Since their arrival at comet 67P in August 2014, a number of instruments onboard Rosetta’s main s... more Since their arrival at comet 67P in August 2014, a number of instruments onboard Rosetta’s main spacecraft and Philae lander have been observing the surface of the nucleus and revealed details of amazing surficial structures (hundreds of meters deep pits and cliffs, surface roughness of the order of a couple of meters in size, non-continuous apparent layers on both lobes of the comet). After two years of observations, the activity of the comet has also been better constrained, while the origin of sporadic jet activities remains debated. This surficial information is complemented by relevant measurements assessing the nucleus internal structure that have been collected by the CONSERT (Comet Nucleus Sounding Experiment by Radiowave Transmission) experiment in order to constrain the nucleus formation and evolution. The CONSERT experiment is a bistatic radar with receivers and transmitters on-board both Rosetta’s main spacecraft and the Philae lander. The instrument transmits electromag...
The Rosetta space mission included three main instruments for solid dust particle analysis. The c... more The Rosetta space mission included three main instruments for solid dust particle analysis. The combined microscope and mass spectrometer COSIMA (Cometary Secondary Ion Mass Analyser) [1], the atomic force microscope MIDAS (Micro-Imaging Dust Analysis System) [2], and the impact detector GIADA (Grain Impact Analyser and Dust Accumulator) [3]. These three instruments provide complementary insights into dust particles properties over a wide range of sizes/masses (10nm to 1mm). GIADA and MIDAS observed a major contribution from compact dust particles together with a population of porous particles with a low fractal dimension (Df~1,7 for MIDAS [4]) [5, 6]. The fractal dust component of the nucleus and its properties give constraints on the formation of comets in the early solar system [5]. In this work, we analyseresults from a simple numerical model of dust aggregates compactionto assess the initial physical properties of the dust populations.
<p>The Mars 2020 “Perseverance” rover&a... more <p>The Mars 2020 “Perseverance” rover’s SuperCam instrument suite [1,2,3] provides a wide variety of active and passive remote sensing techniques [4, 5, 6, 7] including passive visible & near-infrared (“VISIR”) spectroscopy [8]. Here we present our plans to use the VISIR technique for atmospheric science by observing solar radiation scattered by the Martian sky, similar to the “passive sky” technique demonstrated with ChemCam on the Mars Science Laboratory (MSL) rover [9]. Our presentation will focus on the objectives and techniques of SuperCam VISIR atmospheric science, but we will also present initial atmospheric science results or relevant instrument performance validation results to the extent that such are available at the time of the conference.</p><p>The objectives of VISIR atmospheric science are O<sub>2</sub>, CO, and H<sub>2</sub>O vapor column abundances, and aerosol particle sizes and composition. These objectives are motivated by unexpected seasonal and interannual variability in the O<sub>2</sub>mixing ratio that is argued to be so large as to require O<sub>2</sub> sources and sinks in surface soils [10], by evidence of surface-atmosphere exchange of H<sub>2</sub>O [11], by the potential significance of O<sub>2</sub> and H<sub>2</sub>O volatiles as field context for returned samples due to their active exchanges with surface materials, and by the Mars 2020 mission [12] objectives of characterizing dust and validating global atmospheric models to prepare for human exploration</p><p>The SuperCam spectrometers used for VISIR mode are a ChemCam-heritage reflection spectrometer covering 385–465 nm with < 0.2 nm res. [2], an intensified transmission spectrometer covering 536–853 nm with 0.3–0.7 nm res. [2], and an acousto-optic-tunable-filter (AOTF) -based IR spectrometer covering 1300–2600 nm with 20–30 cm<sup>-1</sup> res. [1, 8]. Our primary observing strategy is the same approach used for MSL ChemCam “passive sky” observations [9]: ratioing instrument signals from the two pointing positions with different elevation angles eliminates solar spectrum and instrument response uncertainties that are ~100x and ~10x larger than signals of interest for the transmission and AOTF IR spectrometers, respectively. We will also make use of single pointings directed at the white SuperCam calibration target for less-resource-intensive water vapor and aerosol monitoring, and of multiple-pointing lower-signal-to-noise sky scans to better constrain aerosol size and shape. <strong>Sky radiance is fit</strong><strong> </strong><strong>with a </strong><strong>discrete ordinates multiple scattering radiative transfer model</strong><strong> identical to that of [9].</strong><strong> As in [</strong><strong>9</strong><strong>] gas abundances are made robust to aerosol scattering uncertainties by fitting </strong>CO<sub>2</sub> absorption bands with an aerosol vertical profile parameter.</p><p>References: [1] Maurice S. et al. (2020) SSR, in press. [2] Wiens R.C. et al. (2021) SSR 217, 4. [3] Manrique J.-A. et al. (2020) SSR 216, 138. [4] Ollila A.M. et al. (2021), this meeting. [5] Ollila A.M. et al. (2018) LPSC 49, 2786. [6] Forni O. et al. (2021), this meeting. [7] Lanza N. L. et al. (2021), this meeting. [8] Johnson J.R et al. (2021), this meeting. [9] McConnochie T.H et al. (2018), Icarus 307, 294. [10] Trainer M.G. et al. (2019), JGR 124, 3000. [11] Savijärvi H. et al. (2016), Icarus 265, 63. [12] Farley K.A. et al. (2020), SSR 216, 142.</p>
Our purpose is to use CONSERT (Comet Nucleus Sounding Experiment by Radiowave Transmission) data ... more Our purpose is to use CONSERT (Comet Nucleus Sounding Experiment by Radiowave Transmission) data to provide information (at least constraints) about the heterogeneities inside the nucleus at spatial scales up to 10 meters and thus to contribute to a better understanding of the comet formation process.
B. Chide 1,2 , N. L. Lanza 3 , C. Alvarez 4 , S. M. Angel 5 , P. Bernardi 6 , O. Beyssac 7 , B. B... more B. Chide 1,2 , N. L. Lanza 3 , C. Alvarez 4 , S. M. Angel 5 , P. Bernardi 6 , O. Beyssac 7 , B. Bousquet 8 , A. Cadu 1 , E. Clavé 8 , O. Forni 2 , T. Fouchet 6 , O. Gasnault 2 , X. Jacob 9 , G. Lacombes 2 , J. Laserna 4 , J. Lasue 2 , R.D. Lorenz 10 , P.-Y. Meslin 2 , F. Montmessin 11 , J. Moros 4 , N. Murdoch 1 , A. M. Ollila 3 , P. Pilleri 2 , P. Purohit 4 , A. L. Reyes-Newell 3 , S. Schröder 12 , A. Stott 1 , D. Vogt 12 , S. Maurice 2 , R. C. Wiens 3 and D. Mimoun 1 . 1 ISAE-SUPAERO, Toulouse, France, 2 IRAPCNRS, Toulouse, France, 3 Los Alamos National Laboratory, NM, USA, 4 Universidad de Malaga, Malaga, Spain, 5 University of South Carolina, SC, USA, 6 LESIA, Meudon, France, 7 IMPMC, Paris, France, 8 CELIA, Bordeaux, France, 9 IMFT, Toulouse, France, 10 APL, MD, USA, 11 LATMOS, Guyancourt, France, 12 DLR, Berlin, Germany (baptiste.chide@irap.omp.eu)
In-situ observation of several comets by spacecraft, the collection and delivery to Earth of dust... more In-situ observation of several comets by spacecraft, the collection and delivery to Earth of dust from a cometary coma, remote sensing of comets, and comparison with the properties of interplanetary dust, some of which is cometary, collected at Earth, have provided many new insights to the composition and structure of cometary dust. These investigations have raised new, more detailed questions, suggesting future directions for comet research.
As chartered by the Science Definition Team, the Mars 2020 mission addresses four primary objecti... more As chartered by the Science Definition Team, the Mars 2020 mission addresses four primary objectives: A. Characterize the processes that formed and modified the geologic record within an astrobiologically relevant ancient environment, B. Perform astrobiologically relevant investigations to determine habitability, search for materials with biosignature presentation potential, and search for evidence of past life, C. Assemble a returnable cache of samples and D. Contribute to preparation for human exploration of Mars. The SuperCam instrument, selected for the Mars 2020 rover, as a suite of four instruments, provides nested and co-aligned remote investigations: Laser Induced Breakdown Spectroscopy (LIBS), Raman spectroscopy and time-resolved fluorescence (TRF), visible and near-infrared spectroscopy (VISIR), and high resolution color imaging (RMI). SuperCam appeals broadly to the four Mars 2020 objectives.In detail, SuperCam will perform:1. Microscale mineral identification by combinin...
Physical properties of dust in cometary comae have first been approached through unique flyby mis... more Physical properties of dust in cometary comae have first been approached through unique flyby missions and numerous remote observations of the intensity and polarization of the solar light they scatter. Clues to size distribution, morphology, refractive index of dust particles, and to their variations within comae have been derived from polarimetric data. The Rosetta rendezvous mission to 67P/Churyumov- Gerasimenko (hereafter 67P) is now confirming previous estimations and providing detailed evidence about the dust physical properties, through sophisticated measurements obtained in different regions of the coma and for different solar distances.
SuperCam is a multi-functional instrument on the Mars 2020 rover. It will conduct LIBS, Raman, VI... more SuperCam is a multi-functional instrument on the Mars 2020 rover. It will conduct LIBS, Raman, VISIR, luminescence, imaging, and acoustic analyses of the martian surface. Here, we demonstrate the synergy between these techniques.
Since the arrival of Rosetta at comet 67P, numerous pictures have been delivered by the cameras o... more Since the arrival of Rosetta at comet 67P, numerous pictures have been delivered by the cameras onboard both the main spacecraft and the Philae lander. They revealed, at the nucleus' surface and inside the walls of the deep pits, few-meters scale repeating structures, thus providing hints about the internal structure of the nucleus, and suggesting that primordial 'cometesimals' may be objects around 3m in size. The CONSERT (Comet Nucleus Sounding Experiment by Radiowave Transmission) experiment is a radar that has been designed to specifically sound the interior of the nucleus and to provide information on the nucleus internal structure. The work presented here is based on the CONSERT data collected during the First Science Sequence (FSS) and marginally during Philae’s Separation Descent and Landing (SDL) for comparison. During FFS, the smaller lobe of the nucleus in the vicinity of Abydos has been actually sounded by CONSERT’s electromagnetic waves at 90 MHz with a spat...
While amazing surface features of comet 67P have been observed and revealed since the beginning o... more While amazing surface features of comet 67P have been observed and revealed since the beginning of the Rosetta mission by a number of cameras onboard Rosetta’s main spacecraft (OSIRIS and NAVCAM) and Philae lander (CIVA and ROLIS), information below the surface has also been collected by the CONSERT (Comet Nucleus Sounding Experiment by Radiowave Transmission) experiment that can help constrain the nucleus formation and evolution. CONSERT is a bistatic radar with receivers and transmitters on-board both Rosetta’s main spacecraft and Philae lander. It has been successfully operating during the descent and First Science Sequence (FSS) right after Philae’s final landing at Abydos. The nucleus in the vicinity of Abydos has been actually sounded by CONSERT’s electromagnetic waves at 90 MHz with a spatial resolution around 10m (over lengths ranging from approximately 200 to 800 m and maximum depths of about one hundred of meters). The data collected provide information about the permittiv...
The structure of the nucleus is one of major unknown in the cometary science. The scientific obje... more The structure of the nucleus is one of major unknown in the cometary science. The scientific objectives of the Comet Nucleus Sounding Experiment by Radiowave Transmission (CONSERT) aboard ESA spacecraft Rosetta are to perform an interior characterization of comet 67P/Churyumov-Gerasimenko nucleus. This is done by means of a bi-static sounding between the lander Philae launched on the comet’s surface and the obiter Rosetta. During the first night after Philae landing CONSERT operated during 9 hours and have made the measurements through the small lobe (head) of the 67P/ C-G. We will describe measurements that explored the interior of the comet, discuss results and their interpretation in term of the internal structure. The analyses and interpretation have been done using the form of the received signals and then 2D and 3D modelling of the signal that propagated through the comet. This led us to conclusions that the comet is homogenous on the scale of the ten of wavelengths and perhap...
Since the arrival of the Rosetta spacecraft at comet 67P/Churyumov-Gerasimenko in August 2014, a ... more Since the arrival of the Rosetta spacecraft at comet 67P/Churyumov-Gerasimenko in August 2014, a series of instruments have been observing the surface of the nucleus at distances ranging from more than 10 000 km down to less than one meter. The cameras onboard the Rosetta's main spacecraft (NAVCAM [1], OSIRIS [2]) and Philae lander (CIVA [3], ROLIS [4]) have revealed details of amazing structures giving some very partial hints about the internal structure of the nucleus. This is the case for the a few hundreds-of-meters deep pits [5] linked to the comet's activity; and the layers and terraces [6, 7, 8] revealed by the OSIRIS images. The CONSERT (Comet Nucleus Sounding Experiment by Radiowave Transmission) experiment [9] has been specifically designed to sound the interior of the nucleus and provide information on the nucleus structure at depth. The work presented here is based on the CONSERT data collected during the First Science Sequence and aims at constraining the small ...
Since their arrival at comet 67P in August 2014, a number of instruments onboard Rosetta’s main s... more Since their arrival at comet 67P in August 2014, a number of instruments onboard Rosetta’s main spacecraft and Philae lander have been observing the surface of the nucleus and have revealed details of amazing structures. This information was complemented by information about the nucleus internal structure collected by the CONSERT (Comet Nucleus Sounding Experiment by Radiowave Transmission) experiment in order to constrain the nucleus formation and evolution. The CONSERT experiment is a bistatic radar with receivers and transmitters on-board both Rosetta’s main spacecraft and Philae lander. The instrument makes use of electromagnetic waves at 90 MHz that propagated, during the First Science Sequence, between Philae and Rosetta through the small lobe of 67P over distances ranging from approximately 200 to 800 m depending on the spacecraft location. The data used here have been collected at depths that reach a maximum of about one hundred of meters nucleus in the vicinity of Abydos. T...
Various approaches have progressively suggested that a significant fraction of dust particles in ... more Various approaches have progressively suggested that a significant fraction of dust particles in the interplanetary dust cloud (i.e., zodiacal cloud), which enter the Earth atmosphere and suffer ablation [1], may originate from Jupiter Family Comets [2-5]. These particles had been ejected from the nuclei of active comets, and had formed meteoroid streams and (for the largest fragments) cometary dust trails. The Rosetta mission to comet 67P/Churyumov-Gerasimenko (67P), togetherwith remote observations of comets and their interpretation, may thus provide clues to the physical properties of meteoroids and micrometeorites.Main results on cometary dust properties, as reviewed with emphasis on 67P [6], establish i) that the refractory organic phase in cometary dust is dominated by complex organic compounds, meaning that comets are an important reservoir of carbon and organic matter, ii) that the dust particles are aggregates of grains presenting a hierarchical structure, with morphologies...
Numerous polarimetric observations of solar light scattered by dust in cometary comae have been o... more Numerous polarimetric observations of solar light scattered by dust in cometary comae have been obtained by various teams, providing phase angle and wavelength dependences for many comets and revealing different classes of comets [e.g., 1]. Besides, numerical and experimental simulations have suggested interpretations for such observations. The Rosetta long duration rendezvous with comet 67P/Churyumov-Gerasimenko (thereafter 67P/C-G) now allows us to compare our understanding of the polarimetric properties of cometary dust with the ground-truth provided by the Rosetta mission, at least for two typical results. First, some comets present a highly-polarized positive branch, the most conspicuous case being that of new comet C/1995 O1 Hale-Bopp [2], while other comets suffering a partial fragmentation or a total disruption, such as C/1995 S4 LINEAR [3], present a significant increase in polarization. We will discuss these observations in the context of evidence for changes between the p...
Since their arrival at comet 67P in August 2014, a number of instruments onboard Rosetta’s main s... more Since their arrival at comet 67P in August 2014, a number of instruments onboard Rosetta’s main spacecraft and Philae lander have been observing the surface of the nucleus and revealed details of amazing surficial structures (hundreds of meters deep pits and cliffs, surface roughness of the order of a couple of meters in size, non-continuous apparent layers on both lobes of the comet). After two years of observations, the activity of the comet has also been better constrained, while the origin of sporadic jet activities remains debated. This surficial information is complemented by relevant measurements assessing the nucleus internal structure that have been collected by the CONSERT (Comet Nucleus Sounding Experiment by Radiowave Transmission) experiment in order to constrain the nucleus formation and evolution. The CONSERT experiment is a bistatic radar with receivers and transmitters on-board both Rosetta’s main spacecraft and the Philae lander. The instrument transmits electromag...
The Rosetta space mission included three main instruments for solid dust particle analysis. The c... more The Rosetta space mission included three main instruments for solid dust particle analysis. The combined microscope and mass spectrometer COSIMA (Cometary Secondary Ion Mass Analyser) [1], the atomic force microscope MIDAS (Micro-Imaging Dust Analysis System) [2], and the impact detector GIADA (Grain Impact Analyser and Dust Accumulator) [3]. These three instruments provide complementary insights into dust particles properties over a wide range of sizes/masses (10nm to 1mm). GIADA and MIDAS observed a major contribution from compact dust particles together with a population of porous particles with a low fractal dimension (Df~1,7 for MIDAS [4]) [5, 6]. The fractal dust component of the nucleus and its properties give constraints on the formation of comets in the early solar system [5]. In this work, we analyseresults from a simple numerical model of dust aggregates compactionto assess the initial physical properties of the dust populations.
<p>The Mars 2020 “Perseverance” rover&a... more <p>The Mars 2020 “Perseverance” rover’s SuperCam instrument suite [1,2,3] provides a wide variety of active and passive remote sensing techniques [4, 5, 6, 7] including passive visible & near-infrared (“VISIR”) spectroscopy [8]. Here we present our plans to use the VISIR technique for atmospheric science by observing solar radiation scattered by the Martian sky, similar to the “passive sky” technique demonstrated with ChemCam on the Mars Science Laboratory (MSL) rover [9]. Our presentation will focus on the objectives and techniques of SuperCam VISIR atmospheric science, but we will also present initial atmospheric science results or relevant instrument performance validation results to the extent that such are available at the time of the conference.</p><p>The objectives of VISIR atmospheric science are O<sub>2</sub>, CO, and H<sub>2</sub>O vapor column abundances, and aerosol particle sizes and composition. These objectives are motivated by unexpected seasonal and interannual variability in the O<sub>2</sub>mixing ratio that is argued to be so large as to require O<sub>2</sub> sources and sinks in surface soils [10], by evidence of surface-atmosphere exchange of H<sub>2</sub>O [11], by the potential significance of O<sub>2</sub> and H<sub>2</sub>O volatiles as field context for returned samples due to their active exchanges with surface materials, and by the Mars 2020 mission [12] objectives of characterizing dust and validating global atmospheric models to prepare for human exploration</p><p>The SuperCam spectrometers used for VISIR mode are a ChemCam-heritage reflection spectrometer covering 385–465 nm with < 0.2 nm res. [2], an intensified transmission spectrometer covering 536–853 nm with 0.3–0.7 nm res. [2], and an acousto-optic-tunable-filter (AOTF) -based IR spectrometer covering 1300–2600 nm with 20–30 cm<sup>-1</sup> res. [1, 8]. Our primary observing strategy is the same approach used for MSL ChemCam “passive sky” observations [9]: ratioing instrument signals from the two pointing positions with different elevation angles eliminates solar spectrum and instrument response uncertainties that are ~100x and ~10x larger than signals of interest for the transmission and AOTF IR spectrometers, respectively. We will also make use of single pointings directed at the white SuperCam calibration target for less-resource-intensive water vapor and aerosol monitoring, and of multiple-pointing lower-signal-to-noise sky scans to better constrain aerosol size and shape. <strong>Sky radiance is fit</strong><strong> </strong><strong>with a </strong><strong>discrete ordinates multiple scattering radiative transfer model</strong><strong> identical to that of [9].</strong><strong> As in [</strong><strong>9</strong><strong>] gas abundances are made robust to aerosol scattering uncertainties by fitting </strong>CO<sub>2</sub> absorption bands with an aerosol vertical profile parameter.</p><p>References: [1] Maurice S. et al. (2020) SSR, in press. [2] Wiens R.C. et al. (2021) SSR 217, 4. [3] Manrique J.-A. et al. (2020) SSR 216, 138. [4] Ollila A.M. et al. (2021), this meeting. [5] Ollila A.M. et al. (2018) LPSC 49, 2786. [6] Forni O. et al. (2021), this meeting. [7] Lanza N. L. et al. (2021), this meeting. [8] Johnson J.R et al. (2021), this meeting. [9] McConnochie T.H et al. (2018), Icarus 307, 294. [10] Trainer M.G. et al. (2019), JGR 124, 3000. [11] Savijärvi H. et al. (2016), Icarus 265, 63. [12] Farley K.A. et al. (2020), SSR 216, 142.</p>
Our purpose is to use CONSERT (Comet Nucleus Sounding Experiment by Radiowave Transmission) data ... more Our purpose is to use CONSERT (Comet Nucleus Sounding Experiment by Radiowave Transmission) data to provide information (at least constraints) about the heterogeneities inside the nucleus at spatial scales up to 10 meters and thus to contribute to a better understanding of the comet formation process.
B. Chide 1,2 , N. L. Lanza 3 , C. Alvarez 4 , S. M. Angel 5 , P. Bernardi 6 , O. Beyssac 7 , B. B... more B. Chide 1,2 , N. L. Lanza 3 , C. Alvarez 4 , S. M. Angel 5 , P. Bernardi 6 , O. Beyssac 7 , B. Bousquet 8 , A. Cadu 1 , E. Clavé 8 , O. Forni 2 , T. Fouchet 6 , O. Gasnault 2 , X. Jacob 9 , G. Lacombes 2 , J. Laserna 4 , J. Lasue 2 , R.D. Lorenz 10 , P.-Y. Meslin 2 , F. Montmessin 11 , J. Moros 4 , N. Murdoch 1 , A. M. Ollila 3 , P. Pilleri 2 , P. Purohit 4 , A. L. Reyes-Newell 3 , S. Schröder 12 , A. Stott 1 , D. Vogt 12 , S. Maurice 2 , R. C. Wiens 3 and D. Mimoun 1 . 1 ISAE-SUPAERO, Toulouse, France, 2 IRAPCNRS, Toulouse, France, 3 Los Alamos National Laboratory, NM, USA, 4 Universidad de Malaga, Malaga, Spain, 5 University of South Carolina, SC, USA, 6 LESIA, Meudon, France, 7 IMPMC, Paris, France, 8 CELIA, Bordeaux, France, 9 IMFT, Toulouse, France, 10 APL, MD, USA, 11 LATMOS, Guyancourt, France, 12 DLR, Berlin, Germany (baptiste.chide@irap.omp.eu)
In-situ observation of several comets by spacecraft, the collection and delivery to Earth of dust... more In-situ observation of several comets by spacecraft, the collection and delivery to Earth of dust from a cometary coma, remote sensing of comets, and comparison with the properties of interplanetary dust, some of which is cometary, collected at Earth, have provided many new insights to the composition and structure of cometary dust. These investigations have raised new, more detailed questions, suggesting future directions for comet research.
As chartered by the Science Definition Team, the Mars 2020 mission addresses four primary objecti... more As chartered by the Science Definition Team, the Mars 2020 mission addresses four primary objectives: A. Characterize the processes that formed and modified the geologic record within an astrobiologically relevant ancient environment, B. Perform astrobiologically relevant investigations to determine habitability, search for materials with biosignature presentation potential, and search for evidence of past life, C. Assemble a returnable cache of samples and D. Contribute to preparation for human exploration of Mars. The SuperCam instrument, selected for the Mars 2020 rover, as a suite of four instruments, provides nested and co-aligned remote investigations: Laser Induced Breakdown Spectroscopy (LIBS), Raman spectroscopy and time-resolved fluorescence (TRF), visible and near-infrared spectroscopy (VISIR), and high resolution color imaging (RMI). SuperCam appeals broadly to the four Mars 2020 objectives.In detail, SuperCam will perform:1. Microscale mineral identification by combinin...
Physical properties of dust in cometary comae have first been approached through unique flyby mis... more Physical properties of dust in cometary comae have first been approached through unique flyby missions and numerous remote observations of the intensity and polarization of the solar light they scatter. Clues to size distribution, morphology, refractive index of dust particles, and to their variations within comae have been derived from polarimetric data. The Rosetta rendezvous mission to 67P/Churyumov- Gerasimenko (hereafter 67P) is now confirming previous estimations and providing detailed evidence about the dust physical properties, through sophisticated measurements obtained in different regions of the coma and for different solar distances.
SuperCam is a multi-functional instrument on the Mars 2020 rover. It will conduct LIBS, Raman, VI... more SuperCam is a multi-functional instrument on the Mars 2020 rover. It will conduct LIBS, Raman, VISIR, luminescence, imaging, and acoustic analyses of the martian surface. Here, we demonstrate the synergy between these techniques.
Since the arrival of Rosetta at comet 67P, numerous pictures have been delivered by the cameras o... more Since the arrival of Rosetta at comet 67P, numerous pictures have been delivered by the cameras onboard both the main spacecraft and the Philae lander. They revealed, at the nucleus' surface and inside the walls of the deep pits, few-meters scale repeating structures, thus providing hints about the internal structure of the nucleus, and suggesting that primordial 'cometesimals' may be objects around 3m in size. The CONSERT (Comet Nucleus Sounding Experiment by Radiowave Transmission) experiment is a radar that has been designed to specifically sound the interior of the nucleus and to provide information on the nucleus internal structure. The work presented here is based on the CONSERT data collected during the First Science Sequence (FSS) and marginally during Philae’s Separation Descent and Landing (SDL) for comparison. During FFS, the smaller lobe of the nucleus in the vicinity of Abydos has been actually sounded by CONSERT’s electromagnetic waves at 90 MHz with a spat...
While amazing surface features of comet 67P have been observed and revealed since the beginning o... more While amazing surface features of comet 67P have been observed and revealed since the beginning of the Rosetta mission by a number of cameras onboard Rosetta’s main spacecraft (OSIRIS and NAVCAM) and Philae lander (CIVA and ROLIS), information below the surface has also been collected by the CONSERT (Comet Nucleus Sounding Experiment by Radiowave Transmission) experiment that can help constrain the nucleus formation and evolution. CONSERT is a bistatic radar with receivers and transmitters on-board both Rosetta’s main spacecraft and Philae lander. It has been successfully operating during the descent and First Science Sequence (FSS) right after Philae’s final landing at Abydos. The nucleus in the vicinity of Abydos has been actually sounded by CONSERT’s electromagnetic waves at 90 MHz with a spatial resolution around 10m (over lengths ranging from approximately 200 to 800 m and maximum depths of about one hundred of meters). The data collected provide information about the permittiv...
The structure of the nucleus is one of major unknown in the cometary science. The scientific obje... more The structure of the nucleus is one of major unknown in the cometary science. The scientific objectives of the Comet Nucleus Sounding Experiment by Radiowave Transmission (CONSERT) aboard ESA spacecraft Rosetta are to perform an interior characterization of comet 67P/Churyumov-Gerasimenko nucleus. This is done by means of a bi-static sounding between the lander Philae launched on the comet’s surface and the obiter Rosetta. During the first night after Philae landing CONSERT operated during 9 hours and have made the measurements through the small lobe (head) of the 67P/ C-G. We will describe measurements that explored the interior of the comet, discuss results and their interpretation in term of the internal structure. The analyses and interpretation have been done using the form of the received signals and then 2D and 3D modelling of the signal that propagated through the comet. This led us to conclusions that the comet is homogenous on the scale of the ten of wavelengths and perhap...
Since the arrival of the Rosetta spacecraft at comet 67P/Churyumov-Gerasimenko in August 2014, a ... more Since the arrival of the Rosetta spacecraft at comet 67P/Churyumov-Gerasimenko in August 2014, a series of instruments have been observing the surface of the nucleus at distances ranging from more than 10 000 km down to less than one meter. The cameras onboard the Rosetta's main spacecraft (NAVCAM [1], OSIRIS [2]) and Philae lander (CIVA [3], ROLIS [4]) have revealed details of amazing structures giving some very partial hints about the internal structure of the nucleus. This is the case for the a few hundreds-of-meters deep pits [5] linked to the comet's activity; and the layers and terraces [6, 7, 8] revealed by the OSIRIS images. The CONSERT (Comet Nucleus Sounding Experiment by Radiowave Transmission) experiment [9] has been specifically designed to sound the interior of the nucleus and provide information on the nucleus structure at depth. The work presented here is based on the CONSERT data collected during the First Science Sequence and aims at constraining the small ...
Since their arrival at comet 67P in August 2014, a number of instruments onboard Rosetta’s main s... more Since their arrival at comet 67P in August 2014, a number of instruments onboard Rosetta’s main spacecraft and Philae lander have been observing the surface of the nucleus and have revealed details of amazing structures. This information was complemented by information about the nucleus internal structure collected by the CONSERT (Comet Nucleus Sounding Experiment by Radiowave Transmission) experiment in order to constrain the nucleus formation and evolution. The CONSERT experiment is a bistatic radar with receivers and transmitters on-board both Rosetta’s main spacecraft and Philae lander. The instrument makes use of electromagnetic waves at 90 MHz that propagated, during the First Science Sequence, between Philae and Rosetta through the small lobe of 67P over distances ranging from approximately 200 to 800 m depending on the spacecraft location. The data used here have been collected at depths that reach a maximum of about one hundred of meters nucleus in the vicinity of Abydos. T...
Various approaches have progressively suggested that a significant fraction of dust particles in ... more Various approaches have progressively suggested that a significant fraction of dust particles in the interplanetary dust cloud (i.e., zodiacal cloud), which enter the Earth atmosphere and suffer ablation [1], may originate from Jupiter Family Comets [2-5]. These particles had been ejected from the nuclei of active comets, and had formed meteoroid streams and (for the largest fragments) cometary dust trails. The Rosetta mission to comet 67P/Churyumov-Gerasimenko (67P), togetherwith remote observations of comets and their interpretation, may thus provide clues to the physical properties of meteoroids and micrometeorites.Main results on cometary dust properties, as reviewed with emphasis on 67P [6], establish i) that the refractory organic phase in cometary dust is dominated by complex organic compounds, meaning that comets are an important reservoir of carbon and organic matter, ii) that the dust particles are aggregates of grains presenting a hierarchical structure, with morphologies...
Numerous polarimetric observations of solar light scattered by dust in cometary comae have been o... more Numerous polarimetric observations of solar light scattered by dust in cometary comae have been obtained by various teams, providing phase angle and wavelength dependences for many comets and revealing different classes of comets [e.g., 1]. Besides, numerical and experimental simulations have suggested interpretations for such observations. The Rosetta long duration rendezvous with comet 67P/Churyumov-Gerasimenko (thereafter 67P/C-G) now allows us to compare our understanding of the polarimetric properties of cometary dust with the ground-truth provided by the Rosetta mission, at least for two typical results. First, some comets present a highly-polarized positive branch, the most conspicuous case being that of new comet C/1995 O1 Hale-Bopp [2], while other comets suffering a partial fragmentation or a total disruption, such as C/1995 S4 LINEAR [3], present a significant increase in polarization. We will discuss these observations in the context of evidence for changes between the p...
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