Description of CoTCAT (Complement to CRISM Analysis Toolkit)

Bultel, B.; Quantin, C.; Lozac’h, L.

doi:10.1109/jstars.2015.2405095

Cited by 10 publications

(5 citation statements)

References 30 publications

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“…Hence, a median ratio was used to highlight absorptions. Each pixel of a column is divided by the median spectrum calculated from the whole column following the procedure described in Bultel et al (). All spectra were then analyzed by a minimal spatial median on 5 × 5 pixels for each region of interest.…”

Section: Methodsmentioning

confidence: 99%

Detection of Carbonates in Martian Weathering Profiles

et al. 2019

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Noachian surfaces on Mars exhibit vertical assemblages of weathering horizons termed as weathering profiles; this indicates that surface water caused alteration of the rocks that required a different, warmer climate than today. Evidence of this early Martian climate with CO2 vapor as the main component causing greenhouse warming has been challenged by the lack of carbonate in these profiles. Here we report the analysis of Compact Reconnaissance Imaging Spectrometer for Mars L‐detector data leading to the detections of carbonates using a spectral signature exclusively attributed to them. The carbonates are collocated with hydroxylated minerals in weathering profiles over the Martian surface. The origin of CO2 for the formation of carbonates could be the atmosphere. The widespread distribution of weathering profiles with carbonates over the surface of the planet suggest global interactions between fluids containing carbonate/bicarbonate ions with the surface of Mars in the presence of atmospheric water until around 3.7 billion years ago.

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Section: Methodsmentioning

confidence: 99%

Detection of Carbonates in Martian Weathering Profiles

et al. 2019

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“…The instrument has been in operation for almost a decade and the SNR is expected to have degraded to approximately 200 at 2.3 μm but have remained around 100 at 0.4 μm (Bultel et al. ). Therefore, to better represent instrument data, Poisson‐distributed random white noise (Kreisch et al.…”

Section: Methodsmentioning

confidence: 99%

Hapke mixture modeling applied to VNIR spectra of mafic mineral mixtures and shergottites: Implications for quantitative analysis of satellite data

Harris

Grindrod

2018

Meteorit & Planetary Scien

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Abstract-The mineralogy of Mars is well understood on a qualitative level at a global scale due to satellite data. Quantitative analysis of visible and near-infrared (VNIR) satellite data is a desirable but nontrivial task, due partly to the nonlinearity of VNIR reflectance spectra from the mineral mixtures of the Martian surface. In this study, we investigated the use of the Hapke radiative transfer model to generate linearly mixed single scattering albedo data from nonlinearly mixed VNIR reflectance data and then quantitatively analyzed them using the linear spectral mixture model. Simplifications to the Hapke equation were tested accounting for variables that would be unknown when using satellite data. Mineral mixture spectra from the RELAB spectral library were degraded to test the robustness of the unmixing technique in the face of data that mimic some of the complexities of satellite spectral data collected at Mars. A final test was performed on spectra from shergottite meteorites to assess the technique against real Martian mineral mixtures. The simplified Hapke routine produced robust abundance estimates within 5-10% accuracy when applied to laboratory standard spectra from the synthetic mixtures of igneous minerals in agreement with previous studies. The results of tests involving degraded data to mimic the low spectral contrast of the Martian surface and the lack of a priori knowledge of the constituent mineral spectral endmembers, however, were less encouraging, with errors in abundance estimation greater than 25%. These results cast doubt on the utility of Hapke unmixing for the quantitative analysis of VNIR data of the surface of Mars.

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“…Table 1 lists the main characteristics of the selected cubes (i.e., labels, coordinates, and collection dates). All FRS cubes were acquired quite recently (2014-2016) and hence are noisier owing to the aging of the instrument and the failing of a cryocooler (e.g., Parente et al 2010;Bultel et al 2015). Only the FRT cube (i.e., FRT0A605) was collected during the nominal phase of the MRO mission (2007MRO mission ( -2008.…”

Section: Spectral Analysismentioning

confidence: 99%

“…Corrected cubes are later processed in IDL (v.8.6), where we have calculated a column-by-column ratio, with the featureless median spectrum of the column as the denominator (Altieri et al 2021;Brossier et al 2022a). Such a procedure aims to greatly reduce noise and residual atmospheric contributions and emphasize mineralogical absorptions in the "ratioed" spectrum (see also Bultel et al 2015).…”

Section: Spectral Analysismentioning

confidence: 99%

Spectral Analysis of Clay-bearing Outcrops in Northern Xanthe Terra, Mars: Comparison with Oxia Planum, the Landing Site for the ExoMars Rover Mission

et al. 2023

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Clay minerals detected on Mars are valuable targets to seek traces of life on the planet, where biosignatures might be preserved. Here, we report an in-depth spectral analysis of clay-rich outcrops identified in northern Xanthe Terra (300°–320° E, 10°–20° N). We focused particularly on the absorptions centered in the 1.0–2.6 μm spectral range to (1) constrain the mineralogy of the clay outcrops, (2) map their strength and distribution throughout the region, and thus (3) develop a better understanding of the geologic environment at circum–Chryse Planitia. We then compared the infrared signatures in Xanthe Terra and Oxia Planum. Like in Oxia Planum, Xanthe’s clays are consistent with either Fe-bearing saponites or vermiculites. However, the spectral signatures in Xanthe are weaker relative to Oxia Planum, perhaps due to significant dust cover in the region. Besides the spectral signatures, northern Xanthe Terra displays several morphological features similar to Oxia Planum, indicating long-lasting aqueous activity (fluvial channels and fan deltas). Clays found at the fan deltas could be detrital (fluvial transport) or authigenic (lacustrine or deltaic sedimentation), while the origin of clays seen elsewhere on the surrounding plateaus remains undetermined. Oxia Planum has been selected as the landing site for ESA’s ExoMars “Rosalind Franklin” rover, where its instruments will search for signs of life and constrain the nature and origin of the clays. This exploration will indubitably provide new clues on the clays found in the circum-Chryse basin.

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Description of CoTCAT (Complement to CRISM Analysis Toolkit)

Cited by 10 publications

References 30 publications

Detection of Carbonates in Martian Weathering Profiles

Detection of Carbonates in Martian Weathering Profiles

Hapke mixture modeling applied to VNIR spectra of mafic mineral mixtures and shergottites: Implications for quantitative analysis of satellite data

Spectral Analysis of Clay-bearing Outcrops in Northern Xanthe Terra, Mars: Comparison with Oxia Planum, the Landing Site for the ExoMars Rover Mission

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