Results from the First Field Tests of the WISDOM GPR (2018 ExoMars Mission)

International audienceIntroduction: The WISDOM (Water Ice Subsur- face Deposit Observation on Mars) Ground Penetrating Radar (GPR) is one of the instruments that have been selected as part of the Pasteur payload of ESA’s 2018 ExoMars Rover mission[1]. The Pasteur payload actu- ally consists of two different sets of instruments: the Panoramic Instruments, which include a wide angle camera and the WISDOM radar, that will be used to perform large-scale scientific investigations of the landing site and the Analytical Laboratory Instruments that will analyze the core samples obtained by the sub- surface drill. WISDOM will help identify the location of sedimentary layers, where organic molecules are the most likely to be found and well-preserved. WISDOM has been designed to investigate the near subsurface environment down to a depth of ~2-3 m with a vertical resolution of a few centimeters [2]. WISDOM is a step frequency radar operating over a wide frequency band between 0.5 and 3 GHz. Particular attention was paid to the design of the antenna system, which needs to be able to conduct polarimetric measurements over the whole bandwidth without significant distortion [3]

Corob-x: a cooperative robot team for the exploration of lunar skylights

The project CoRob-X develops and demonstrates enabling technologies for multi-agent robotic teams to explore planetary surfaces with a focus on hard-to-reach areas where a collaborative scheme is required to efficiently explore complex environments. Exploring lava tubes is such a challenging environment and requires a team of robots able to collaborate in an autonomous way to find their way to the subsurface tube system, descend through a natural entry hole (the so-called skylight), and explore the interior with payload instruments to provide scientific data. The developed robotic exploration system that will tackle the ambitious goal is composed of three rovers with substantially different technical characteristics. The paper presents the overall approach, i.e., the control architecture, the robotic systems, and the software to be used. It also showcases the selected mission phases that will be demonstrated in a field-test campaign. In addition, a terrestrial mining use case is presented that demonstrates how the developed autonomy-enabling software can be transferred to terrestrial applications.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

WISDOM measurements in a cold artificial and controlled environment

The WISDOM (500MHz - 3GHz) GPR is one of the instruments that have been selected as part of the Pasteur payload of ESA's 2018 ExoMars Rover mission. One of the main scientific objectives of the mission is to characterize the nature of the shallow sub-surface on Mars and WISDOM has been designed to explore the first ~ 3 meters of the subsurface with a vertical resolution of a few centimetres. Full polarimetric measurements in cold artificial and controlled conditions have been performed by the prototype to illustrate and quantify the instrument performance. Preliminary results are presented

WISDOM GPR performance assessment in a cold artificial environment

The WISDOM (Water Ice Subsurface Deposit Observation on Mars) GPR is one of the instruments that have been selected as part of the Pasteur payload of ESA's 2018 ExoMars Rover mission. WISDOM has been designed to obtain information about the nature of the subsurface along the rover path with the objective to explore the first ~ 3 m of the soil with a vertical resolution of a few centimetres. The sub-surface properties that can be addressed with WISDOM are variations in composition, texture, stratification (e.g., number, thickness and orientation of layers), the presence of unconformities and other structural characteristics (such as fractures and the deformation of strata). It is then essential to quantify the performances of WISDOM in controlled conditions, and several full polarimetric measurements have been carried out with the prototype in a cold artificial environment. The main objectives are the detection of different interface between homogeneous materials with WISDOM. The characterization of the material (porosity, % of water, dielectric properties, thickness and depth, temperature ...) is well-controlled. The cold room facility of IDES at Orsay (France) has been used, the ambient temperature ranged from -7° C to -10° C. A tank laying on the metallic floor (height: 0.5m, width: 0.80 m, length: 1.20m) in macrolon can contain liquid or frozen water or layers (dielectric contrasts) of home-maid permafrost (frozen saturated sand) with and without embedded objects or fractures. The temperature inside the medium (ice or permafrost) is controlled, the radar antennas are put on a sheet of polystyrene over the tank. Frequent measurements were performed (every 2cm) along a track from one side to the other side of the tank. The experimental conditions were: (1)dry cold sand (Fontainebleau sand) : porosity 35% density 2,67 (2) saturated wet sand : 35% of water (3) permafrost (frozen saturated sand) : 35% of ice content 1 layer: 3 consecutive experiments : 10cm dry sand ( 1) 10cm saturated sand (2) 10cm permafrost(3) 2 layers :previous 10cm permafrost in the bottom +3 consecutive experiments : 10cm dry sand ( 1) 10cm saturated sand (2) 10cm permafrost(3) . Basalt rocks and air fractures are or are not embedded in the layers Values of the permittivity of dry sand and permafrost were retrieve by two different ways. 1.Retrieval of the sand and permafrost permittivity from delay measurements knowing the layer thickness d ɛr = ct/2d = n2 2. Retrieval of the sand and permafrost permittivity from amplitude measurements knowing a calibration reference (reflection over a metallic plate), R is the Fresnel coefficient between the air and the medium. Aint/ = R = n- 1-,ɛ = 1+-R-= n2 Aair n +1 r 1- R Results : Internal layering is observed. The transition between dry sand and permafrost can be detected. The permittivity can be retrieved from delay or amplitude measurements as well from delay measurements : dry sand ɛr = 2.71 permafrost ɛr = 3.72 from amplitude measurements : dry sand ɛr = 2.73 permafrost ɛr = 3.35 Embedded objects are detected, Fracture and its orientation is detected

Shallow characterization of the subsurface for the 2018 Mission to Mars

The highest priority scientific objectives of the revised 2018 mission to Mars are (1) to search for evidence of past or present life, (2) to identify the samples that are most likely to preserve potential evidence of life and the nature of the early Martian environment that might have given rise to it and (3) to cache them for later retrieval back to Earth for more detailed analyses than can be performed by the rover's onboard analytical laboratory. WISDOM is a ground penetrating radar that has been designed to investigate the near subsurface of Mars down to a depth of ~2-3 m, with a vertical resolution of several centimeters - commensurate with the sampling capabilities of the ExoMars onboard drill. The ability of WISDOM to investigate the geology of the landing site in 3-dimensions will permit direct correlations between subsurface layers and horizons with those exposed in nearby outcrops and the interior of impact craters. By combining periodic soundings conducted during a Rover traverse with targeted, high density grid-type soundings of areas of potential scientific interest, it will be possible to construct a 3-dimensional map of the local radar stratigraphy. Of all of the Pasteur Payload instruments, only WISDOM has the ability to investigate and characterize the nature of the subsurface remotely. Moreover, the geoelectrical properties of H2O make WISDOM a powerful tool to understand the local distribution and state of subsurface H2O, including the potential presence of segregated ground ice and the persistent or transient occurrence of liquid water/brine. A WISDOM prototype, representative of the final flight model is now being tested. A series of calibrations and verifications have been initiated. The real performance of the instrument is currently assessed for various test environments. Results about the resolution and sensitivity achieved are presented as well as 3D representations of detected subsurface structures. Preliminary estimates of permittivity values are also shown

Wisdom GPR measurements in a cold artificial and controlled environment

International audienceThe WISDOM (500MHz - 3GHz) GPR is one of the instruments that have been selected as part of the Pasteur payload of ESA's 2018 ExoMars Rover mission. One of the main scientific objectives of the mission is to characterize the nature of the shallow sub-surface on Mars and WISDOM has been designed to explore the first ∼ 3 meters of the sub-surface with a vertical resolution of a few centimetres. In order to illustrate and quantify the WISDOM performance, measurements in cold artificial and controlled conditions have been performed by the prototype. The objectives of this experiment were the detection of home made internal layering and the possible detection of a wedge included in the permafrost filled with different material with known characteristics. Some results and comparisons with a simple simulation are presented here and show the WISDOM performances

WISDOM GPR investigations in a Mars-analog environment during the SAFER rover operation simulation

International audienceThe WISDOM (Water Ice Subsurface Deposits Observations on Mars) Ground Penetrating Radar has been selected to be onboard the ExoMars 2018 rover mission [1]. This instrument will investigate the Martian shallow subsurface and provide the geological context of the mission, by characterizing the subsurface in terms of structure, stratigraphy and potential buried objects. It will also quantify the geoelectrical properties of the medium, which are directly related to its nature, its water or salts content and its hardness [2]. WISDOM data will provide important clues to guide the drilling operations to location of potential exobiological interest. A prototype available in LATMOS, France, is currently tested in a wide range of natural environments. In this context, the WISDOM team participated in the SAFER (Sample Acquisition Field Experiment with a Rover) field trial that occurred from 7th to 13th October 2013 in the Atacama Desert, Chile. Designed to gather together scientists and engineers in a context of a real Martian mission with a rover, the SAFER trial was the opportunity to use three on-board ExoMars instruments, namely CLUPI (Close-UP Imager), PANCAM (Panoramic Camera) and WISDOM, to investigate the chosen area. We present the results derived from WISDOM data acquired over the SAFER trial site to characterize the shallow subsurface of the area

WISDOM GPR subsurface investigations in the Atacama desert during the SAFER rover operation simulation

SAFER (Sample Acquisition Field Experiment with a Rover) is a field trial that occured from 7th to 13th October 2013 in the Atacama desert, Chile. This trial was designed to gather together scientists and engineers in a context of a real spatial mission with a rover. This is ESA's opportunity to validate operations procedures for the ExoMars 2018 mission, since a rover, provided by Astrium, was equipped with three ExoMars payload instruments, namely the WISDOM (Water Ice Subsurface Deposits Observations on Mars) Ground Penetrating Radar, PANCAM (Panoramic Camera) and CLUPI (Close-UP Imager), and was used to experiment the real context of a Martian rover mission. The test site was located close to the Paranal ESO's Observatory (European Southern Observatorys) while the operations were conducted in the Satellite Applications Catapult remote Center in Harwell, UK. The location was chosen for its well-known resemblance with Mars' surface and its arid dryness. To provide the best from this trial, geologists, engineers and instrumentation scientists teams collaborated by processing and analyzing the data, planning in real time the next trajectories for the Bridget rover, as well as the sites of interest for WISDOM subsurface investigations. This WISDOM GPR has been designed to define the geological context of the ExoMars 2018 landing site by characterizing the shallow subsurface in terms of electromagnetic properties and structures. It will allow to lead the drill to locations of potential exobiologocal interest. WISDOM is a polarimetric step frequency radar operating from 0.5GHz to 3GHz, which allows a vertical resolution of a few centimeters over a few meters depth. Provided with a DEM (Digital Elevation Model) and a low-resolution map to assist the team with the rover's operations, several soudings with WISDOM were done over the area. The WISDOM data allowed, in collaboration with the SCISCYS team, to map the electromagnetic contrasts into the subsurface underneath the rover path and to get a 3D representation. WISDOM data were also used to assess the most promising locations for drilling operations by identifying the interfaces and the scatterers embedded in the subsurface and retrieving their depths. We present the results derived from WISDOM data acquired over the SAFER trial site to characterize the shallow subsurface of the area in terms of geology and electromagnetic properties. The quantitative results are compared with the characteristics of the samples removed from the site during drilling operations. The SAFER team carries on the cooperation in order to take the best from all instruments put together

WISDOM GPR Investigations of Ice Thickness, Stratigraphy, Structure and Basal Topography in an Alpine Ice Cave in Dachstein, Austria

Prototypes of the WISDOM GPR designed for the ExoMars rover mission have been tested in an ice cave.The experimental results show the instrument performance

Detection of sand grains blown by Titan surface winds with the DraGMet/EFIELD sensor on Dragonfly

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