The recent passage of the Hale–Bopp (C/1995 O1) comet has provided the first opportunity to analy... more The recent passage of the Hale–Bopp (C/1995 O1) comet has provided the first opportunity to analyse the infrared spectral properties of a bright comet both from the ground and by the ISO space observatory. Previous works have already been dedicated to study the potential candidates to reproduce the cometary feature at 10 μm observed for different comets. We have applied
Ground and space born spectroscopic observations have shown that crystalline Mg-rich silicates ar... more Ground and space born spectroscopic observations have shown that crystalline Mg-rich silicates are among the main components of cometary grains. We have produced amorphous Mg-rich pyroxene particles by laser evaporation of natural mineral. Thermal annealing of the material has been performed at 800 and 1000 ° C for different time lags. Composition and morphological properties of the samples have been
... As far as space telescopes are concerned, Herschel/HIFI will allow the systematic study of D ... more ... As far as space telescopes are concerned, Herschel/HIFI will allow the systematic study of D ... are grossly depleted in comparison with solar and cosmic abundances; this observation is consistent ... augment the meager ancient rock record on Earth with rocks from Mars, which has ...
Aims:The aim of this paper is to investigate the surface composition of the two asteroids 21 Lute... more Aims:The aim of this paper is to investigate the surface composition of the two asteroids 21 Lutetia and 2867 Steins, targets of the Rosetta space mission. Methods: We observed the two asteroids through their full rotational periods with the Infrared Spectrograph of the Spitzer Space Telescope to investigate the surface properties. The analysis of their thermal emission spectra was carried
Interplanetary dust particles (IDPs) and meteorites provide an unique opportunity to study extrat... more Interplanetary dust particles (IDPs) and meteorites provide an unique opportunity to study extraterrestrial materials in laboratory. Different Raman studies have shown that most of IDPs exhibit the characteristic amorphous carbon Raman feature. Different degrees of order have been recognised in the amorphous carbon phase of IDPs testifying either to different origin or to different processing under different physical conditions (temperature,
We have measured the absorption coefficient per unit mass of cosmic dust analog grains, crystalli... more We have measured the absorption coefficient per unit mass of cosmic dust analog grains, crystalline fayalite and forsterite, amorphous fayalite, and two kinds of disordered carbon grains, between 20 km and 2 mm over the temperature range 295È24 K. The results provide evidence of a signiÐcant dependence on temperature. The opacity systematically decreases with decreasing temperature ; at 1 mm, it varies by a factor of between 1.9 and 5.8, depending on the material, from room temperature to 24 K. The variations are more marked for the amorphous grains. The wavelength dependence of the absorption coefficient is well Ðtted by a power law with exponent b that varies with temperature. For the two amorphous carbons, b(24 K) D1.2 with increases of 24% and 50% with respect to the room-temperature values. A 50% increase is found for amorphous fayalite, characterized by b(24 K) \ 2. A less pronounced change of b with temperature, 14% and 10%, is observed for crystalline forsterite, b(24 K) \ 2.2, and fayalite, b(24 K) \ 2.3, respectively. For amorphous fayalite grains, the millimeter opacity at 24 K is larger by a factor of D4 than that of the crystalline counterpart. In addition, a temperature dependence of the infrared bands present in the spectrum of the two crystalline silicates is found. The features become more intense, sharpen, and shift to slightly higher frequencies with decreasing temperature. The results are discussed in terms of intrinsic far-infraredÈmillimeter absorption mechanisms. The linear dependence of the millimeter absorption on temperature suggests that two-phonon di †erence processes play a dominant role.
Stellar nucleosynthesis of heavy elements such as carbon allowed the formation of organic molecul... more Stellar nucleosynthesis of heavy elements such as carbon allowed the formation of organic molecules in space, which appear to be widespread in our Galaxy. The physical and chemical conditions-including density, temperature, ultraviolet (UV) radiation and energetic particles-determine reaction pathways and the complexity of organic molecules in different space environments. Dense interstellar clouds are the birth sites of stars of all masses and their planetary systems. During the protostellar collapse, interstellar organic molecules in gaseous and solid phases are integrated into protostellar disks from which planets and smaller solar 0034-4885/02/101427+61$90.00
Since their formation in the outflows of evolved stars, materials suffer in space deep chemical a... more Since their formation in the outflows of evolved stars, materials suffer in space deep chemical and physical modifications. Most abundant elements (C, N, O, Mg, Si, S and Fe) are present in dust as refractory chemical species. Among them silicates are one of the main constituents. Spectroscopic observations in various astronomical environments have shown that magnesium rich silicates are present both in amorphous and in crystalline form. An accurate interpretation of these observations requires studies on the formation of silicate dust in the atmospheres of giant stars and their evolution in the interstellar medium until their inclusion in protoplanetary disks.Many theoretical works have described the chemical and physical evolution of solids in space and their link to observable optical properties. Laboratory studies of cosmic dust analogues are needed to investigate these processes experimentally.In this work, experiments aimed at simulating the formation of silicates in space are presented. In particular, the laser ablation technique is used to produce amorphous silicates with various Si–Mg–Fe content. The analysis of their thermal evolution is presented.
The Life Marker Chip (LMC) is one of the instruments being developed for possible flight on the 2... more The Life Marker Chip (LMC) is one of the instruments being developed for possible flight on the 2018 ExoMars mission. The instrument uses solvents to extract organic compounds from samples of martian regolith and to transfer the extracts to dedicated detectors based around the use of antibodies. The scientific aims of the instrument are to detect organics in the form of biomarkers that might be associated with extinct life, extant life or abiotic sources of organics. The instrument relies on a novel surfactantbased solvent system and bespoke, commercial and research-developed antibodies against a number of distinct biomarkers or molecular types. The LMC comprises of a number of subsystems designed to accept up to four discrete samples of martian regolith or crushed rock, implement the solvent extraction, perform microfluidic-based multiplexed antibody-assays for biomarkers and other targets, optically detect the fluorescent output of the assays, control the internal instrument pressure and temperature, in addition to the associated instrument control electronics and software. The principle of operation, the design and the instrument development status as of December 2011 are reported here. The instrument principle can be extended to other configurations and missions as needed.
available online at Abstract-We report combined micro-infrared, micro-Raman, and field emission s... more available online at Abstract-We report combined micro-infrared, micro-Raman, and field emission scanning electron microscope (FESEM) analyses of particles collected by the Stardust spacecraft during its flyby of comet 81P/Wild 2 on 2 January 2004 and successfully returned back to Earth on 15 January 2006. We present mid-infrared (IR) spectra of six of these particles. The CH 2 /CH 3 ratios inferred from the infrared data are greater than those seen in organics in the diffuse interstellar medium, possibly indicating the presence of longer or less branched aliphatic chains. The micro-Raman data offer insights into the state of the order of the carbonaceous component present in the particles. Raman parameters for most of the particles span a similar range to that observed in interplanetary dust particles (IDPs) and the most primitive meteorites. Both the IR and Raman data imply the presence of a very labile carbonaceous component. Hydrated silicates may be present in two particles of Track 35, one of which may also contain carbonates, but further investigations with other techniques need to be performed to confirm these findings. In some cases, the analyses are difficult to interpret because of the presence of compressed aerogel mixed with the grains.
The laboratory analyses of cosmic dust analogues-that in the context ofthis paper include interst... more The laboratory analyses of cosmic dust analogues-that in the context ofthis paper include interstellar, circumstellar as well as cometary dust-have a critical role in the study of circumstellar and cometary dust. The morphological, structural and chemical characterization of these analogues are critical for comparisons oftheir infrared and ultraviolet spectra with those obtained by astronomical observations, as well as for modeling purposes. Besides, the results from these laboratory studies are important to the success of space missions to comets when testing and calibrating the payload instruments. The interpretations of returned scientific data would benefit from the comparison with data recorded by the instruments in a laboratory setting for different classes ofpreviously characterized analogues. We produced various types ofcondensed samples: (1) Mg,Fe-silicates, (olivine, pyroxene), (2) carbon-rich dust, and (3) mixed carbon-silicate dust. The samples were prepared using different techniques, viz. (1) laser bombardment of solid targets in an Ar and 02 atmosphere, (2) arc discharge in an Ar and H2 atmosphere, and (3) grinding powders of natural minerals. We simulated various post-condensation processes, such as thermal annealing, ultraviolet irradiation, ion bombardment and exposure to atomic hydrogen. These processes produced compound samples of a wide range of physico-chemical properties. To identify their textures, morphologies, grain compositions and crystallographic properties we used electron microscopy and far-ultraviolet to far-infrared (millimeter range) spectroscopy.
In the interstellar medium (ISM), an important channel of water formation is the reaction of atom... more In the interstellar medium (ISM), an important channel of water formation is the reaction of atoms on the surface of dust grains. Here, we report on a laboratory study of the formation of water via the O+D reaction network. While prior studies were done on ices, as appropriate to the formation of water in dense clouds, we explored how water formation occurs on bare surfaces, i.e., in conditions mimicking the transition from diffuse to dense clouds (Av ∼ 1-5). Reaction products were detected during deposition and afterward when the sample is brought to a high temperature. We quantified the formation of water and intermediary products, such as D 2 O 2 , over a range of surface temperatures (15-25 K). The detection of OD on the surface signals the importance of this reactant in the overall scheme of water formation in the ISM.
We present the results of ISOCAM observations performed on Comets 2P/Encke and 103P/Hartley 2, on... more We present the results of ISOCAM observations performed on Comets 2P/Encke and 103P/Hartley 2, on 31 October 1997 and 1 January 1998, respectively. Images were obtained in the broadband filters LW3 (centered at 15.00 µm) and LW10 (centered at 11.50 µm). Tail models have been applied to the images to analyze the evolution of the dust coma environment and to derive infor-1 Based on observation with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, the Netherland, and the United Kingdom) with the participation of ISAS and NASA. mation about the velocity of the grains. The image of 2P/Encke presents a sunward spike interpreted as a Neck-Line. Thanks to the model, the time evolution of the comet dust environment during 3 months preceding the observation has been reconstructed. 2P/Encke presents a strong maximum in the dust velocity, a broad maximum of the dust mass loss rate, and a dip of the size distribution power index around perihelion. Model results indicate that the largest grains in the tail can reach sizes from centimeters to decimeters. This has important implications for the source of the Taurid meteoroids. For Comet 103P/Hartley 2 the numerical model suggests an anisotropic dust ejection with a tail composed of grains smaller than those in 2P/Encke. Both dust ejection velocity and dust mass loss rate reach a maximum about 2 weeks before perihelion. The power law best fitting the time-averaged size distribution of both comets has an index of about −3.2, indicating that the released dust is strongly dominated in mass by the largest ejected grains.
Observations of emissivity features of 10 Hygiea have been made for the first time in the relativ... more Observations of emissivity features of 10 Hygiea have been made for the first time in the relatively unexplored thermal-infrared wave-1 Based on observations with ISO, an ESA (European Space Agency) project with instruments founded by ESA Member States (especially the PI countries: France, Germany, the Netherlands, and the United Kingdom) with the participation of ISAS and NASA. length region with the ISO (Infrared Space Observatory) satellite. Spectrophotomer (PHT-S) and short wavelength spectrometer (SWS) spectra of 10 Hygiea, obtained at 5.8-11.6 and 7-45 µm, respectively, are presented. In order to remove the thermal emission continuum, an advanced thermo-physical model has been applied to the observational data. To better interpret the spectral features above the thermal emission continuum, we compared the ISO observations with laboratory spectra available in the literature.
How to cite: Barucci, M. A.; Yoshikawa, M.; Michel, P.; Kawaguchi, J.; Yano, H.; Brucato, J. R.; ... more How to cite: Barucci, M. A.; Yoshikawa, M.; Michel, P.; Kawaguchi, J.; Yano, H.; Brucato, J. R.; Franchi, I. A.; Dotto, E.; Fulchignoni, M.; Ulamec, S.; Boehnhardt, H.; Coradini, M.; Green, S. F.; Josset, J.-L.; Koschny, D.; Muinonen, K.; Oberst, J. and Marco Polo, Science Team (2008). Marco Polo: A near Earth object sample return mission.
Silicates are one of the principal components present in Solar System objects. Silicates evolve i... more Silicates are one of the principal components present in Solar System objects. Silicates evolve in space modifying their physical properties according to the astronomical environments they go through. To characterise the nature of TNOs in the framework of the formation and evolution of the Solar System, experiments on structural transitions of silicates have been performed in laboratory with the aim to simulate some of the processing suffered by the dust. The infrared spectral properties of possible silicates candidate thought to be present in TNOs have been studied. The results of thermal annealing of amorphous silicates and amorphisation of crystalline forsterite (pure-Mg olivine) by ion irradiation are presented. The observable properties of TNOs surfaces are inferred.
The recent passage of the Hale–Bopp (C/1995 O1) comet has provided the first opportunity to analy... more The recent passage of the Hale–Bopp (C/1995 O1) comet has provided the first opportunity to analyse the infrared spectral properties of a bright comet both from the ground and by the ISO space observatory. Previous works have already been dedicated to study the potential candidates to reproduce the cometary feature at 10 μm observed for different comets. We have applied
Ground and space born spectroscopic observations have shown that crystalline Mg-rich silicates ar... more Ground and space born spectroscopic observations have shown that crystalline Mg-rich silicates are among the main components of cometary grains. We have produced amorphous Mg-rich pyroxene particles by laser evaporation of natural mineral. Thermal annealing of the material has been performed at 800 and 1000 ° C for different time lags. Composition and morphological properties of the samples have been
... As far as space telescopes are concerned, Herschel/HIFI will allow the systematic study of D ... more ... As far as space telescopes are concerned, Herschel/HIFI will allow the systematic study of D ... are grossly depleted in comparison with solar and cosmic abundances; this observation is consistent ... augment the meager ancient rock record on Earth with rocks from Mars, which has ...
Aims:The aim of this paper is to investigate the surface composition of the two asteroids 21 Lute... more Aims:The aim of this paper is to investigate the surface composition of the two asteroids 21 Lutetia and 2867 Steins, targets of the Rosetta space mission. Methods: We observed the two asteroids through their full rotational periods with the Infrared Spectrograph of the Spitzer Space Telescope to investigate the surface properties. The analysis of their thermal emission spectra was carried
Interplanetary dust particles (IDPs) and meteorites provide an unique opportunity to study extrat... more Interplanetary dust particles (IDPs) and meteorites provide an unique opportunity to study extraterrestrial materials in laboratory. Different Raman studies have shown that most of IDPs exhibit the characteristic amorphous carbon Raman feature. Different degrees of order have been recognised in the amorphous carbon phase of IDPs testifying either to different origin or to different processing under different physical conditions (temperature,
We have measured the absorption coefficient per unit mass of cosmic dust analog grains, crystalli... more We have measured the absorption coefficient per unit mass of cosmic dust analog grains, crystalline fayalite and forsterite, amorphous fayalite, and two kinds of disordered carbon grains, between 20 km and 2 mm over the temperature range 295È24 K. The results provide evidence of a signiÐcant dependence on temperature. The opacity systematically decreases with decreasing temperature ; at 1 mm, it varies by a factor of between 1.9 and 5.8, depending on the material, from room temperature to 24 K. The variations are more marked for the amorphous grains. The wavelength dependence of the absorption coefficient is well Ðtted by a power law with exponent b that varies with temperature. For the two amorphous carbons, b(24 K) D1.2 with increases of 24% and 50% with respect to the room-temperature values. A 50% increase is found for amorphous fayalite, characterized by b(24 K) \ 2. A less pronounced change of b with temperature, 14% and 10%, is observed for crystalline forsterite, b(24 K) \ 2.2, and fayalite, b(24 K) \ 2.3, respectively. For amorphous fayalite grains, the millimeter opacity at 24 K is larger by a factor of D4 than that of the crystalline counterpart. In addition, a temperature dependence of the infrared bands present in the spectrum of the two crystalline silicates is found. The features become more intense, sharpen, and shift to slightly higher frequencies with decreasing temperature. The results are discussed in terms of intrinsic far-infraredÈmillimeter absorption mechanisms. The linear dependence of the millimeter absorption on temperature suggests that two-phonon di †erence processes play a dominant role.
Stellar nucleosynthesis of heavy elements such as carbon allowed the formation of organic molecul... more Stellar nucleosynthesis of heavy elements such as carbon allowed the formation of organic molecules in space, which appear to be widespread in our Galaxy. The physical and chemical conditions-including density, temperature, ultraviolet (UV) radiation and energetic particles-determine reaction pathways and the complexity of organic molecules in different space environments. Dense interstellar clouds are the birth sites of stars of all masses and their planetary systems. During the protostellar collapse, interstellar organic molecules in gaseous and solid phases are integrated into protostellar disks from which planets and smaller solar 0034-4885/02/101427+61$90.00
Since their formation in the outflows of evolved stars, materials suffer in space deep chemical a... more Since their formation in the outflows of evolved stars, materials suffer in space deep chemical and physical modifications. Most abundant elements (C, N, O, Mg, Si, S and Fe) are present in dust as refractory chemical species. Among them silicates are one of the main constituents. Spectroscopic observations in various astronomical environments have shown that magnesium rich silicates are present both in amorphous and in crystalline form. An accurate interpretation of these observations requires studies on the formation of silicate dust in the atmospheres of giant stars and their evolution in the interstellar medium until their inclusion in protoplanetary disks.Many theoretical works have described the chemical and physical evolution of solids in space and their link to observable optical properties. Laboratory studies of cosmic dust analogues are needed to investigate these processes experimentally.In this work, experiments aimed at simulating the formation of silicates in space are presented. In particular, the laser ablation technique is used to produce amorphous silicates with various Si–Mg–Fe content. The analysis of their thermal evolution is presented.
The Life Marker Chip (LMC) is one of the instruments being developed for possible flight on the 2... more The Life Marker Chip (LMC) is one of the instruments being developed for possible flight on the 2018 ExoMars mission. The instrument uses solvents to extract organic compounds from samples of martian regolith and to transfer the extracts to dedicated detectors based around the use of antibodies. The scientific aims of the instrument are to detect organics in the form of biomarkers that might be associated with extinct life, extant life or abiotic sources of organics. The instrument relies on a novel surfactantbased solvent system and bespoke, commercial and research-developed antibodies against a number of distinct biomarkers or molecular types. The LMC comprises of a number of subsystems designed to accept up to four discrete samples of martian regolith or crushed rock, implement the solvent extraction, perform microfluidic-based multiplexed antibody-assays for biomarkers and other targets, optically detect the fluorescent output of the assays, control the internal instrument pressure and temperature, in addition to the associated instrument control electronics and software. The principle of operation, the design and the instrument development status as of December 2011 are reported here. The instrument principle can be extended to other configurations and missions as needed.
available online at Abstract-We report combined micro-infrared, micro-Raman, and field emission s... more available online at Abstract-We report combined micro-infrared, micro-Raman, and field emission scanning electron microscope (FESEM) analyses of particles collected by the Stardust spacecraft during its flyby of comet 81P/Wild 2 on 2 January 2004 and successfully returned back to Earth on 15 January 2006. We present mid-infrared (IR) spectra of six of these particles. The CH 2 /CH 3 ratios inferred from the infrared data are greater than those seen in organics in the diffuse interstellar medium, possibly indicating the presence of longer or less branched aliphatic chains. The micro-Raman data offer insights into the state of the order of the carbonaceous component present in the particles. Raman parameters for most of the particles span a similar range to that observed in interplanetary dust particles (IDPs) and the most primitive meteorites. Both the IR and Raman data imply the presence of a very labile carbonaceous component. Hydrated silicates may be present in two particles of Track 35, one of which may also contain carbonates, but further investigations with other techniques need to be performed to confirm these findings. In some cases, the analyses are difficult to interpret because of the presence of compressed aerogel mixed with the grains.
The laboratory analyses of cosmic dust analogues-that in the context ofthis paper include interst... more The laboratory analyses of cosmic dust analogues-that in the context ofthis paper include interstellar, circumstellar as well as cometary dust-have a critical role in the study of circumstellar and cometary dust. The morphological, structural and chemical characterization of these analogues are critical for comparisons oftheir infrared and ultraviolet spectra with those obtained by astronomical observations, as well as for modeling purposes. Besides, the results from these laboratory studies are important to the success of space missions to comets when testing and calibrating the payload instruments. The interpretations of returned scientific data would benefit from the comparison with data recorded by the instruments in a laboratory setting for different classes ofpreviously characterized analogues. We produced various types ofcondensed samples: (1) Mg,Fe-silicates, (olivine, pyroxene), (2) carbon-rich dust, and (3) mixed carbon-silicate dust. The samples were prepared using different techniques, viz. (1) laser bombardment of solid targets in an Ar and 02 atmosphere, (2) arc discharge in an Ar and H2 atmosphere, and (3) grinding powders of natural minerals. We simulated various post-condensation processes, such as thermal annealing, ultraviolet irradiation, ion bombardment and exposure to atomic hydrogen. These processes produced compound samples of a wide range of physico-chemical properties. To identify their textures, morphologies, grain compositions and crystallographic properties we used electron microscopy and far-ultraviolet to far-infrared (millimeter range) spectroscopy.
In the interstellar medium (ISM), an important channel of water formation is the reaction of atom... more In the interstellar medium (ISM), an important channel of water formation is the reaction of atoms on the surface of dust grains. Here, we report on a laboratory study of the formation of water via the O+D reaction network. While prior studies were done on ices, as appropriate to the formation of water in dense clouds, we explored how water formation occurs on bare surfaces, i.e., in conditions mimicking the transition from diffuse to dense clouds (Av ∼ 1-5). Reaction products were detected during deposition and afterward when the sample is brought to a high temperature. We quantified the formation of water and intermediary products, such as D 2 O 2 , over a range of surface temperatures (15-25 K). The detection of OD on the surface signals the importance of this reactant in the overall scheme of water formation in the ISM.
We present the results of ISOCAM observations performed on Comets 2P/Encke and 103P/Hartley 2, on... more We present the results of ISOCAM observations performed on Comets 2P/Encke and 103P/Hartley 2, on 31 October 1997 and 1 January 1998, respectively. Images were obtained in the broadband filters LW3 (centered at 15.00 µm) and LW10 (centered at 11.50 µm). Tail models have been applied to the images to analyze the evolution of the dust coma environment and to derive infor-1 Based on observation with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, the Netherland, and the United Kingdom) with the participation of ISAS and NASA. mation about the velocity of the grains. The image of 2P/Encke presents a sunward spike interpreted as a Neck-Line. Thanks to the model, the time evolution of the comet dust environment during 3 months preceding the observation has been reconstructed. 2P/Encke presents a strong maximum in the dust velocity, a broad maximum of the dust mass loss rate, and a dip of the size distribution power index around perihelion. Model results indicate that the largest grains in the tail can reach sizes from centimeters to decimeters. This has important implications for the source of the Taurid meteoroids. For Comet 103P/Hartley 2 the numerical model suggests an anisotropic dust ejection with a tail composed of grains smaller than those in 2P/Encke. Both dust ejection velocity and dust mass loss rate reach a maximum about 2 weeks before perihelion. The power law best fitting the time-averaged size distribution of both comets has an index of about −3.2, indicating that the released dust is strongly dominated in mass by the largest ejected grains.
Observations of emissivity features of 10 Hygiea have been made for the first time in the relativ... more Observations of emissivity features of 10 Hygiea have been made for the first time in the relatively unexplored thermal-infrared wave-1 Based on observations with ISO, an ESA (European Space Agency) project with instruments founded by ESA Member States (especially the PI countries: France, Germany, the Netherlands, and the United Kingdom) with the participation of ISAS and NASA. length region with the ISO (Infrared Space Observatory) satellite. Spectrophotomer (PHT-S) and short wavelength spectrometer (SWS) spectra of 10 Hygiea, obtained at 5.8-11.6 and 7-45 µm, respectively, are presented. In order to remove the thermal emission continuum, an advanced thermo-physical model has been applied to the observational data. To better interpret the spectral features above the thermal emission continuum, we compared the ISO observations with laboratory spectra available in the literature.
How to cite: Barucci, M. A.; Yoshikawa, M.; Michel, P.; Kawaguchi, J.; Yano, H.; Brucato, J. R.; ... more How to cite: Barucci, M. A.; Yoshikawa, M.; Michel, P.; Kawaguchi, J.; Yano, H.; Brucato, J. R.; Franchi, I. A.; Dotto, E.; Fulchignoni, M.; Ulamec, S.; Boehnhardt, H.; Coradini, M.; Green, S. F.; Josset, J.-L.; Koschny, D.; Muinonen, K.; Oberst, J. and Marco Polo, Science Team (2008). Marco Polo: A near Earth object sample return mission.
Silicates are one of the principal components present in Solar System objects. Silicates evolve i... more Silicates are one of the principal components present in Solar System objects. Silicates evolve in space modifying their physical properties according to the astronomical environments they go through. To characterise the nature of TNOs in the framework of the formation and evolution of the Solar System, experiments on structural transitions of silicates have been performed in laboratory with the aim to simulate some of the processing suffered by the dust. The infrared spectral properties of possible silicates candidate thought to be present in TNOs have been studied. The results of thermal annealing of amorphous silicates and amorphisation of crystalline forsterite (pure-Mg olivine) by ion irradiation are presented. The observable properties of TNOs surfaces are inferred.
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Papers by John Brucato