement of Phobos Ephemeris Using Mars Orbiter Laser Altimeter Radiometry

Radiometric observations from the Mars Orbiter Laser Altimeter (MOLA) can be used to improve the ephemeris of Phobos, with particular interest in refining estimates of the secular acceleration due to tidal dissipation within Mars. We have searched the Mars Orbiter Laser Altimeter (MOLA) radiometry data for shadows cast by the moon Phobos, finding 7 such profiles during the Mapping and Extended Mission phases, and 5 during the last two years of radiometry operations. Preliminary data suggest that the motion of Phobos has advanced by one or more seconds beyond that predicted by the current ephemerides, and the advance has increased over the 5 years of Mars Global Surveyor (MGS) operations.

Neumann, G. A.↗
NASA NTRS2004

Lunar and Planetary Science XXXV: Mars

The session "Mars" included the following reports:Tentative Theories for the Long-Term Geological and Hydrological Evolution of Mars; Stratigraphy of Special Layers Transient Ones on Permeable Ones: Examples from Earth and Mars; Spatial Analysis of Rootless Cone Groups on Iceland and Mars; Summer Season Variability of the North Residual Cap of Mars from MGS-TES; Spectral and Geochemical Characteristics of Lake Superior Type Banded Iron Formation: Analog to the Martian Hematite Outcrops; Martian Wave Structures and Their Relation to Mars; Shape, Highland-Lowland Chemical Dichotomy and Undulating Atmosphere Causing Serious Problems to Landing Spacecrafts; Shear Deformation in the Graben Systems of Sirenum Fosssae, Mars: Preliminary Results; Components of Martian Dust Finding on Terrestrial Sedimentary Deposits with Use of Infrared Spectra; Morphologic and Morphometric Analyses of Fluvial Systems in the Southern Highlands of Mars; Light Pattern and Intensity Analysis of Gray Spots Surrounding Polar Dunes on Mars; The Volume of Possible Ancient Oceanic Basins in the Northern Plains of Mars MARSES: Possibilities of Long-Term Monitoring Spatial and Temporal Variations and Changes of Subsurface Geoelectrical Section on the Base; Results of the Geophysical Survey Salt/Water Interface and Groundwater Mapping on the Marina Di Ragusa, Sicily and Shalter Island, USA ;A Miniature UV-VIS Spectrometer for the Surface of Mars; Automatic Recognition of Aeolian Ripples on Mars; Absolute Dune Ages and Implications for the Time of Formation of Gullies in Nirgal Vallis, Mars; Diurnal Dust Devil Behaviour for the Viking 1 Landing Site: Sols 1 to 30; Topography Based Surface Age Computations for Mars: A Step Toward the Formal Proof of Martian Ocean Recession, Timing and Probability; Gravitational Effects of Flooding and Filling of Impact Basins on Mars; Viking 2 Landing Site in MGS/MOC Images South Polar Residual Cap of Mars: Features, Stratigraphy, and Changes.

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NASA NTRS2003

Observations of the Seasonal Polar Icecaps of Mars at 1064 nm

The Mars Orbiter Laser Altimeter (MOLA) is routinely making radiometric observations of Mars at a wavelength of 1064 nm. Although the altimeter function is no longer operational, the MOLA detector continues to measure the reflectivity of the surface. Observations have been obtained almost continuously since the beginning of the Mars Global Surveyor (MGS) mapping mission in February 1999, and are providing measurements relevant to understanding the seasonal cycling of CO2 surface frost.

Zuber, Maria T.↗
NASA NTRS2003

Effects of Atmospheric and Surface Dust on the Sublimation Rates of CO2 on Mars

We present an overview of our modeling work dedicated to study the effects of atmospheric dust on the sublimation of CO2 on Mars. The purpose of this study is to better understand the extent to which dust storm activity can be a root cause for interannual variability in the planetary CO2 seasonal cycle, through modifying the springtime regression rates of the south polar cap. We obtain calculations of the sublimation fluxes for various types of polar surfaces and different amounts of atmospheric dust. These calculations have been compared qualitatively with the regression patterns observed by Mars Global Surveyor (MGS) in both visible and infrared wavelengths, for two years of very different dust histories (1999, and 2001).

Bonev, B. P.↗
NASA NTRS2003

The Most Recent Section of the South Polar Layered Deposits

The polar layered deposits of both hemispheres contain a record of Martian environmental conditions. In this study we will assemble a fully three dimensional stratigraphic sequence for the topmost section of the southern layered deposits. A prominent layer sticks out as a bench part-way down the section. We will correlate other layers relative to this one in exposures on opposite ends of the section. In this way we hope to learn how this part of the overall southern layered deposits is organized in three dimensions. The necessary datasets which will be utilized will be hires topographic grids from the Mars Orbiter Laser Altimeter (MOLA) provided by the MOLA team and high resolution Mars Orbiter Camera (MOC) images with spatial resolutions of 1.4 to 12 m/px. Due to continuous repeat coverage of the polar orbiting Mars Global Surveyor and Mars Odyssey (MGS & MO) spacecraft this area has very high coverage. MOC frames almost totally cover the entire exposure which makes it ideal for this kind of study.

Byrne, S.↗
NASA NTRS2003

Analysis of Properties of the North and South Polar Layered Deposits

One of the many questions of Martian exploration is to uncover the history of Mars, through analysis of the polar layered deposits (PLD). Martian polar ice caps hold most of the exposed water ice on the surface of Mars and yet their history and physical processes involved in their formation are unclear. We will attempt to contribute to our knowledge of the composition and stratigraphy of the PLD. In this work we present the latest imaging data acquired by the Mars Odyssey THermal EMission Imaging System (THEMIS) [1] and place it into context of the Mars Global Surveyor (MGS) data. We have discussed the North Polar data in [5]. This work concentrates on data acquired over the South pole of Mars and compares properties of North and South PLD. We are primarily interested in properties of the layers in both ice caps : their continuity, morphology and stratigraphy. These questions can be addressed by THEMIS VIS color images, along with MOC high resolution data and MOLA Digital Elevation Models (DEM). We will investigate thermophysical properties of the layered deposits employing THEMIS IR images. Based on the data obtained by the orbiting spacecraft and described here, we will attempt to expose major directions for modeling and further understanding of the physical processes involved in the formation of the polar layered terrain

Ivanov, A. B.↗