Conference Paper

The Distribution of Crystalline Hematite on Mars from the Thermal Emission Spectrometer: Evidence for Liquid Water

Conference: Lunar and Planetary Science Conference, At Houston Texas USA, Volume: Abstract 1627, Lunar and Planetary Science XXXI
Source: NTRS

ABSTRACT Crystalline hematite on Mars has been mapped using the MGS TES. Two major, and several minor areas of significant accumulation are identified. We favor precipitation models involving Fe-rich water, providing direct mineralogic evidence for large-scale water interactions.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The Thermal Emission Imaging System (THEMIS) on 2001 Mars Odyssey will investigate the surface mineralogy and physical properties of Mars using multi-spectral thermal-infrared images in nine wavelengths centered from 6.8 to 14.9μm, and visible/near-infrared images in five bands centered from 0.42 to 0.86μm. THEMIS will map the entire planet in both day and night multi-spectral infrared images at 100-m per pixel resolution, 60% of the planet in one-band visible images at 18-m per pixel, and several percent of the planet in 5-band visible color. Most geologic materials, including carbonates, silicates, sulfates, phosphates, and hydroxides have strong fundamental vibrational absorption bands in the thermal-infrared spectral region that provide diagnostic information on mineral composition. The ability to identify a wide range of minerals allows key aqueous minerals, such as carbonates and hydrothermal silica, to be placed into their proper geologic context. The specific objectives of this investigation are to: (1)determine the mineralogy and petrology of localized deposits associated with hydrothermal or sub-aqueous environments, and to identify future landing sites likely to represent these environments; (2)search for thermal anomalies associated with active sub-surface hydrothermal systems; (3)study small-scale geologic processes and landing site characteristics using morphologic and thermophysical properties; and (4)investigate polar cap processes at all seasons. THEMIS follows the Mars Global Surveyor Thermal Emission Spectrometer (TES) and Mars Orbiter Camera (MOC) experiments, providing substantially higher spatial resolution IR multi-spectral images to complement TES hyperspectral (143-band) global mapping, and regional visible imaging at scales intermediate between the Viking and MOC cameras. The THEMIS uses an uncooled microbolometer detector array for the IR focal plane. The optics consists of all-reflective, three-mirror anastigmat telescope with a 12-cm effective aperture and a speed of f/1.6. The IR and visible cameras share the optics and housing, but have independent power and data interfaces to the spacecraft. The IR focal plane has 320 cross-track pixels and 240 down-track pixels covered by 10 ∼1-μm-bandwidth strip filters in nine different wavelengths. The visible camera has a 1024×1024 pixel array with 5 filters. The instrument weighs 11.2kg, is 29cm by 37cm by 55cm in size, and consumes an orbital average power of 14W.
    Space Science Reviews 12/2003; 110(1):85-130. · 5.52 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The concentrated crystalline hematite is a unique composition on Mars. A GIS-based study of regional MGS and Viking data sets is underway to shed light on the mysterious mineral deposit. The abstract presents the results of the study.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: 1] Low-frequency sounding radars should be able to probe the Martian subsurface layers down to varying depths, depending on the geoelectrical properties of the sounded sites. We present in this work four frequency-dependent geoelectrical models of the Martian subsurface in the 1–20 MHz frequency band, based on laboratory electromagnetic characterization of Martian soil analogues. Those models correspond to local Martian sites that we considered to be of particular interest in the search for water using mainly the Ground-Penetrating Radar (GPR) instrument of the Netlander mission. Results and discussion are also valid for both sounding experiments MARSIS and SHARAD. The four models of the Martian subsurface are designed to represent terrains where recent fluvial-like features suggest the presence of near-subsurface ground ice and probably liquid water. We performed measurements on volcanic and sedimentary materials that may be present on these sites under the appropriate geophysical conditions that may exist in those terrains. We then simulated the backscattered radar echo arising from each site in the 2 MHz frequency band, using the Finite Difference Time Domain (FDTD) algorithm, in order to evaluate the instrument performances to probe the subsurface stratigraphy of each site. Our results confirm that the near-subsurface rich iron oxide mineralogy controls the instrument performances in terms of penetration depth and signal-to-noise ratio in the 2 MHz frequency band. We finally discuss the geophysical and geoelectrical sounding conditions that could lead to an ambiguous detection of shallow subsurface water on Mars for the Netlander GPR. geoelectrical models of the Martian subsurface for shallow groundwater detection using sounding radars, J. Geophys. Res., 108(E4), 8030, doi:10.1029/2002JE001871, 2003.
    Journal of Geophysical Research Atmospheres 01/2003; 108. · 3.44 Impact Factor

Full-text (3 Sources)

Available from
May 31, 2014