From protoplanetary dust to asteroidal heating: a mineralogical study of the CO3 chondrites

Carbonaceous chondrites are among the most primitive extra-terrestrial materials available for study. These meteorites provide a detailed record of the geological processes and events that have shaped our solar system over the last 4.5 billion years. "Ornans-like" carbonaceous chondrite meteorites, also referred to as CO3 chondrites, comprise pristine, primitive mineralogy that has undergone no or minimal aqueous alteration. CO3 chondrites are also known to contain up to 3.5% carbon in the form of insoluble and soluble organic matter, graphite and carbonates. The CO3 chondrites form a suite of samples that have experienced increasing degrees of thermal metamorphism, from weakly heated CO3.0s such as Colony and DOM 08006, to strongly meta-morphosed CO3.8s such as Isna. Detailed studies of this suite of CO3 chondrites enables firstly a determination of the most primitive and earliest formed aggregates of crystalline, amorphous and organic solids, and their textural relationships from which inferences can be made regarding the nature and composition of the protoplanetary disk; and secondly quantification of the effects of parent body metamorphism on these early solar system solids. In this thesis I have studied 12 CO3 chondrites that cover the whole metamorphic sequence, namely Colony and DOM 08006 (CO3.0), NWA 7892 (CO3.05), MIL 090010 (CO3.1), Kainsaz (CO3.2), Felix (CO3.3), Ornans (CO3.4), Lancé (CO3.5), Moss and ALHA77003 (CO3.6), War-renton (CO3.7) and Isna (CO3.8). Bulk mineralogy and chemical compositions were quantified using X-ray powder diffraction (XRD) and electron probe microanalysis, and were contextualised with in-situ, spatially resolved scanning and transmission electron microscopy (TEM), and synchrotron-based scanning transmission X-ray microscopy (STXM) combined with X-ray ab-sorption near edge structure (XANES) spectroscopy. XRD was used to quantify the bulk modal mineralogy of the CO3 chondrites. I found that the most primitive samples mostly comprise Mg-rich olivine and pyroxene, and Fe-bearing amor-phous silicates. Samples between CO3.0 and CO3.1 contained ~35% forsterite, ~13% Fo60 olivine, ~26% pyroxene, ~2.5 % sulphide, ~0.7 % metal, ~5 % magnetite and ~14 % amorphous material. On heating, forsterite within the primitive samples was systematically replaced by Fe-rich olivine such that all the olivine in the CO3.8 was Fo60. This transformation was linear and could be used for rapidly and accurately defining the petrologic grade of a CO chondrite. The amorphous Febearing silicates were fully crystallised by CO3.2, magnetite had disappeared by CO3.3 and nepheline appeared at CO3.3 and gradually increases in abundance up to CO3.8. Changes in the modal mineralogy are reflected in the bulk chemistry with the matrix becoming depleted in Fe and enriched in Mg, due to equilibration with chondrules, and there is a small linear increase in Cr with increasing metamorphism. Bright-field TEM images show the fine grain size and heterogeneous texture of the matrix in the most primitive CO3 chondrites, which consists of an amorphous groundmass within which is embedded ~ 0.1 μm silicate, sulphide, metal and phyllosilicate grains. TEM imaging also revealed a systematic change in the porosity of the matrix as a function of metamorphic grade. Recrystallization and equilibration of the low porosity, low permeability matrix in the CO3.0-3.1 chondrites caused by metamorphic heating, progressively increased the porosity and average grainsize of the minerals up to CO3.8. Fe L-edge XANES analysis of the STXM data revealed that the amorphous Fe-bearing silicates and the matrix of the most primitive CO3.0 chondrites are almost fully oxidized with the Fe3+/ΣFe ratio close to 1.0. On heating the Fe becomes rapidly reduced with Kainsaz containing only about 10 % Fe3+ and Moss being dominated by Fe2+. Limited spatial variation in the Fe L-edge X-ray absorption spectra was observed in DOM 08006, most likely related to the proximity of metal and sulphides to the amorphous silicates. No significant variation in the Fe L-edge X-ray absorption spectra was observed in the silicate fraction of Moss even down to the 40 nm scale. STXM and XANES at the C, N, and O K-edges reveal spatial variations in the functional chemistry of the organic matter in the most primitive CO3 chondrites. This variation was most evident in the intensity of the aromatic, ketone and carboxyl spectral features. The presence of carbonate was also occasionally observed most particularly in and close to a ~1.3 μm wide carbonate vein in a sample of NWA 7892. As a function of increased metamorphic heating I found that the aromatic group persists while the ketone and carboxyl groups disappear such that in Moss CO3.6 only aromatic carbon was observed (with a potential trace of carbonate). Graphite was not definitively identified in any of the samples. Spectral features on the O K-edge show the progressive crystallisation of the amorphous silicate into olivine with metamorphic heating. The effects of metamorphic heating on the primitive CO3 chondrites is to crystallise the amorphous Fe-bearing silicates, systematically modify the modal mineralogy, increase the porosity of the matrix and homogenise the molecular speciation in the organic matter. Furthermore, the hydrated amorphous silicates dehydrate within a narrow temperature interval of about 100°C and there is a concomitant reduction of the Fe3+ to Fe2+ as the amorphous Fe-silicates transform into crystalline minerals. This reduction of the Fe is facilitated by the changing redox conditions likely due to the removal of oxidizing H2O and the initial presence of reducing agents such as H and C. I conclude that CO meteorites formed from anhydrous parent bodies in which minimal aqueous alteration took place and the main source of water was hydrated amorphous silicates. I propose that these amorphous silicates were hydrated in the nebula prior to accretion onto the CO parent bodies. Water within the amorphous silicates contributed to the oxidation of the Fe to Fe3+. Low porosity and limited permeability in the primitive materials restricted any fluids from circulating within the parent body. Changes from metamorphic heating released water and increased permeability such that organic matter became homogenized and subsequently partially dissociated generating a reducing environment. It is possible that the CO parent bodies had an onion shell like structure with high petrologic type COs concentrated in the inner part of the asteroid and low petrologic types closer to the surface

Pesi da telaio romani dalla Venetia fra archeologia, epigrafia e archeometria

As a part of a project conducted by the University of Padua on the wool production in the Roman Venetia, the paper focuses on a group of loom weights found in the late nineteenth century near Castagnaro (Verona). The integrated analysis (archeology, epigraphy and archaeometry) conducted on the loom weights allow to reflect on the marking of the loom weights and on the organization of the production in a Roman figlina.Nel quadro di un Progetto sulla lavorazione della lana nella Venetia romanacondotto dall’Università di Padova, il contributo presenta i risultati di un’analisi integrata fra archeologia, epigrafia e archeometria relativamente a una serie di pesi da telaio rinvenuti a fine Ottocento presso Castagnaro (Verona). I manufatti, con buona probabilità prodotti in una stessa fornace, offrono l’occasione per una riflessione sulla bollatura di tale categoria di oggetti e sull’organizzazione del lavoro nelle figlinae romane

A New Facility for the Planetary Science Community at DLR: the Planetary Sample Analysis Laboratory (SAL).

Introduction: Laboratory measurements of extra-terrestrial materials like meteorites and ultimately materials from sample return missions can significantly enhance the scientific return of the global remote sensing data. This motivated the addition of a dedicated Sample Analysis Laboratory (SAL) to complement the work of well established facilities like the Planetary Spectroscopy Laboratory (PSL) and the Astrobiology Laboratories within the Department of Planetary Laboratories at DLR, Berlin. SAL is being developed in preparation to receive samples from sample return missions such as JAXA Hayabusa 2 and MMX missions, the Chinese Chang-E 5 and 6 missions as well as the NASA Osiris-REX mission. SAL will be focusing on spectroscopic, geochemical, mineralogical analyses at microscopic level with the ultimate aim to derive information on the formation and evolution of planetary bodies and surfaces, search for traces of organic materials or even traces of extinct or extant life and presence of water. Sample Analysis Laboratory: The near-term goalis to set up the facilities on time to receive samples from the Hayabusa 2 mission. The operations have already started in 2018 with the acquisition of a vis-IR-microscope and it will continue with the acquisition of: Field Emission Gun - scanning electron microscope (FEG-SEM), Field Emission Gun – electron microprobe analyser (FEG-EMPA), X-ray diffraction (XRD) system with interchangeable optics for μXRD analysis anda polarised light microscope for high resolution imaging and mapping The facilities will be hosted in a clean room (ISO 5) equipped with glove boxes and micromanipulators to handle and prepare samples. All samples will be stored under dry nitrogen and can be transported between the instruments with dedicated shuttles in order to avoid them to enter in contact with the external environment. Based on current planning the first parts of SAL will be operational and ready for certification by end of 2022. Current facilities: To characterize and analyse the returned samples, SAL facilities will work jointly with the existing spectroscopic capabilities of PLL. PLL has the only spectroscopic infrastructure in the world with the capability to measure emissivity of powder materials, in air or in vacuum, from low to very high temperatures [1-3], over an extended spectral range from 0.2 to 200 µm. Emissivity measurements are complemented by reflectance and transmittance measurements produced simultaneously with the same set-up. Recently a vis-IR-microscope was added to extend spectral analysis to the sub-micron scale. In addition, the department is operating a Raman micro-spectrometer with a spot size on the sample in focus of <1.5 μm. The spectrometer is equipped with a cryostat serving as a planetary simulation chamber which permits simulation of environmental conditions on icy moons and planetary surfaces. PLL leads MERTIS on BepiColombo as well as the BioSign exposure experiment on the ISS. The labs have performed laboratory measurements for nearly every planetary remote sensing mission. PLL has team members on instruments on the MarsExpress, VenusExpress, MESSENGER and JAXA Hayabusa 2 and MMX missions. Most recently we joined the Hayabusa 2 Initial Sample Analysis Team.The samples analyzed at PLL range from rocks, minerals, meteorites and Apollo and Luna lunar soil samples to biological samples (e.g. pigments, cell wall molecules, lichens, bacteria, archaea and other) and samples returned from the ISS (BIOMEX) [4, 5, 6] and the asteroid Itokawa (Hayabusa sample). PLL is part of the “Distribute Planetary Simulation Facility” in European Union funded EuroPlanet Research Infrastructure (http://www.europlanet-2020-ri.eu/). Through this program (and its predecessor) over the last 9 years more than 80 external scientists have obtained time to use the PLL facilities. PLL has setup all necessary protocols to support visiting scientist, help with sample preparation, and archive the obtained data. Outlook: DLR has started establishing a Sample Analysis Laboratory. Following the approach of a distributed European sample analysis and curation facility as discussed in the preliminary recommendations of EuroCares (http://www.euro-cares.eu/) the facility at DLR could be expanded to a curation facility. The timeline for this extension will be based on the planning of sample return missions. The details will depend on the nature of the returned samples. Moreover, SAL will be running in close cooperation with the Museum für Naturkunde in Berlin and it will be operated as a community facility (e.g. Europlanet), supporting the larger German and European sample analysis community

A new laboratory facility in the era if sample return: the Sample Analysis Laboratory (SAL) at DLR Berlin

Introduction: Laboratory measurements of extra-terrestrial materials like meteorites and ultimately mate-rials from sample return missions can significantly enhance the scientific return of the global remote sensing data. This motivates the ongoing addition of a dedicated Sample Analysis Laboratory (SAL) to complement the work of well-established facilities like the Planetary Spectroscopy Laboratory (PSL) and the Astrobiology Laboratories within the Department of Planetary Laboratories at DLR, Berlin. SAL is being developed in prep-aration to receive samples from sample return missions such as JAXA Hayabusa 2 and MMX missions, the Chinese Chang-E 5 and 6 missions as well as the NASA Osiris-REX mission. SAL will be focusing on spectro-scopic, geochemical, mineralogical analyses at microscopic level with the ultimate aim to derive information on the formation and evolution of planetary bodies and surfaces, search for traces of organic materials or even traces of extinct or extant life and presence of water. Sample Analysis Laboratory: The near-term goal is to set up the facilities on time to receive samples from the Hayabusa 2 mission. The operations have already started in 2018 with the acquisition of a vis-IR-microscope, capable of collecting data in transmission and reflection modes between 0.4 and 20 µm and with a spot size of 50 µm. The microscope is equipped with a X,Y,Z motorized stage which allows the collection of large area maps and different magnifications. In the past months, a Field Emission Gun – electron microprobe analyzer (FEG-EMPA) an X-ray diffraction (XRD) system has been purchased. The system has a Bragg-Brentano geometry which can be switched to parallel beam geometry, equipped with a Cu Kα source, 1Der detector and automated incident beam optics. The system also allows to collect microdiffraction (μXRD) maps using a selection of different monocapillaries down to 140 µm in spot size. Currently ongoing are the acquisi-tions of a Field Emission Gun - scanning electron microscope (FEG-SEM) and a polarised light petrographic microscope. The facilities will be hosted in a clean room (ISO 5) equipped with glove boxes, stereo microscopes and mi-cromanipulator to handle and prepare samples. All samples will be stored under nitrogen gas (N2) and can be transported between the instruments with dedicated shuttles in order to avoid them to enter in contact with the external environment. Based on current planning the first parts of SAL will be operational and ready for certi-fication by early 2023. Outlook: In collaboration with the Natural History Museum in Berlin SAL will also have the expertise and facilities for carrying out curation of sample return material which will be made available for the whole Euro-pean scientific community. DLR is already curating a 0.45 mg of Lunar regolith collected from the Luna 24 Soviet mission and the first analyses of the material are being planned. SAL follows the approach of a distrib-uted European sample analysis and curation facility as discussed in the preliminary recommendation of Eu-roCares. Like other laboratory facilities at the DLR Institute of Planetary Research (such PSL and RMBL) which are part of the Europlanet RI, the new SAL will be from the start open to the scientific community. Our goal is to establish an excellence centre for sample analysis in Berlin within the next 5-10 years building on our collaborations with the Natural History Museum in Berlin and the Helmholtz Center Berlin as well as the universities in Berlin

Linking remote sensing, in situ and laboratory spectroscopy for a Ryugu analog meteorite sample

In 2022 JAXA issued an Announcement of Opportunity (AO) for receiving Hayabusa2 samples returned to Earth. We responded to the AO submitting a proposal based on using a multi-prong approach to achieve two main goals. The first goal is to address the subdued contrast of remote-sensing observations compared to measurements performed under laboratory conditions on analog materials. For this we will link the hyperspectral and imaging data collected from the spacecraft and the in-situ observations from the MASCOT lander instruments (MARA and MASCam) with laboratory-based measurements of Hayabusa2 samples using bi-directional reflectance spectroscopy under simulated asteroid surface conditions from UV to MIR/FIR achieved using three Bruker Vertex 80 V spectrometers in the Planetary Spectroscopy Laboratory. The second goal is the investigation of the mineralogy and organic matter of the samples collected by Hayabusa2, to better understanding the evolution of materials characterizing Ryugu and in general of protoplanetary disk and organic matter, investigating the aqueous alteration that took place in the parent body, and comparing the results with data collected from pristine carbonaceous chondrite analog meteorites. Spectral data will be complemented by Raman spectroscopy under simulated asteroid surface conditions, X-ray diffraction, would also allow us to define the bulk mineralogy of the samples as well as investigate the presence and nature of organic matter within the samples. In situ mineralogical and geochemical characterization will involve a pre-characterization of the sample fragments through scanning electron microscopy low voltage electron dispersive X-ray (EDX) maps, and micro IR analyses of the fragments. If allowed, a thin section of one grain will be used for electron microprobe analyses to geochemically characterize its mineralogical composition. To train our data collection and analysis methods on a realistic sample, we selected a piece of the Mukundpura meteorite, as one of the closer analogs to Ryugu’s surface (Ray et al., Planetary and Space Science, 2018, 151, 149–154). The Mukundpura chunk we selected for this study measures 3 mm in its maximum dimension, and we chose it so to have a test sample of the same size as the Hayabusa2 grain we requested in our proposal to JAXA’s AO. The test gave us confidence that we can measure with good SNR measurements in bi-directional reflectance for samples around 3 mm in size (see Figures 3, 4 below). To address our second goal the spectral data was complemented by Raman spectroscopy measured again under simulated asteroid surface conditions in our Raman Mineralogy and Biodetection Laboratory at DLR

MMX samples curation in Europe

In 2024 the Martian Moons eXploration (MMX) mission from JAXA will be launched to the Martian Moons Phobos and Deimos to investigate their nature and improve our understanding of their formation. In 2029 samples from Phobos will be returned back to Earth as MMX is the latest JAXA’s sample return mission. Samples returned to Earth by the MMX mission will be retrieved by JAXA and transferred to the JAXA ISAS Sample receiving laboratory for initial description, followed by initial proprietary analyses performed by the MMX Science Sub-Teams (SSTs), which will include a number of ESA-appointed MMX participating scientists from ESA Member States. The duration of these activities is determined by the MMX Sample Allocation Committee (SAC), and it is estimated to last approximately one year. It is planned that JAXA will thereafter transfer an allocation of samples to ESA for use by scientists and laboratories in the ESA Member States. Sample Curation Facilities (hereafter SCFs) at the German Aerospace Centre (DLR) and at the National Centre for Space Studies (CNES) will host and handle the MMX Samples provided to the ESA Science Program. After transfer to the SCFs the samples will be catalogued (if not done by JAXA) in preparation for an ESA Announcements of Opportunity (AOs) to allocate the Samples to scientists and laboratories in the ESA Member States. In preparation to this major effort, we are working on the setup of an analytical and curation facility in Berlin, in cooperation between the DLR and the Museum für Naturkunde (MfN). Within the analytical facility it will be possible to carry out the basic characterization of the samples in controlled environmental conditions, for then being able to move on to more specialized facilities for more in depth examination. The curatorial expertise is being developed on the existing expertise from the Meteorite Collection based at the MfN and in collaboration with the JAXA curation facilities. Current curators, together with the younger generation are being trained and working on skillset exchange

Bridging the gap - linking remote sensing, in-situ and laboratory spectroscopy

Sample return provides us with “ground truth” about the visited body, verifying and validating conclusions that can be drawn by remote sensing (both Earth-based and by spacecraft) and via landed instruments on other bodies. The detailed investigation of the mineralogy and geochemistry of Ryugu plays a fundamental role in the understanding of its formation processes, and thereby gather further knowledge about the building blocks of the solar system. Based on the preliminary data from remote sensing measurements and laboratory-based measurements, Ryugu is rich in hydrated carbonaceous chondrite (CC) like material and more specifically it is very similar to Ivuna-like (CI) carbonaceous chondrites [1]. These meteorites are characterized by a high abundance of phyllosilicates and organic matter [2], which makes them have a low albedo. However, Ryugu seems to be even darker than CIs, as well as being more porous and fragile [1]. Back in August 2022, the Institute of Planetary Research at DLR (Berlin) received a fragment retrieved by the Hayabusa2 mission from asteroid Ryugu. The fragment assigned to us for analyses is sample A0112, from chamber A. Our investigation is based on two main goals. The first goal is to address a fundamental challenge in the interpretation of remote sensing data which was seen during the initial analysis of the Hayabusa 2 samples. Observations of planetary surfaces using spectroscopy have shown subdued contrast compared to measurements performed under laboratory conditions on analog materials. A strong focus of the work performed at PSL over the last decade has been to understand - and if possible minimize – the difference between laboratory and remote sensing observations (e.g. [3, 4, 5, 6]). Simulating the conditions on the target body as well as accurately reproducing the observing geometries have gone a long way towards that goal, however differences remain. A suggested explanation is the difference between terrestrial analog materials including even meteorites and the surfaces of planetary bodies. With Ryugu samples this hypothesis can be tested further, leading to a deeper understanding of the link between laboratory and remote sensing observations and thus benefiting not only the analysis of Hayabusa 2 data but of all remote sensing observations of planetary surfaces using spectroscopy. The second goal building on this is an investigation of the mineralogy and organic matter of the samples collected by Hayabusa 2, to better: a) understand the evolution of the materials characterizing asteroid Ryugu and therefore advance our knowledge of the mineralogy of the protoplanetary disk and organic matter (OM); b) investigate the aqueous alteration that took place in the parent body that lead to its current chemical and mineralogical characteristics; c) compare the results with data collected from pristine carbonaceous chondrite meteorites rich in hydrated minerals and organic matter