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]

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

Eight years of solar observations with PICARD

International audiencePICARD is a mission devoted to solar variability observation, which aims at perpetuating valuable historical time-series of the solar radius. PICARD contains a double program with in-space and on-ground measurements using Ritchey-Chrétien telescopes. The PICARD spacecraft was launched on June 15, 2010, commissioned in-flight in October of the same year, and was retired in April 2014. PICARD ground-based observatory is functional since May 2011 in the Plateau de Calern (France), and is still operational today. We shall give an overview of the PICARD instrumentation and the performances of the existing ground-based telescope. We will also present our current results about solar radius variations after eight years of solar observations

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

Characterization and performances of the WISDOM ground penetrating radar for the ExoMars 2020 mission

International audienceIn this paper, we present the results of the tests and characterizations performed on the WISDOM/ExoMars 2020 radar that has been delivered for integration on the Rosalind Franklin mission rover. While the impact of the rover will be determined after a dedicated series of measurements performed at Airbus’s premises in Stevenage, reference measurements (in free-space and with specific targets) have been acquired and are currently taken into account in the data processing pipeline.Calibrated data are obtained that make possible a quantitative analysis of the amplitude of the received signals, especially of the surface echo, which is used to get an estimate of the permittivity value in the subsurface top layer. Results on the achieved vertical resolution will be presented too

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

Shallow subsurface sounding from a rover with a polarimetric GPR

The WISDOM GPR has been designed, for the ExoMars 2018 ESA mission, to investigate the Martian near subsurface down to a depth of a few meters with a vertical resolution of a few centimeters. 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. The work presented focuses on the capacities provided by these polarimetric measurement

The Space instrument SODISM of the PICARD mission

International audiencePICARD is a French space scientific mission. Its objectives are the study of the origin of the solar variability and the study of the relations between the Sun and the Earth's climate. The launch is foreseen by the end of 2009 on a Sun Synchronous Orbit at 725 km altitude. The mission life time is two years, however to be extended to three years. The payload consists in two absolute radiometers measuring the TSI (Total Solar Irradiance) and an imaging telescope to determine the solar diameter, the limb shape and asphericity. SOVAP (SOlar VAriability PICARD) is an absolute radiometer provided by the RMIB (Royal Meteorological Institute of Belgium) to measure the TSI. It also carries a bolometer used for increasing the TSI sampling and ageing control. PREMOS (PREcision MOnitoring Sensor) radiometer is provided by the PMOD/WRC (Physikalisch-Meteorologisches Observatorium Davos / World Radiation Center) to measure the TSI and the Spectral Solar Irradiance. SODISM (SOlar DiameterImager and Surface Mapper), is an 11-cm Cassegrain imaging telescope developed at CNRS (Centre National de la Recherche Scientifique) by LATMOS (Laboratoire, ATmosphere, Milieux, Observations Spatiales) associated with a 2Kx2K CCD (Charge-Coupled Device), taking solar images at five wavelengths. It carries a four-prism system to ensure a metrological control of the optics magnification. SODISM allows us to measure the solar diameter and shape with an accuracy of a few milliarcseconds, and to perform helioseismologic observations to probe the solar interior. In this article, we describe the SODISM telescope and its thermoelastic properties. We also present the PICARD data and the PICARD ground instruments which will observe together with the space instrument

Getting Ready for Mars: WISDOM/ExoMars 2020 Data Processing Pipeline and Field Tests

International audienceIn this paper we describe the data processing pipeline we have developed in order to analyze the GPR WISDOM/ExoMars 2020 electromagnetic soundings and the results and lessons learnt from a recent simulation operation field campaign in Chile

The space instrument SODISM and the ground instrument SODISM II

International audiencePICARD is a French space scientific mission. Its objectives are the study of the origin of the solar variability and the study of the relations between the Sun and the Earth's climate. The launch is scheduled for 2010 on a Sun Synchronous Orbit at 725 km altitude. The mission lifetime is two years, however that can be extended to three years. The payload consists of two absolute radiometers measuring the TSI (Total Solar Irradiance) and an imaging telescope to determine the solar diameter, the limb shape and asphericity. SOVAP (SOlar VAriability PICARD) is an absolute radiometer provided by the RMIB (Royal Meteorological Institute of Belgium) to measure the TSI. It also carries a bolometer used for increasing the TSI sampling and ageing control. PREMOS (PREcision MOnitoring Sensor) radiometer is provided by the PMOD/WRC (Physikalisch Meteorologisches Observatorium of Davos / World Radiation Center) to measure the TSI and the Spectral Solar Irradiance. SODISM (SOlar Diameter Imager and Surface Mapper), is an 11-cm Ritchey-Chretien imaging telescope developed at CNRS (Centre National de la Recherche Scientifique) by LATMOS (Laboratoire, ATmosphere, Milieux, Observations Spatiales) ex Service d'Aeronomie, associated with a 2Kx2K CCD (Charge-Coupled Device), taking solar images at five wavelengths. It carries a four-prism system to ensure a metrological control of the optics magnification. SODISM allows us to measure the solar diameter and shape with an accuracy of a few milliarcseconds, and to perform helioseismologic observations to probe the solar interior. In this article, we describe the space instrument SODISM and its thermo-elastic properties. We also present the PICARD payload data center and the ground instrument SODISM II which will observe together with the space instrument