Papers by Emanuele Baratti
The ExoMars 2018 mission (ESA) has for scientific objectives to search for signs of past and pres... more The ExoMars 2018 mission (ESA) has for scientific objectives to search for signs of past and present life on Mars, to investigate the water/geochemical environment as a function of depth in the shallow subsurface, to study to Martian atmospheric trace gases and to characterize the surface environment [1]. The Exomars rover will carry a suite of instruments dedicated to geology and exobiology and will be able to travel a few kilometers searching for past and present traces of life. Its landing ellipse is 19 km by 104 km. The Rover will collect and analyze samples from outcrops and from subsurface drills down to 2 m depth to look for well preserved organic molecules [1]. The landing site has to be relevant with regard to these objectives while fitting the restrictive engineering constrains. From the scientific point of view, the site must be ancient, from the Early Mars period, for which many scientific evidences favor the existence of a water-related cycle. The site must bear abundant morphological and mineralogical evidence of long-lived aqueous activity, the site must expose sedimentary rocks that are good candidates for organic matter preservation and more importantly, the relevant outcrops must be distributed over the landing ellipse to ensure that the rover will have access to one of them within its traverse range, which is restricted to a few (~4) kilometers [1]. In this paper, we present the unique location called Oxia Planum, a wide clay bearing plain located between 16° and 19° North and -23° to -28° East, which has been chosen by ESA as the prime landing site for Exomars 2018 . We will discuss the geological context of these clay-bearing deposits, and the fluvio-lacustrine system observed on the site. We will ultimately discuss the results in term of implications for ancient Mars history and for ExoMars mission.
We suggest the landing of ExoMars in Oxia Planum between 16° and 19° of latitude north and-23° to... more We suggest the landing of ExoMars in Oxia Planum between 16° and 19° of latitude north and-23° to-28° of eastern longitude, and below-2 km of MOLA elevation. This region exhibits one of the widest Mg/Fe phyllosilicates exposures as mapped globally with OMEGA and with CRISM multispectral data. The outcrop of Mg/Fe phyllosilicates is so wide that several potential landing ellipses (19 x 110 km) fitting the engineering constraints is possible. The exposed terrains are 4 Ga old (Hartmann's age system) and have undergone intense erosional processes until 3.6 Ga. The region also reveals fluvial related morphologies such as valleys and a delta fan attesting the water-related history of this region. Moreover, the region is current under erosion so that the exposition age of the fresher phyllosilicate rich surfaces is younger than 100 My attesting the potential preservation of putative biosignature. This proposed site fulfills ExoMars objectives.
One of the most interesting morphological feature on the surface of Mars are paleolakes: time cap... more One of the most interesting morphological feature on the surface of Mars are paleolakes: time capsules and low-energy depositional settings that preserve hints on the ancient environment and, possibly, traces of life. On Earth, lakes host a huge diversity of habitats where life is flourishing; hence, on Mars, they may have once supported life too. In order to understand the paleohydrology of these basins, the estimation of the water discharge flowing into their tributary and/or outlets can give important clues on the water cycle on the planet. On Mars, the most common modeling used to reconstruct the hydraulic properties are based on the adaptation of terrestrial empirical relationship, less focusing on more sophisticated hydraulic models. The main objective of this study is to separately analyze the hydraulic characteristics of the tributary and the outlet of a paleolake located in the Menmonia quadrangle by using an hydraulic model based on the energy and momentum equations of the body of water enclosed in the channels. The lengths of the analyzed river reaches are ∼ 10 km and ∼ 19 km, the outlet and the tributary respectively. A Monte Carlo procedure coupled to geomorphological evidences of the paleowater surface (e.g. terraces levels) were used to constrain the hydraulic parameters of the system. The Mars Express High-resolution stereo camera digital elevation model, H31850000DA4 with a spatial resolution on 75 m, is hence used to characterize the geometry of the study area. In this contribution we provide estimates on the magnitude of the bankfull discharge and roughness coefficient of the tributary and the outlet of the paleolake; moreover, on the basis of these results, the probable water depth of the lake is inferred. Finally, a discussion on the possibility that the system inlet-lake-outlet was acting simultaneously is also presented. Consequently, a sensitivity analysis is performed to examine the accuracy of the results to the main sources of uncertainty concerning the methodology, as well as, the uncertainty in the geomorphological evidences used to constrain the hydraulic modelling. Given the comparable discharge estimates of the tributary and the outlet, as well as the coherent elevation and width of their mouths into the lake, the results suggest that both channels were most probably acting simultaneously during their last evolutionary phase, with a discharge equal to ∼ 6000 m 3 s −1 and a water surface elevation in the lake equal to ∼-1400 m. This contribution supports the hypothesis of an ancient and articulated hydrologic system acting in the study area.
The landing sites we are proposing for the next Mars 2020 rover span between 28 • 29'30"S-28 • 53... more The landing sites we are proposing for the next Mars 2020 rover span between 28 • 29'30"S-28 • 53'0"S Latitude and 178 • 56'30"W • 178 • 28'0"W Longitude, i.e. on the NE floor of a 1.1×10 6 km 2 closed drainage basin . This area, see , belongs to the bigger (3×10 6 km 2 ) Eridania basin that gave birth to the Ma'adim Vallis through catastrophic overflow, and presenting a water table between 950 and 1250 m [1,2,3]. The crater counting chronology for this area gives an age between Early to Middle Noachian .
This contribution presents the results of a detailed hydraulic study of the tributary and the out... more This contribution presents the results of a detailed hydraulic study of the tributary and the outlet of a Martian paleolake located in the Memnonia quadrangle between 167 • 0'0 " W and 167 • 20'0 " W longitude and between 9 • 25'0 " S and 9 • 45'0 " S latitude [1] (Fig. 1). We used an hydraulic model capable of performing one-dimensional water surface profile calculations for steady gradually varied flow in natural channels adapted to the Martian conditions (e.g. martian gravity equal to 0.38 Earth's) [2]. Geomorphic evidences, i.e. fluvial terraces, were used to identify the probable bankfull level of the tributary and the outlet [2,3,4]. The identified terracing levels were used to constrain the past water discharge flowing on the surface, the Manning's roughness coefficient of the channels and the water level of the paleolake. The Mars Express high-resolution stereo camera digital elevation model, HRSC DEM, H31850000DA4, presents a spatial resolution of 75 m and it was used to characterize the geometry of the channels, i.e. their cross sections and the fluvial terraces elevation. The outlet and the tributary reaches are 10.0 km-long and 22.2 km-long, respectively. Fifty-one cross-sections along the outlet were extracted from the DEM and were used to characterize the geometry of this river-reach in the hydraulic model, whereas the hydraulic model of the tributary is composed of 111 cross sections. The mean distance between cross sections is ∆x = 200 m. Fig 1 shows the upper and the lower cross sections for both the outlet and the tributary studied through the above mentioned hydraulic model. Note that the water surface profiles are computed from one cross section to the following one by solving the Energy equation through an iterative procedure called the standard step method [5]; where the energy equation is not considered applicable, we computed the wa-Figure 1: Context map of the case study area showing HRSC H3185000DA4 DEM elevation values in meters , the latitude and longitude grid and a scale bar reference. The upper and lower cross section of the outlet (red) and the tributary (white) are marked.
Hydrology and Earth System Sciences Discussions, 2014
Reproducibility and repeatability of experiments are the fundamental prerequisites that allow res... more Reproducibility and repeatability of experiments are the fundamental prerequisites that allow researchers to validate results and share hydrological knowledge, experience and expertise in the light of global water management problems. Virtual laboratories offer new opportunities to enable these prerequisites since they allow experimenters 5 to share data, tools and pre-defined experimental procedures (i.e. protocols). Here we present the outcomes of a first collaborative numerical experiment undertaken by five different international research groups in a virtual laboratory to address the key issues of reproducibility and repeatability. Moving from the definition of accurate and detailed experimental protocols, a rainfall-runoff model was independently applied to 10 15 European catchments by the research groups and model results were collectively examined through a web-based discussion. We found that a detailed modelling protocol was crucial to ensure the comparability and reproducibility of the proposed experiment across groups. Our results suggest that sharing comprehensive and precise protocols and running the experiments within a controlled environment (e.g. virtual laboratory) 15 is as fundamental as sharing data and tools for ensuring experiment repeatability and reproducibility across the broad scientific community and thus advancing hydrology in a more coherent way.
Hydrology and Earth System Sciences, 2012
We propose an original approach to infer the flood frequency distribution at seasonal and annual ... more We propose an original approach to infer the flood frequency distribution at seasonal and annual time scale. Our purpose is to estimate the peak flow that is expected for an assigned return period T , independently of the season in which it occurs (i.e. annual flood frequency regime), as well as in different selected sub-yearly periods (i.e. seasonal flood frequency regime). While a huge literature exists on annual flood frequency analysis, few studies have focused on the estimation of seasonal flood frequencies despite the relevance of the issue, for instance when scheduling along the months of the year the construction phases of river engineering works directly interacting with the active river bed, like for instance dams. An approximate method for joint frequency analysis is presented here that guarantees consistency between fitted annual and seasonal distributions, i.e. the annual cumulative distribution is the product of the seasonal cumulative distribution functions, under the assumption of independence among floods in different seasons. In our method the parameters of the seasonal frequency distributions are fitted by maximising an objective function that accounts for the likelihoods of both seasonal and annual peaks. In contrast to previous studies, our procedure is conceived to allow the users to introduce subjective weights to the components of the objective function in order to emphasize the fitting of specific seasons or of the annual peak flow distribution. An application to the time series of the Blue Nile daily flows at the Sudan-Ethiopia border is presented.
ABSTRACT Flood frequency analysis is often used by practitioners to support the design of river e... more ABSTRACT Flood frequency analysis is often used by practitioners to support the design of river engineering works, flood miti- gation procedures and civil protection strategies. It is often carried out at annual time scale, by fitting observations of annual maximum peak flows. However, in many cases one is also interested in inferring the flood frequency distribution for given intra-annual periods, for instance when one needs to estimate the risk of flood in different seasons. Such information is needed, for instance, when planning the schedule of river engineering works whose building area is in close proximity to the river bed for several months. A key issue in seasonal flood frequency analysis is to ensure the compatibility between intra-annual and annual flood probability distributions. We propose an approach to jointly estimate the parameters of seasonal and annual probability distribution of floods. The approach is based on the preliminary identification of an optimal number of seasons within the year,which is carried out by analysing the timing of flood flows. Then, parameters of intra-annual and annual flood distributions are jointly estimated by using (a) an approximate optimisation technique and (b) a formal maximum likelihood approach. The proposed methodology is applied to some case studies for which extended hydrological information is available at annual and seasonal scale.
Liquid water was flowing on the surface of Mars in the past, leaving behind a wide range of geomo... more Liquid water was flowing on the surface of Mars in the past, leaving behind a wide range of geomorphic features. The ancient major Martian water fluxes vanished about 3.5 Ga. Meteoritic impacts, wind-erosion, gravity-related phenomena, tectonic deformations and volcanic activities deeply altered the landforms during the ages. Hence, the reconstruction of water-shaped landscapes is often complicated. Fluvial and lacustrine terraces analysis and correlation is a useful approach to understand and reconstruct the past changes in Martian landscape evolution. These features are commonly used as reference for the top of water bodies on Earth, since they are void of the uncertainties or errors deriving from erosional or slumping processes that could have acted on the valley flanks or in the plateau, where the hydrological network was carved in. The study area is located in the western hemisphere of Mars, in the Memnonia quadrangle, between latitude 9˚10'-9˚50'South and longitude 167˚0'-167˚30' West and it constitutes a transition region between the southern highlands of Terra Sirenum and the northern lowlands of Lucus Planum. Many water-shaped features have already been described near the study area, the most prominent of them being the Ma'adim Vallis and the Mangala Valles system. Our results derive from the observations and the analysis of HRSC images (12.5 m spatial resolution) and Digital Elevation Models (DEMs) derived from the MEX-HRSC (75 m resolution), that allow the identification of elevation differences up to the tens of meter scale. We were able to reconstruct six main evolutionary stages of a complex hydrologic systems consisting of two main palaeorivers (up to 5 km wide) connected one another by a palaeolake that formed within a meteor crater (∼20 km diameter). On the basis of Earth analogs, these stages/terraces should have evolved during a long period of time, at least thousands years long. Furthermore, crater counting date back the deactivation of the system to ca 3.5±0.1 Ga ago, suggesting the presence of a stable environment with subaerial water fluxes during the Late Hesperian, very close to the liquid-water disappearance. Apart from the above mentioned reasons, the increasing interest and ongoing programs of on-site Martian exploration are additional reasons to study fluviolacustrine depositional environments. Together with the technology improvements that lead to more flexible safety constraints for landing/exploring, the possibility to focus on specific and more detailed scientific aspects is enhanced.
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Papers by Emanuele Baratti