47 research outputs found
Etude en laboratoire de grains extraterrestres et de leurs analogues de synthĂšse
L Ă©tude en laboratoire de matĂ©riaux extraterrestres provenant d objets ayant peu ou pas Ă©voluĂ© depuis leur formation il y a environ 4.6 milliards d annĂ©es, peut amĂ©liorer notre connaissance sur les dĂ©buts de notre systĂšme planĂ©taire. Par ailleurs, la simulation en laboratoire de certains processus que ces matĂ©riaux sont susceptibles de subir au cours de leur histoire apporte Ă©galement de prĂ©cieuses informations pour l interprĂ©tation des donnĂ©es issues des observations astronomiques ainsi que pour la comprĂ©hension de l Ă©volution des solides du Milieu Interstellaire jusqu Ă leur incorporation dans des objets planĂ©taires, objets incluant aussi toutes sortes de dĂ©bris tels que les astĂ©roĂdes, les comĂštes et toutes sortes de poussiĂšres accessibles Ă la collecte et/ou Ă l observation.Au cours de cette thĂšse, l analyse des matĂ©riaux organiques ainsi que des matĂ©riaux silicatĂ©s, jusqu alors peu Ă©tudiĂ©s conjointement, dans les poussiĂšres stratosphĂ©riques d origine cosmique, rĂ©vĂšle une corrĂ©lation entre la minĂ©ralogie des grains et la longueur des chaĂźnes carbonĂ©es. Ce lien ne semble pas le fruit de processus Ă la surface des corps parents des grains mais semble plutĂŽt tracer des processus prĂ©-accrĂ©tionnels. La conservation de composants peu altĂ©rĂ©s sur les corps parents dans les matĂ©riaux extraterrestres est encore une fois confirmĂ©e par la dĂ©couverte, au cours de cette thĂšse, d inclusions dans la mĂ©tĂ©orite carbonĂ©e Paris dont les spectres infrarouges sont trĂšs similaires Ă ceux des composĂ©s carbonĂ©s observĂ©s dans le Milieu Interstellaire. L Ă©tude de grains comĂ©taires issus de la mission spatiale Stardust a montrĂ©, contrairement Ă l idĂ©e que les comĂštes soient composĂ©es uniquement de matĂ©riaux primitifs puisque conservĂ©s dans un rĂ©servoir froid, que celles-ci contiennent aussi un certain nombre de matĂ©riaux formĂ©s Ă haute tempĂ©rature, confirmant alors de prĂ©cĂ©dentes analyses d Ă©chantillons de Stardust et impliquant des Ă©changes de matĂ©riaux Ă grande Ă©chelle radiale dans le jeune SystĂšme solaire.La deuxiĂšme partie de ce travail, consacrĂ©e Ă l Ă©tude d analogues de matiĂšre extraterrestre, porte sur le rĂŽle qu ont pu jouer les matĂ©riaux Ă partir desquels les planĂštes telluriques se sont formĂ©es dans l apport de l eau sur la Terre dans le cadre du scĂ©nario dit de wet accretion . Les expĂ©riences effectuĂ©es au cours de cette thĂšse visant Ă simuler les interactions entre silicates et vapeur d eau ont montrĂ© que ces matĂ©riaux permettent de stocker d importantes quantitĂ©s d eau Ă leur surface par adsorption des molĂ©cules de la phase gazeuse.Laboratory analyses performed on extraterrestrial materials originating from primitive bodies of our Solar System, that are bodies known to have suffered low alteration since their formation 4.6 billion years ago, can improve our knowledge on processes that have occurred in the early phase of our planetary system. Furthermore, laboratory simulations of some processes that these materials are likely to suffer during their life cycle also bring precious indications for interpreting observational data as well as for understanding the evolution of solids from the Interstellar Medium to their incorporation into planetary bodies, these latter including asteroids, comets and all kinds of dust that may be observed and/or collected back to Earth.During this thesis, the analysis of silicate as well as organic materials, which have not been much studied jointly so far, in stratospheric particles of cosmic origin, reveals a correlation between the mineralogy of the grains and the lengths of the chains of their carbonaceous component. This link does not seem to be due to parent body processing but rather to trace pre-accretionnal processes. The preservation of pristine components in extraterrestrial materials slightly altered on their parent bodies is again confirmed by the discovery in this work, of inclusions in the Paris carbonaceous chondrite whose infrared spectra are similar to the interstellar carbonaceous species. The study of cometary grains from the Stardust space mission showed, unlike the common idea that comets should be composed only of primitive materials since they reside in a cold reservoir, that comets do also contain a number of materials formed at high temperature, thus confirming results from previous studies of Stardust samples and implying large-scale radial mixing of materials in the young Solar system disk.The second part of my work, dedicated to experiments on primitive extraterrestrial amorphous silicates analogs, is aimed to study the role that materials from which Earth has accreted could have played in its water budget in the frame of the wet accretion scenario. The experiments performed along this thesis simulating interactions between silicates and water vapor, showed that silicates allow the storage of large quantities of water by adsorption onto their surface of molecules directly from the gas phase.PARIS11-SCD-Bib. Ă©lectronique (914719901) / SudocSudocFranceF
The Morphological, Elastic, and Electric Properties of Dust Aggregates in Comets: A Close Look at COSIMA/Rosetta's Data on Dust in Comet 67P/Churyumov-Gerasimenko
The Cometary Secondary Ion Mass Analyzer (COSIMA) onboard ESA's Rosetta
orbiter has revealed that dust particles in the coma of Comet
67P/Churyumov-Gerasimenko are aggregates of small grains. We study the
morphological, elastic, and electric properties of dust aggregates in the coma
of Comet 67P/Churyumov-Gerasimenko using optical microscopic images taken by
the COSIMA instrument. Dust aggregates in COSIMA images are well represented as
fractals in harmony with morphological data from MIDAS (Micro-Imaging Dust
Analysis System) and GIADA (Grain Impact Analyzer and Dust Accumulator) onboard
Rosetta. COSIMA's images, together with the data from the other Rosetta's
instruments such as MIDAS and GIADA do not contradict the so-called rainout
growth of -sized particles in the solar nebula. The elastic
and electric properties of dust aggregates measured by COSIMA suggest that the
surface chemistry of cometary dust is well represented as carbonaceous matter
rather than silicates or ices, consistent with the mass spectra, and that
organic matter is to some extent carbonized by solar radiation, as inferred
from optical and infrared observations of various comets. Electrostatic lofting
of cometary dust by intense electric fields at the terminator of its parent
comet is unlikely, unless the surface chemistry of the dust changes from a
dielectric to a conductor. Our findings are not in conflict with our current
understanding of comet formation and evolution, which begin with the
accumulation of condensates in the solar nebula and follow with the formation
of a dust mantle in the inner solar system.Comment: 17 pages, 12 figures, 1 tables, to appear in Planetary and Space
Scienc
The detection of solid phosphorus and fluorine in the dust from the coma of comet 67P/Churyumov-Gerasimenko
Here, we report the detection of phosphorus and fluorine in solid
particles collected from the inner coma of comet
67P/Churyumov-Gerasimenko measured with the COmetary Secondary Ion Mass
Analyser (COSIMA) instrument on-board the Rosetta spacecraft, only a few
kilometers away from the comet nucleus. We have detected
phosphorus-containing minerals from the presented COSIMA mass spectra,
and can rule out e.g. apatite minerals as the source of phosphorus. This
result completes the detection of life-necessary CHNOPS-elements in
solid cometary matter, indicating cometary delivery as a potential
source of these elements to the young Earth. Fluorine was also detected
with CF+ secondary ions originating from the cometary dust. </p
Similarities in element âcontent between comet 67P/ChuryumovâGerasimenko coma dust and selected meteorite samples
We have analysed the element composition and the context of particles
collected within the coma of 67P/ChuryumovâGerasimenko with Rosettaâs
COmetary Secondary Ion Mass Analyzer (COSIMA). A comparison has been
made between on board cometary samples and four meteorite samples
measured in the laboratory with the COSIMA reference model. Focusing on
the rock-forming elements, we have found similarities with chondrite
meteorites for some ion count ratios. The composition of
67P/ChuryumovâGerasimenko particles measured by COSIMA shows an
enrichment in volatile elements compared to that of the investigated
Renazzo (CR2) carbonaceous meteorite sample.</p
COSIMA-Rosetta calibration for in-situ characterization of 67P/Churyumov-Gerasimenko cometary inorganic compounds
20 pages, 3 figures, 5 tablesInternational audienceCOSIMA (COmetary Secondary Ion Mass Analyser) is a time-of-flight secondary ion mass spectrometer (TOF-SIMS) on board the Rosetta space mission. COSIMA has been designed to measure the composition of cometary dust grains. It has a mass resolution m/{\Delta}m of 1400 at mass 100 u, thus enabling the discrimination of inorganic mass peaks from organic ones in the mass spectra. We have evaluated the identification capabilities of the reference model of COSIMA for inorganic compounds using a suite of terrestrial minerals that are relevant for cometary science. Ground calibration demonstrated that the performances of the flight model were similar to that of the reference model. The list of minerals used in this study was chosen based on the mineralogy of meteorites, interplanetary dust particles and Stardust samples. It contains anhydrous and hydrous ferromagnesian silicates, refractory silicates and oxides (present in meteoritic Ca-Al-rich inclusions), carbonates, and Fe-Ni sulfides. From the analyses of these minerals, we have calculated relative sensitivity factors for a suite of major and minor elements in order to provide a basis for element quantification for the possible identification of major mineral classes present in the cometary grains
Evidence for the formation of comet 67P/Churyumov-Gerasimenko through gravitational collapse of a bound clump of pebbles
The processes that led to the formation of the planetary bodies in the Solar System are still not fully understood. Using the results obtained with the comprehensive suite of instruments on-board ESAâs Rosetta mission, we present evidence that comet 67P/Churyumov-Gerasimenko likely formed through the gentle gravitational collapse of a bound clump of mm-sized dust aggregates (âpebblesâ), intermixed with microscopic ice particles. This formation scenario leads to a cometary make-up that is simultaneously compatible with the global porosity, homogeneity, tensile strength, thermal inertia, vertical temperature profiles, sizes and porosities of emitted dust, and the steep increase in water-vapour production rate with decreasing heliocentric distance, measured by the instruments on-board the Rosetta spacecraft and the Philae lander. Our findings suggest that the pebbles observed to be abundant in protoplanetary discs around young stars provide the building material for comets and other minor bodies
Carbon-rich dust in comet 67P/Churyumov-Gerasimenko measured by COSIMA/Rosetta
Cometary ices are rich in CO2, CO and organic volatile
compounds, but the carbon content of cometary dust was only measured for
the Oort Cloud comet 1P/Halley, during its flyby in 1986. The COmetary
Secondary Ion Mass Analyzer (COSIMA)/Rosetta mass spectrometer
analysed dust particles with sizes ranging from 50 to 1000Â ÎŒm, collected
over 2 yr, from 67P/Churyumov-Gerasimenko (67P), a Jupiter family
comet. Here, we report 67P dust composition focusing on the elements C
and O. It has a high carbon content (atomic | |â )
close to the solar value and comparable to the 1P/Halley data. From
COSIMA measurements, we conclude that 67P particles are made of nearly
50 per cent organic matter in mass, mixed with mineral phases that are
mostly anhydrous. The whole composition, rich in carbon and non-hydrated
minerals, points to a primitive matter that likely preserved its
initial characteristics since the comet accretion in the outer regions
of the protoplanetary disc.</p
Nitrogen-to-carbon atomic ratio measured by COSIMA in the particles of comet 67P/ChuryumovâGerasimenko
The COmetary Secondary Ion Mass Analyzer (COSIMA) on board the Rosetta mission has analysed numerous cometary dust particles collected at very low velocities (a few m sâ1)
in the environment of comet 67P/ChuryumovâGerasimenko (hereafter 67P).
In these particles, carbon and nitrogen are expected mainly to be part
of the organic matter. We have measured the nitrogen-to-carbon (N/C)
atomic ratio of 27 cometary particles. It ranges from 0.018 to 0.06 with
an averaged value of 0.035 ± 0.011. This is compatible with the
measurements of the particles of comet 1P/Halley and is in the lower
range of the values measured in comet 81P/Wild 2 particles brought back
to Earth by the Stardust mission. Moreover, the averaged value
found in 67P particles is also similar to the one found in the insoluble
organic matter extracted from CM, CI and CR carbonaceous chondrites and
to the bulk values measured in most interplanetary dust particles and
micrometeorites. The close agreement of the N/C atomic ratio in all
these objects indicates that their organic matters share some
similarities and could have a similar chemical origin. Furthermore,
compared to the abundances of all the detected elements in the particles
of 67P and to the elemental solar abundances, the nitrogen is depleted
in the particles and the nucleus of 67P as was previously inferred also
for comet 1P/Halley. This nitrogen depletion could constrain the
formation scenarios of cometary nuclei.</p
Laboratory analyses of extraterrestrial materials and of their synthetic analogs
LâĂ©tude en laboratoire de matĂ©riaux extraterrestres provenant dâobjets ayant peu ou pas Ă©voluĂ© depuis leur formation il y a environ 4.6 milliards dâannĂ©es, peut amĂ©liorer notre connaissance sur les dĂ©buts de notre systĂšme planĂ©taire. Par ailleurs, la simulation en laboratoire de certains processus que ces matĂ©riaux sont susceptibles de subir au cours de leur histoire apporte Ă©galement de prĂ©cieuses informations pour lâinterprĂ©tation des donnĂ©es issues des observations astronomiques ainsi que pour la comprĂ©hension de lâĂ©volution des solides du Milieu Interstellaire jusquâĂ leur incorporation dans des objets planĂ©taires, objets incluant aussi toutes sortes de dĂ©bris tels que les astĂ©roĂdes, les comĂštes et toutes sortes de poussiĂšres accessibles Ă la collecte et/ou Ă lâobservation.Au cours de cette thĂšse, lâanalyse des matĂ©riaux organiques ainsi que des matĂ©riaux silicatĂ©s, jusquâalors peu Ă©tudiĂ©s conjointement, dans les poussiĂšres stratosphĂ©riques dâorigine cosmique, rĂ©vĂšle une corrĂ©lation entre la minĂ©ralogie des grains et la longueur des chaĂźnes carbonĂ©es. Ce lien ne semble pas le fruit de processus Ă la surface des corps parents des grains mais semble plutĂŽt tracer des processus prĂ©-accrĂ©tionnels. La conservation de composants peu altĂ©rĂ©s sur les corps parents dans les matĂ©riaux extraterrestres est encore une fois confirmĂ©e par la dĂ©couverte, au cours de cette thĂšse, dâinclusions dans la mĂ©tĂ©orite carbonĂ©e « Paris » dont les spectres infrarouges sont trĂšs similaires Ă ceux des composĂ©s carbonĂ©s observĂ©s dans le Milieu Interstellaire. LâĂ©tude de grains comĂ©taires issus de la mission spatiale Stardust a montrĂ©, contrairement Ă lâidĂ©e que les comĂštes soient composĂ©es uniquement de matĂ©riaux primitifs puisque conservĂ©s dans un rĂ©servoir froid, que celles-ci contiennent aussi un certain nombre de matĂ©riaux formĂ©s Ă haute tempĂ©rature, confirmant alors de prĂ©cĂ©dentes analyses dâĂ©chantillons de Stardust et impliquant des Ă©changes de matĂ©riaux Ă grande Ă©chelle radiale dans le jeune SystĂšme solaire.La deuxiĂšme partie de ce travail, consacrĂ©e Ă lâĂ©tude dâanalogues de matiĂšre extraterrestre, porte sur le rĂŽle quâont pu jouer les matĂ©riaux Ă partir desquels les planĂštes telluriques se sont formĂ©es dans lâapport de lâeau sur la Terre dans le cadre du scĂ©nario dit de « wet accretion ». Les expĂ©riences effectuĂ©es au cours de cette thĂšse visant Ă simuler les interactions entre silicates et vapeur dâeau ont montrĂ© que ces matĂ©riaux permettent de stocker dâimportantes quantitĂ©s dâeau Ă leur surface par adsorption des molĂ©cules de la phase gazeuse.Laboratory analyses performed on extraterrestrial materials originating from primitive bodies of our Solar System, that are bodies known to have suffered low alteration since their formation 4.6 billion years ago, can improve our knowledge on processes that have occurred in the early phase of our planetary system. Furthermore, laboratory simulations of some processes that these materials are likely to suffer during their life cycle also bring precious indications for interpreting observational data as well as for understanding the evolution of solids from the Interstellar Medium to their incorporation into planetary bodies, these latter including asteroids, comets and all kinds of dust that may be observed and/or collected back to Earth.During this thesis, the analysis of silicate as well as organic materials, which have not been much studied jointly so far, in stratospheric particles of cosmic origin, reveals a correlation between the mineralogy of the grains and the lengths of the chains of their carbonaceous component. This link does not seem to be due to parent body processing but rather to trace pre-accretionnal processes. The preservation of pristine components in extraterrestrial materials slightly altered on their parent bodies is again confirmed by the discovery in this work, of inclusions in the âParisâ carbonaceous chondrite whose infrared spectra are similar to the interstellar carbonaceous species. The study of cometary grains from the Stardust space mission showed, unlike the common idea that comets should be composed only of primitive materials since they reside in a cold reservoir, that comets do also contain a number of materials formed at high temperature, thus confirming results from previous studies of Stardust samples and implying large-scale radial mixing of materials in the young Solar system disk.The second part of my work, dedicated to experiments on primitive extraterrestrial amorphous silicates analogs, is aimed to study the role that materials from which Earth has accreted could have played in its water budget in the frame of the âwet accretionâ scenario. The experiments performed along this thesis simulating interactions between silicates and water vapor, showed that silicates allow the storage of large quantities of water by adsorption onto their surface of molecules directly from the gas phase
Etude en laboratoire de grains extraterrestres et de leurs analogues de synthĂšse
Laboratory analyses performed on extraterrestrial materials originating from primitive bodies of our Solar System, that are bodies known to have suffered low alteration since their formation 4.6 billion years ago, can improve our knowledge on processes that have occurred in the early phase of our planetary system. Furthermore, laboratory simulations of some processes that these materials are likely to suffer during their life cycle also bring precious indications for interpreting observational data as well as for understanding the evolution of solids from the Interstellar Medium to their incorporation into planetary bodies, these latter including asteroids, comets and all kinds of dust that may be observed and/or collected back to Earth.During this thesis, the analysis of silicate as well as organic materials, which have not been much studied jointly so far, in stratospheric particles of cosmic origin, reveals a correlation between the mineralogy of the grains and the lengths of the chains of their carbonaceous component. This link does not seem to be due to parent body processing but rather to trace pre-accretionnal processes. The preservation of pristine components in extraterrestrial materials slightly altered on their parent bodies is again confirmed by the discovery in this work, of inclusions in the âParisâ carbonaceous chondrite whose infrared spectra are similar to the interstellar carbonaceous species. The study of cometary grains from the Stardust space mission showed, unlike the common idea that comets should be composed only of primitive materials since they reside in a cold reservoir, that comets do also contain a number of materials formed at high temperature, thus confirming results from previous studies of Stardust samples and implying large-scale radial mixing of materials in the young Solar system disk.The second part of my work, dedicated to experiments on primitive extraterrestrial amorphous silicates analogs, is aimed to study the role that materials from which Earth has accreted could have played in its water budget in the frame of the âwet accretionâ scenario. The experiments performed along this thesis simulating interactions between silicates and water vapor, showed that silicates allow the storage of large quantities of water by adsorption onto their surface of molecules directly from the gas phase.LâĂ©tude en laboratoire de matĂ©riaux extraterrestres provenant dâobjets ayant peu ou pas Ă©voluĂ© depuis leur formation il y a environ 4.6 milliards dâannĂ©es, peut amĂ©liorer notre connaissance sur les dĂ©buts de notre systĂšme planĂ©taire. Par ailleurs, la simulation en laboratoire de certains processus que ces matĂ©riaux sont susceptibles de subir au cours de leur histoire apporte Ă©galement de prĂ©cieuses informations pour lâinterprĂ©tation des donnĂ©es issues des observations astronomiques ainsi que pour la comprĂ©hension de lâĂ©volution des solides du Milieu Interstellaire jusquâĂ leur incorporation dans des objets planĂ©taires, objets incluant aussi toutes sortes de dĂ©bris tels que les astĂ©roĂdes, les comĂštes et toutes sortes de poussiĂšres accessibles Ă la collecte et/ou Ă lâobservation.Au cours de cette thĂšse, lâanalyse des matĂ©riaux organiques ainsi que des matĂ©riaux silicatĂ©s, jusquâalors peu Ă©tudiĂ©s conjointement, dans les poussiĂšres stratosphĂ©riques dâorigine cosmique, rĂ©vĂšle une corrĂ©lation entre la minĂ©ralogie des grains et la longueur des chaĂźnes carbonĂ©es. Ce lien ne semble pas le fruit de processus Ă la surface des corps parents des grains mais semble plutĂŽt tracer des processus prĂ©-accrĂ©tionnels. La conservation de composants peu altĂ©rĂ©s sur les corps parents dans les matĂ©riaux extraterrestres est encore une fois confirmĂ©e par la dĂ©couverte, au cours de cette thĂšse, dâinclusions dans la mĂ©tĂ©orite carbonĂ©e « Paris » dont les spectres infrarouges sont trĂšs similaires Ă ceux des composĂ©s carbonĂ©s observĂ©s dans le Milieu Interstellaire. LâĂ©tude de grains comĂ©taires issus de la mission spatiale Stardust a montrĂ©, contrairement Ă lâidĂ©e que les comĂštes soient composĂ©es uniquement de matĂ©riaux primitifs puisque conservĂ©s dans un rĂ©servoir froid, que celles-ci contiennent aussi un certain nombre de matĂ©riaux formĂ©s Ă haute tempĂ©rature, confirmant alors de prĂ©cĂ©dentes analyses dâĂ©chantillons de Stardust et impliquant des Ă©changes de matĂ©riaux Ă grande Ă©chelle radiale dans le jeune SystĂšme solaire.La deuxiĂšme partie de ce travail, consacrĂ©e Ă lâĂ©tude dâanalogues de matiĂšre extraterrestre, porte sur le rĂŽle quâont pu jouer les matĂ©riaux Ă partir desquels les planĂštes telluriques se sont formĂ©es dans lâapport de lâeau sur la Terre dans le cadre du scĂ©nario dit de « wet accretion ». Les expĂ©riences effectuĂ©es au cours de cette thĂšse visant Ă simuler les interactions entre silicates et vapeur dâeau ont montrĂ© que ces matĂ©riaux permettent de stocker dâimportantes quantitĂ©s dâeau Ă leur surface par adsorption des molĂ©cules de la phase gazeuse