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Research theme

Milos Rajkovic aka Sholim

Geosciences and planetary sciences

The seasonal south polar cap of Mars

Clathrates, zeolites and methane in the history of Mars

The flows on Mars

Evolution of terrestrial and planetary topographies

Climate archives


Exoplanets and habitability


Hyperspectral imaging

Spectro-photometric imaging


The seasonal south polar cap of Mars

The seasonal south polar cap (SSPC) of Mars has interesting features, partially updated by my analyzes of the hyperspectral data of the OMEGA instrument. The SSPC is composed mainly of CO2 ice and covers the surface during the polar winter up to 40°S latitude. I was able to show that the speed of retreat is mainly controlled by albedo. The darkest region, known as the "cryptic region", has many dark spots on a scale of a few meters that influence the overall dynamics. Geomorphological studies suggest that several dynamic phenomena occur (geysers, spiders and dark flows). Several physical models have been proposed. However, the lack of observational constraints does not make it possible to identify the processes at work on Mars. My most recent work consists in establishing a maximum of quantitative information (spectroscopic, geomorphological, ...) in order to establish the origin of these phenomena. In particular, the detection of traces of water ice in these areas must be taken into account. These works have for perspective a better understanding of the exchanges of volatiles on Mars now and in the past.

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• Schmidt F., Douté S., Schmitt B., Vincendon, M., Langevin, Y., Bibring J.-P. and the OMEGA Team ; “Albedo control of the Seasonal South Polar Cap recession”; Icarus, 2009, 200, 374-394

• Schmidt F., Schmitt B., Douté S., Forget, F., Jeng, J.-J., Martin, P., Langevin, Y., Bibring J.-P. and the OMEGA Team ; “Sublimation of the Martian CO2 seasonal south Polar Cap”, Planetary and Space Science, 2010, 58, 1129- 1138

• Kereszturi A., Vincendon M., Schmidt F., “ Water ice in the dark dune spots of Richardson crater on Mars ”, Planetary and Space Science, 2011, 59, 26-42

• Jouannic, G., Gargani, J., Costard, F., Ori, G. G., Marmo, C., Schmidt, F. & Lucas, A. (2012), “ Morphological and mechanical characterization of gullies in a periglacial environment: The case of the Russell crater dune (Mars) ”, Planetary and Space Science, 71, 38-54

• Andrieu, F., Douté S., Schmidt, F., & Schmitt, B. (2015) “ Radiative transfer model for contaminated rough slabs ”, Applied Optics, 54, 9228

• Andrieu, F.; Schmidt, F.; Schmitt, B.; Douté, S. & Brissaud, O. Retrieving the characteristics of slab ice covering snow by remote sensing, The Cryosphere, 2016, 10, 2113-2128

• Andrieu, F., Schmidt, F., Douté, S., Chassefière, E., Ice state evolution in Richarsdon crater, Mars during spring, Icarus, in review

Clathrates, zeolites and methane in the history of Mars

Clathrates hydrates are exotic chemical forms on Earth: cage-shaped water ice crystals that can trap one or more molecules of gas. Physicists and thermodynamicians have established more and more precise models of these structures whose implications have been little discussed in planetary sciences. More precisely, the conditions of the primordial atmosphere from Mars to Noachian, under the probable conditions of stability of H2O, CO2 and SO2 could allow the formation of mixed clathrate of CO2 and SO2. Since SO2 is more stable than CO2 in cages, first a massive accumulation of SO2 could occur, followed by a catastrophic release of at the transition Noachian-Hesperian epoch, in agreement with the observed thick layers of sulphates. Several data have shown the presence of methane currently on Mars with a seasonal evolution. If serpentinization is the most likely process, for methane production, sporadic release remains unexplained. Solid phases with strong gas trapping abilities such as clathrates or zeolites could be involved. The challenge of this research program is to understand the history of Martian volatiles by taking into account all available information (thermodynamics, physics, geomorphology).

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• Mousis, O., Chassefière, E., Lasue, J., Chevrier, V., Elwood Madden, M., Lakhlifi, A., Lunine, J., Montmessin, F., Picaud, S., Schmidt, F. & Swindle, T. D. (2013), « Volatile Trapping in Martian Clathrates», Space Science Reviews, 174, 213-250

• Chassefière, E., Dartois, E., Herri, J.-M., Tian, F., Schmidt, F., Mousis, O. & Lakhlifi, A. (2013), « CO2- SO2 clathrate hydrate formation on early Mars », Icarus, 223, 878-891

• Schmidt, F. , Chassefière, E., Tian, F., Dartois, E., Herri, J.-M., and Mousis, O., (2016) « Early Mars volcanic sulfur storage in the cryosphere and formation of transient SO2-rich atmospheres during the Hesperian », Meteoritics & Planetary Sciences, 51, 2226-2233

• Mousis, O.; Simon, J.-M.; Bellat, J.-P.; Schmidt, F.; Bouley, S.; Chassefière, E.; Sautter, V.; Quesnel, Y.; Picaud, S. & Lectez, S.. (2016), « Martian zeolites as a source of atmospheric methane », Icarus, Elsevier BV, 278, 1-6

The flows on Mars

In the distant past, Mars has most likely been favourable to life because there are traces of ancient rivers, presumably created by liquid water. Since the current activities of the RSL (Recurring Slope Lineae) have been observed, a significant part of the scientific community has considered liquid water as a plausible at present-time. The main argument for the presence of liquid water was based on the fact that RSLs are active today in the hottest places of Mars, ie the conditions closest to the triple point of water. In addition, spectroscopic signatures of hydrates minerals have been reported. However, it was only indirect evidence (detection of salts but no liquid water). In addition, recent studies have shown that neither internal water sources nor atmospheric water sources are realistic. On the other hand, there is no water signature in the thermal measurements. The origin of these flows then remained mysterious. I proposed a new mechanism based on the Knudsen pump that does not require liquid water. This mechanism is only active in the hottest places of Mars. Because of the temperature variations in the soil, the gas contained in the pores flows. During the few minutes after the appearance of the shadow of a rock, the flow of gas is fast enough that it can destabilize the granular material and create a flow. This process has been modelled numerically and the predicted activity is compatible with observed RSL activities. Considering that RSLs were the main figures proposed to justify the presence of liquid water today on Mars, this new natural pump process seems to rule out this hypothesis. These new results have an obvious impact on the possibility of finding life on the Red Planet, but also portray an inhospitable planet for human exploration.

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• Schmidt, F., Andrieu, F., Costard, F., Kocifaj, M. & Meresescu, A. (2017), « Formation of recurring slope lineae on Mars by rarefied gas-triggered granular flows », Nature Geoscience

• Schmidt, F., Portynakina G., Active geomorphological process involving exotic agent, in book “ Dynamic Mars ”, 2018

Evolution of terrestrial and planetary topographies

The topography of planetary surfaces records the dynamic equilibrium of several processes. By describing in detail the topography, I wish to quantify the processes governing it. Multiscale analyzes have shown the presence of fractal scale-symmetry of planetary surfaces. However, since 1990, several studies have given different and inconsistent fractal geometries. More recently, multi-fractal theory accounts for intermittency (smooth and rough surface) while preserving scale symmetry. We were able to show that the Martian surface had a multi-fractal symmetry at scales larger than 10 km but simply fractal for scales smaller than 10 km. More in-depth analyzes will make it possible to decipher the processes at the origin of these differences (erosion, tectonics, meteoric bombardment, etc.). An application on well-documented terrestrial sites is underway, particularly in Taiwan.

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Publications scientifiques :

• Landais, F., F. Schmidt, and S. Lovejoy (2015), « Universal multifractal Martian topography », Nonlinear Processes in Geophysics, 22, 713-722

• Landais, F., F. Schmidt, and S. Lovejoy (2018), « Multifractal topography of several planetary body in the Solar System », Icarus, under review

Climatic archives

Current climate change, in part due to the increase in anthropogenic greenhouse gases, is disrupting the development of human activities. In the past, these climatic changes have had consequences on the biosphere but also on the erosion of the reliefs. To better understand them and anticipate them, I study climatic recordings and in particular marine sediments. These can come from primary minerals in mountainous areas or from mature soils that have undergone a greater chemical alteration. My goal is to decipher these climate archives by improving the quantification of the different sources.

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• Joussain, R.; Colin, C.; Liu, Z.; Meynadier, L.; Fournier, L.; Fauquembergue, K.; Zaragosi, S.; Schmidt, F.; Rojas, V. & Bassinot, F. Climatic control of sediment transport from the Himalayas to the proximal NE Bengal Fan during the last glacial-interglacial cycle, Quaternary Science Reviews, 2016, 148, 1-16

• Zhao, Y., Colin C., Liu Z., Schmidt, F., Siani G., Bonneau L., and Revel M.. « The Quaternary history of riverine and eolian sediment inputs to the Nile deep-sea fan», Palaeogeography, Palaeoclimatology, Palaeoecology, 2017, under review


The control of water resources is one of the major challenges of the 21st century. When a rainy episode falls on a mountainous massif, a part of the water flows on the surface, a part penetrates in the ground and a part infiltrates to reload the aquifers. The spread between the meteorological rain and the arrival in the water table is crucial to understand the exchanges, both from the point of view of the water resource, and of mineralization. I study the temporal aspect of water propagation using non-invasive deconvolution methods.

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• Meresescu A., Kowaslki M., Schmidt, F., and Landais, F., « Water Residence Time Estimation through 1D Deconvolution in the form of a l2 Regularized Inverse Problem with Smoothness, Positivity and Causality Constraints », under review, Computers and Geoscience

Exoplanets and habitability

The discovery of the exoplanet has profoundly changed our place of the universe. Thanks to the technological developments, it is possible to have information on these distant worlds thanks to spectroscopy. One of the major issues is the habitability of these planets. To say that an exoplanet is home to a life form similar to the Earth, several criteria can be proposed, such as the presence of methane and O2 on the same planet. We must be very careful not to confuse an exomoon, with atmosphere of methane, orbiting a planet with O2. I proposed a method that eliminates candidates from false positives.

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• Cui W., Schmidt F., Tian F., Cui D., Li T., Huang X. , « On Biosignature Detection and Surface Characterization of Nearby Rocky Exoplanets», PNAS, submitted, 2017

Hyperspectral imaging

Hyperspectral imagery is a technique that records the light flux as a function of wavelength and space. Beyond the technical issues of realization and calibration of such instruments onboard space exploration probes, this type of data poses problems of digital processing. During my research, I developed various tools for the automatic detection of chemical compounds in hyperspectral images. WAVANGLET, is a method based on Daubechies’ fast wavelet transform which allows a detection of water and CO2 ice on the surface of Mars, independently of the geometry of observation. This method allowed the detection of ice on all OMEGA data, representing 1000 images of 100,000 spectra each. On the other hand, the Bayesian Prior Source Separation (BPSS) program is a blind source separation method based on Bayesian theory and solved by a Monte Carlo algorithm. Thanks to data pre-processing, the initial version of BPSS showed that this type of approach allowed for the automatic and unsupervised detection (without reference spectrum) of ice on Mars, thus confirming their presence. However, this initial release of BPSS did not allow an application to an entire hyperspectral cube. Thanks to an optimization of the implementation, we have been able to reduce the computation time to allow the application on an image in a shorter time (from a few days to a few hours). This type of method has also been validated on planetary data thanks to independent measurements. Finally, the LinMin method, is a fast method, implemented on GPU (Graphic Processing Unit), which allows the robust detection of minerals with a computation time of the order of the minute for a hyperspectral image and very promising for the analysis of vast datasets.

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• Schmidt F.; Douté S. and Schmitt B., “WAVANGLET: an efficient supervised classifier for hyperspectral images”; IEEE Transactions on Geoscience and Remote Sensing, 2007, 45, 1374-1385

• Moussaoui, S.; Hauksdóttir, H.; Schmidt, F.; Jutten, C.; Chanussot, J.; Brie, D.; Douté, S. & Benediktsson, J., “On the Decomposition of Mars Hyperspectral data by ICA and Bayesian positive source separation”; Neurocomputing, Neurocomputing for Vision Research; Advances in Blind Signal Processing, 2008, 71, 2194-2208

• Schmidt, F.; Schmidt, A.; Tréguier, E.; Guiheneuf, M. and Moussaoui, S. & Dobigeon, N., Implementation strategies for hyperspectral unmixing using Bayesian source separation, IEEE Transaction on Geoscience and Remote Sensing, 2010, 48, 4003-4013

• Ceamanos, X.; Douté;, S.; Luo, B.; Schmidt, F.; Jouannic, G. & Chanussot, J., Intercomparison and Validation of Techniques for Spectral Unmixing of Hyperspectral Images: A Planetary Case Study, IEEE Transaction on Geoscience and Remote Sensing, 2011, 1-18

• Themelis, K. E.; Schmidt, F.; Sykioti, O.; Rontogiannis, A. A.; Koutroumbas, K. D. & Daglis, I. A., On the unmixing of MEx/OMEGA hyperspectral data, Planetary and Space Science, 2012

• Schmidt, F., Legendre, M. & Le Mouëlic, S. (2014), « Minerals detection for hyperspectral images using adapted linear unmixing: LinMin », Icarus, 237, 61-74

Spectro-photometric imaging

Spectro-photometric imaging adds an extra dimension to the hyperspectral imagery previously described: the geometry. Each pixel on the ground is observed both at different wavelengths but also at different geometries (angle of emergence), thus sampling bidirectional reflectance (BRDF). Each geometry is called angel (for angular element), similar to pixel (picture element). We have developed a tool to estimate the properties of granular surfaces (roughness, albedo and grain shape) from BRDFs. For the first time, this tool allows, in one hand to get rid of atmospheric aerosols, but also in the order hand to perform a Bayesian inversion quickly. We validated this tool through a comparison with data from Martian rovers in situ. This innovative tool offers the prospect of a better characterization of the different Martian geological units (volcanic and sedimentary contexts). We demonstrated that the Martian surface is the only body except the Earth that have forward scattering terrains, most probably due to the presence of grains, rounded by liquid water transportation.

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• Ceamanos, X., Doute, S., Fernando, J., Schmidt, F., Pinet, P. & Lyapustin, A. (2013), « Surface reflectance of Mars observed by CRISM/MRO: 1. Multi-angle Approach for Retrieval of Surface Reflectance from CRISM Observations (MARS-ReCO) », Journal of Geophysical Research, 118, 1-20

• Fernando, J., Schmidt, F., Ceamanos, X., Pinet, P., Douté, S. & Daydou, Y. (2013), « Surface reflectance of Mars observed by CRISM/MRO: 2. Estimation of surface photometric properties in Gusev Crater and Meridiani Planum », Journal of Geophysical Research, 118, 1-26.

• Fernando, J., Schmidt, F., Pilorget, C., Pinet, P., Ceamanos, X., Douté, S., Daydou, Y. & Costard, F. (2015), « Characterization and mapping of surface physical properties of Mars from CRISM multi-angular data: Application to Gusev Crater and Meridiani Planum », Icarus , 253, 271 - 295

• Schmidt, F. & Fernando, J. (2015), « Realistic uncertainties on Hapke model parameters from photometric measurement », Icarus , 260, 73 - 93

• Pilorget, C., Fernando, J., Ehlmann, B., Schmidt, F. & Hiroi, T. (2016), « Wavelength dependence of scattering properties in the VIS-NIR and links with grain-scale physical and compositional properties », Icarus, 267, 296-314

• Fernando. J., Schmidt, F. and Douté S., (2016) « Martian surface microtexture from orbital CRISM multi-angular observations: new perpectives for the characterization of the geological processes », Planetary and Space Science, 128, 30-51

• Schmidt, F. & Bourguignon, S. (2017), « Efficiency of BRDF sampling and bias on the average photometric behavior », Icarus , in revision


The high-resolution spectral data from the Planetary Fourier Spectrometer (PFS) have been used to determine the thermal structure of the Martian atmosphere, but also to determine the minor compounds, including methane which is still controversial. Unfortunately, PFS data is subject to structured noise from the microvibrations induced by the environment. The objective of this project is to correct the data by using deconvolution in a blind way: without assuming a spectrum of Mars, nor a form of "noise". The goal is to analyze more finely the surface and the atmosphere of Mars. From a methodological point of view, blind deconvolution is a difficult problem that we want to attack by adding a maximum of mathematical assumptions (positivity, sparsity, redundancy, ...).

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• Shatalina, I., Schmidt, F., Saggin, B., Gac, N., Kowalski, M. & Giuranna, M. (2013), « Analytical model and spectral correction of vibration effects on Fourier transform spectrometer », Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, , 8890

• Schmidt, F., Shatalina, I., Kowalski, M., Gac, N., Saggin, B. & Giuranna, M. (2014), « Toward a numerical deshaker for PFS », Planetary and Space Science, 91, 45-51

IDES Université Paris-Sud 11 CNRS Faculté des Sciences
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