20-EPN-61: Life in extreme environments: Distribution and importance of far-red light driven photosynthesis to primary production in Martian-like environments

Visit by Dennis Nürnberg, Freie Universität Berlin, (Germany) and Daniel Canniffe, Liverpool University (UK) to TA1.5 Makgadikgadi Salt Pans (Botswana).
Dates of visit: 10-19 February 2022

The aim of this project was to confirm the richness and abundance of chlorophyll f-containing cyanobacteria, and their ability to use low-energy light to perform oxygenic photosynthesis in Martian-like environments. This study was a follow-up to a 2019 sampling trip to the sabkhas of the Western Sahara (Morocco), for which we could show that chlorophyll f-cyanobacteria are highly abundant. Here we expanded this research by collecting samples from the hypersaline environments of the Sua and Ntwetwe Pans in Makgadikgadi (Botswana). Microbial mat and rock samples containing endolithic and hypolithic phototrophs were collected. Light microscopy on site confirmed the abundance of cyanobacteria of various morphologies in most collected samples. The microbial mat samples were especially rich in cyanobacteria, forming a 1-2 mm thick layer at various depths depending on the absorption properties of the top layer.

Preliminary analyses with high-performance liquid chromatography (HPLC) in combination with hyperspectral confocal fluorescence microscopy confirmed the presence of red-shifted chlorophylls in some of these samples but to less extent as observed in the sabkhas. Genomic DNA has been extracted and will be used for sequencing and phylogenetic analyses based on 16S rRNA and specific far-red light genes. This will allow to fully evaluate the microbial diversity and their ability to perform chlorophyll f-driven oxygenic photosynthesis. In addition, the enrichment and isolation process of new chlorophyll f-containing cyanobacteria has been started by transferring the samples to growth media of various salinity and keeping them under selective far-red light illumination.

Report Summary:

Read full report, published with kind permission by Dr Nürnberg and Dr Canniffe.

21-EPN-FT1-026: Biogeochemical cycling in the lake systems of the Argentinian Puna: Biogeochemical cycling in the lake systems of the Argentinian Puna: An investigation into the microbial communities of an exceptional Hesperian martian analogue

Visit by Ben Tatton, The Open University (UK) to TA1.6 Argentinian Andes (Argentina).
Dates of visit: 17-26 April 2022

Report Summary: Fieldwork undertaken as part of the Europlanet fast track funding call took place between 16/04/22 and 26/04/22 as part of an international team of scientists from The Open University, The Università degli Studi della Tuscia, and The Universidad Nacional de Córdoba.

Fieldwork was conducted at two high-altitude Andean Lake (HAAL) sites, Laguna Negra, and Laguna de Antofagasta. The focus of the research was to collect sediment cores and water samples from Laguna de Antofagasta to assess how microbial communities change as a factor of depth within the sediment. During the trip, a total of 5 x 30 cm cores, 5 x 250 ml of lake water for culturing, and 15 x lake water samples for geochemical analysis were collected. Furthermore, environmental variables were taken with pH, temperature, conductivity, redox potential, and UV monitored. The trip was a resounding success with enough samples taken to permit the progression of my PhD. The data gained from the trip will contribute to two or three data chapters. These chapters will focus on the geochemical characterisation of the site, the microbiology of the site, and potentially simulation experiments which will focus on Noachian/Hesperian Mars relevant metabolisms. We expect to find that LDA is a suitable geochemical analogue for Gale Crater during the Noachian Hesperian transition. We also expect that the types of metabolisms found within the sediments are similar to those predicted to have been present on Noachian/Hesperian Mars.

20-EPN2-020: Towards prospecting ore deposits on Mars: remote sensing of the planetary field analogue in the Rio Tinto mining area, Spain.

Visit by Jakub Ciazela and Dariusz Marciniak, Institute of Geological Sciences, Polish Academy of Sciences (Poland) to TA1.2 Rio Tinto (Spain).
Dates of visit: 17-27 March 2022

Report Summary: The Rio Tinto area hosts the largest known volcanogenic massive sulfide deposits on Earth. We have investigated 614 sites along a river bed (Fig. 1) located 3 m from each other. At each site, we investigated 5 random samples for pyrite content. The pyrite content was always estimated by 2 to 4 researchers, and the average for each site was computed. The average pyrite content in the entire investigated area is 7.0 vol.% (12.6 wt.%). We have observed two fields, 30 x 30 m, and 30 x 60 m, with average pyrite contents >50 wt.%, which should be suitable for its detection from the orbit, both with Sentinel-2 (field resolution of 10 m) and Landsat (30 m). Principle Component Analysis of the obtained spectra from Sentinel-2 (Fig. 2) gives similar results to mineralogical data we have retrieved in the field during our geological mapping.

By establishing our test field for remote sensing of sulfide deposits in a planetary field analog on Earth, we will be able to determine abundance thresholds for the detection of major sulfide phases on Mars and identify their key spectral features. Our results will help in 1) more efficient use of the current NIR Martian spectrometers to detect ore minerals and 2) designing new space instruments optimized for ore detection to include in future missions to Mars such as one developed at the Institute of Geological Sciences and the Space Research Centre of the Polish Academy of Sciences called MIRORES (Martian far-IR ORE Spectrometer).

Read full scientific report with kind permission of Jakub Ciazela.

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20-EPN2-015: In-situ measurement and sampling of biosignature-hosting products in support of organics detection in the context of ExoMars/2022: In-situ measurement and sampling of biosignature-hosting products in support of organics detection in the context of ExoMars 2022

Visit by Marco Ferrari and Simone De Angelis, IAPS-INAF (Italy) to TA1.2 Rio Tinto (Spain).
Dates of visit: 11-16 July 2022

Report Summary: This project aims at sampling and performing a wide set of VIS-NIR field measurements of weathering products (e.g., sulfates, clays), rocks with hydrothermal origin, and deposits showing evidence of biosignatures. To achieve this goal, during our visit we performed 195 measurement spots with the FieldSpec 4 portable spectrometer in the range of 0.35-2.5 µm and collected 47 samples in different forms. Among all the collected samples, three of them are consistent rock blocks. This is because they will be used as a test for the laboratory model of the Ma_MISS instrument that will be able to drill them and perform the spectroscopic measurements in the borehole wall.

This campaign will also allow us to confirm the capability of the Ma_MISS instrument to detect spectral signatures of organics in geological samples containing bi_osignatures. With the spectroscopic data obtained in the field and the laboratory on the collected samples, we will build a spectral database that will be useful to the scientific community.

These activities on terrestrial analogs have proven useful for understanding life in extreme conditions and how these can be preserved in the form of biological signatures and detected by the scientific instruments that will be on board future missions to Mars.

In addition, this work helps in acquiring crucial preparation for the exploitation and interpretation of the scientific data that the Ma_MISS instrument will provide during the active phase of the mission.

Read full scientific report with kind permission of Marco Ferrari.

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20-EPN-008: Characterisation of a new type of extraterrestrial material through the study of Cumulate Porphyritic Olivine cosmic spherules

Virtual visit by Steven Goderis, Vrije Universiteit Brussels (Belgium) to TA2 Facility 21 – OU NanoSIMS 50L (UK).
Dates of visit: 4-25 October 2021

Oxygen isotopes are a powerful tool to determine the parent bodies of cosmic spherules, which are the entirely melted endmember of micrometeorites. After considering the fractionation processes affecting their original oxygen isotope signatures, >90% of cosmic spherules larger than 200 μm appear to be related to chondrite clans established studying chondritic meteorites.

About 10% of cosmic spherules that show clear chondritic major element compositions display unusual ¹⁶O-poor oxygen isotopic compositions that are not linked to chondritic material present in present-day meteorite collections. Simultaneously, a subset of porphyritic (Po) cosmic spherules labelled Cumulate Porphyritic Olivine (CumPo) particles exhibits textures testifying to the settling of olivine crystals during atmospheric deceleration. This unusual texture suggests these particles entered the Earth’s atmosphere at velocity of ⁓16 km s^-1 , which corresponds to orbital eccentricities >0.3 and is considered higher than most asteroidal dust bands. 

By establishing a potential link between the CumPo particles and a subset of the ¹⁶O-poor spherules and characterising relict mineral grains in a selection of particles from the Sør Rondane Mountains and Larkman Nunatak micrometeorite collections using the Open University NanoSIMS, a parentage with the newly defined CY carbonaceous chondrite group is proposed. This implies that about 10% of the cosmic spherules reaching the Earth’s surface have a near-Earth origin. As such connection is rare in the meteorite collection, demonstrating the importance of fully characterising the flux of micrometeorites to understand the composition of the Solar System.

Read the full scientific report, with kind permission from Steven Goderis.

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20-EPN2-030: The O-isotope signatures of aqueously altered micrometeorites – probing the CO-CM gap and the diversity of C-type asteroids

Virtual visit by Jacopo Nava, University of Padova (Italy) to TA2 Facility 21 – OU NanoSIMS 50L (UK).
Dates of visit: 6-26 July 2022

Report Summary: The flux of extraterrestrial material falling to Earth is dominated by micrometeorites. They originate from asteroids and comets and their analysis provides a complementary perspective to the insights obtained from the study of larger meteorites and from space mission sample returns. Oxygen isotope compositions can be used to match micrometeorites to parent body sources based on distinctive δ¹⁷O and δ¹⁸O ratios.

We studied a population of seven giant Antarctic micrometeorites using high-precision, spatially resolved oxygen isotope analyses to measure the composition of fine-grained matrix in hydrated and dehydrated micrometeorites. 

A characteristic feature of all micrometeorites was large intrasample isotopic variation (>15‰ in δ¹⁸O). In addition, most particles could be matched to known meteorite groups, including identification of CM, CV, CR and, potentially CY parentage. This is consistent with petrographic studies which conclude that the micrometeorite flux is dominated by material from hydrated carbonaceous chondrite asteroids. One particle (TAM5-30) has petrographic characteristics intermediate between the CO and CM chondrite groups. Oxygen isotope analyses of its fine-grained matrix plot either in the CO or CM chondrite fields. This particle is interpreted as a CO-like C2 ungrouped chondrite and may represent material from an otherwise unsampled parent body.

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20-EPN2-018: Structure of the radiocarbon calibration curve around Miyake effect in 660 BC, AD 775 and AD 994

Visit by Andrzej Rakowski, Silesian University of Technology (Poland) to TA2 Facility 16 – Carbon-14 Dating AMS Laboratory (Hungary).
Dates of visit: 6-26 July 2022

Report Summary: Evidence of a rapid increase in the radiocarbon concentration of the tree rings for the year 775 CE was initially presented by Miyake et al in 2012 (henceforth called M12). Since then, other events similar to the M12 have been confirmed for different periods. This project aims to provide new information about the increase in concentration of radiocarbon in the period of abrupt solar activity. For the study we have chosen the periods in XI^th and XIII^th century CE and in VII^th century BCE, in which increase of radiocarbon concentration was noted. The samples have been collected from dendro-chronologically dated trees, and the annual rings has been extracted for measurement.

During the Europlanet TA visit in the Isotoptech Zrt. AMS laboratory, all the samples were prepared to be measured using MICADAS AMS system. Each set of measurement was accompanying with standardsamples (of known radiocarbon concentration) to control the quality of the measurement. To obtain high precision (<2 ‰) the measurement time was extended. The results show occurrence of Miyake events in analyzing periods. For the analyzing period in VIIth century we were able to determinate the occurrence during the year, by dividing the annual ring into three parts early-wood, early-late wood and late wood. During the TA visit we have possibility to learn about the procedures used in the laboratory to prepare samples (of different kinds) for radiocarbon measurement using AMS system. We had a fruitful discussion on possible future cooperation, including joint submission of a research project proposal.

Read full scientific report, with kind permission by Andrzej Zbigniew Rakowski.

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20-EPN2-025: Determining the C-14 ages of offshore groundwater by analysing fluid samples with small quantities

Visit by Nai-Chen Chen, University of Stockholm (Sweden) to TA2 Facility 16 – Carbon-14 Dating AMS Laboratory (Hungary).
Dates of visit: 14-25 March 2022

Report Summary: Submarine groundwater discharge (SGD) has been shown to be an important mechanism in transporting solutes from the terrestrial to the marine environment. Despite being a well-documented process, our knowledge about the timing of offshore groundwater emplacement is extremely scarce. We aim to develop an age-dependent numerical model in our study area to investigate the relationship between SGD and the carbon cycle, whereby the obtained ¹⁴C age of the groundwater is used as a constraint. Our goal is to analyze all the carbon pools present in our cores (i.e. TIC, TOC, DIC and CH₄) for ¹⁴C, so that we can correct for possible interference with the ¹⁴C-DIC signal (used for groundwater age). This is a challenge however, as the carbon content for some of these samples is extremely low.

During this two-week visit, we not only learned about the ¹⁴C preparation methods and operation of Accelerator Mass Spectrometry (AMS), but also discussed and exchanged ideas with Isotoptech AMS C-14 group scientists. Preliminary ¹⁴C results indicate that ¹⁴C depleted DIC is observed closer to the sediment-water interface for cores with anticipated SGD. This can be explained by the advective upwards transport of older groundwater. The discrepancy between the TIC and TOC ¹⁴C content at similar core depths was found to be very large, indicating that these carbon pools are affected by different processes. This mismatch might be a result of the precipitation of authigenic carbonates or microbial activity. 

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20-EPN2-033: An experimental study of bromine partitioning between olivine, orthopyroxene and silicate melt

Visit by Bastian Joachim-Mrosko, University of Innsbruck (Austria) to TA2.15 ETH Zurich Geo- and Cosmochemistry Isotope Facility (Switzerland).
Dates of visit: 04-18 February 2022 and 13-21. April 2022

Report Summary: The heavy halogens are excellent tracers for volatile transport processes in the Earth’s mantle. Our understanding of their budget and distribution is, however, very limited due to their extremely low abundances in the most abundant upper mantle minerals and a lack of well-defined partition coefficients that describe their behaviour during partial melting of the Earth’s mantle.

In this project, we analysed the bromine concentration in minerals and melts of samples, which were produced during high-P-T experiments that simulated partial melting of the Earth’s mantle at Mid-Ocean-Ridge-Basalt and Ocean-Island-Basalt source regions. For this, the neutron irradiation technique was applied, which produced ^80,82Kr from ^79,81Br. This technique results in unmatched detection limits below the ppm-level for the determination of bromine concentrations in nominally anhydrous minerals. During the analysis, regions of interest in the respective samples were ablated with a UV-VIS-Laser at a 10s of micrometer scale. Afterwards, the noble gases were separated and analysed with the “Albatros” mass spectrometer at ETH Zürich. This allowed us to determine bromine concentrations in the melt and in individual olivine and orthopyroxene crystals.First results show that bromine indeed behaves very incompatible with first estimates of bromine partition coefficients between minerals and melt being well below 10^-3. In addition, olivine seems to be the main carrier for the heavy halogens in the Earth’s upper mantle.

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21-EPN-FT1-015: Characterising electron impact induced UV-Optical emission of simple molecules relevant to atmospheres of small Solar System bodies

Visit by Steven Bromley, Auburn University (USA), to TA2 Facility 13 – Electron Induced Fluorescence Laboratory (Slovakia).
Dates of visit: 25 July – 08 August 2022

Report Summary: The goal of the 2022 visit was to study and measure the electron-impact induced emission from dissociation and/or ionization of CO and CO₂ between 0 – 100 eV electron energy. These experiments are part of a longer-term plan to characterize the electron-impact-induced emission features of oxygen-containing molecules found in cometary environments. These data are expected to be used in future modelling and analyses of data acquired in situ during the Rosetta mission to comet 67P/Churyumov-Gerasimenko. We aim to understand the conditions in the inner coma and how electron-impact-induced emission features can probe the physical and chemical processes occurring in the near-nucleus coma environment.  

During the first half of the visit, we measured electron-impact spectra of CO₂ gas at multiple electron energies. Electron impact of CO₂ can give rise to emission from CO, CO⁺, CO₂⁺, and excited states of C and O atoms. Since the probabilities of the different reaction channels depend strongly on the collision energy, these spectral features offer a way to diagnose the conditions of plasmas containing CO₂. The collected spectra and threshold measurements are in reasonable agreement with the limited data in the literature. During the second half of the visit, we measured electron-impact spectra of CO gas at numerous electron energies. Many of the spectral features for neutral CO, CO⁺, and atomic C and O were characterized, as a function of electron energy, for the first time. Given the time-consuming nature of the measurements, data analysis and additional measurements will continue remotely. 

Full Scientific Report on the TNA visit

Dissociative electron impact excitation reactions can provide a remote diagnostic of neutral gases and the physical environment of atmospheres around planets and small bodies in our solar system. The spectral signatures of the excited collision products are unique to each species and span the UV, visible, and infrared ranges. Previous experiments on electron impact of H₂O (Bodewits et al 2019) showed clear spectral differences between photo-excitation, photodissociation, and electron impact collisions with water vapour. The efficiency of the electron impact dissociative & ionizing excitation, determined by the energy-dependent cross section, provides a remote diagnostic of the emitters in astrophysical plasmas. This process and its unique spectral signatures have been used to confirm a tenuous O₂ atmosphere around Callisto, in the near-nucleus coma of comet 67P/Churyumov-Gerasimenko, and the atmosphere of Ganymede (Roth et al. 2021).

In electron impact, CO₂ produces strong emission from its cation, CO₂⁺ (Ajello 1971b), and both CO and CO₂ produce strong emission from the “Comet Tail Bands” of CO⁺ (Ajello 1971a). At lower collision energies beneath the threshold of CO⁺formation, the Cameron bands of CO (ultraviolet wavelengths) are excited, and electron impact collisions have been inferred from UV observations of the Cameron bands in the atmosphere of Mars (Ajello et al 2019). In most comets, CO₂ and CO are second in abundance to water vapour. Both CO and CO₂ have lower sublimation temperatures compared to H₂O, and can sublimate from cometary nuclei at large heliocentric distances. The threshold of the strongest electron-induced emission of these species (either CO₂⁺ from CO₂, or CO⁺ from CO) are relatively low and can be excited in the comae of comets at large heliocentric distances. Compared to their neutral counterparts, these cations emit in wavelength ranges that are accessible from ground-based observatories. Thus, these species are of particular interest to planetary and cometary science.

During our visit to the EIF lab at Comenius University, we focused on measuring (1) the electron-impact induced emission spectra of the gases CO and CO₂ and the excited collision fragments, and (2) the emission cross sections for the important spectral features. For (1), we set a fixed electron beam energy and scanned the CCD camera across the spectral range of interest. A sample of our collected spectra is shown in Figures 1 & 2, which show the electron-impact spectra of CO₂ and CO at 50 eV electron energy. At 50 eV, almost every feature in the CO₂ data can be identified as bands of the cation CO₂⁺. In the CO spectrum (Fig. 2), the strongest features are from the cation CO⁺. We also measured the spectra at multiple electron beam energies below and above known thresholds (e.g. the threshold for CO⁺ formation, ~17 eV, 100 eV), and we identified emission bands of neutral CO. These bands are well-characterized in the ultraviolet beneath ~300 nm, but many of the emission cross sections for features at visible/near-IR wavelengths are not available. In many cases, cross sections are limited to a single value, typically 100 eV electron beam energy. The spectra also show emission lines of atomic O and atomic C in the near-IR. 

For (2), measuring absolute cross sections, we adopted a systematic procedure. Using the overview spectra, we deduced the most probable identifications of the spectral features. With the photon detector set at a fixed wavelength, we scan the electron beam energy to measure relative cross sections, which will later be normalized and scaled to precisely known emission cross sections in literature. Interestingly, many of the molecular bands in the spectra have multiple thresholds, as shown as by the measured relative cross section of the CO₂⁺ feature (Figure 3). In a similar measurement of a CO⁺ Comet Tail band (455 nm, Figure 4), our measured thresholds are consistent with data available in literature. For both sets of experiments (CO and CO₂), the spectra were far richer in features than anticipated. While we are able to identify many features by comparison to theoretical models and other experiments, the cross section measurements for every feature could not be completed in a single visit. We will continue to collaborate with the EIF laboratory remotely to measure the remainder of the cross sections. It is expected that a manuscript detailing our cross section measurements on CO and CO₂ will be submitted to the Astrophysical Journal Supplement Series in the coming year. 

References

1. D. Bodewits et al 2019 ApJ 885 167
2. Roth, L., Ivchenko, N., Gladstone, G.R. et al. 2021, Nature Astronomy 5, 1043-1051. 
3. M. Ajello, 1971a, The Journal of Chemical Physics, 53, 7.
4. M. Ajello, 1971b, The Journal of Chemical Physics, 53, 7.
5. Ajello et al 2019, Journal of Geophysical Research: Space Physics, 124, 2954-2977

Figure 1: Measured electron impact-induced emission spectrum of CO₂ gas at 50 eV electron energy with a 100 micron slit size. Faint atomic features are visible in the near-IR. The emission between 280 and 500 nanometers is primarily from the cation CO₂⁺.  

Figure 2: Measured electron impact-induced emission spectrum of CO gas at 50 eV electron energy with a 400 micron slit size. Faint atomic features are visible in the near-IR. The emission between 300 and 650 nanometers is primarily from the cation CO⁺.  

Figure 3: Measured relative emission cross section of the blended CO₂⁺ / CO⁺ band at 428.3 nm from electron impact of CO₂ gas. Multiple thresholds are visible in the cross section as a function of collision energy, indicating that the feature is a likely blend of CO₂⁺ and CO⁺ emission bands. The thresholds are consistent with theoretical values calculated from the known dissociation and excitation energies. 

Figure 4: Relative emission cross section of a CO⁺ comet tail band (455 nm) from electron impact of CO gas. The threshold of CO⁺ emission (16.74 eV) is consistent with the value in the literature within the experimental uncertainties.  

Figure 5: Visiting postdoc Steve Bromley and PhD student Barbora Stachova discussing the electron impact spectrum of CO gas at 100 eV electron beam energy. 

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20-EPN-060: Characterise UV-Optical emission by conducting electron impact reactions on molecules relevant to the atmospheres of small bodies in our solar system

Virtual visit by Dennis Bodewits, Auburn University (USA), to TA2 Facility 13 – Electron Induced Fluorescence Laboratory (Slovakia).
Dates of visit: 21-29 July 2022

Report Summary: Auroral emissions from electron impact processes provide the opportunity to remotely characterize the physical properties of plasma and neutral gases surrounding small bodies. Surprisingly, Rosetta found that outside 2 AU, atomic and molecular emission features in the inner coma were predominantly caused by dissociative electron impact excitation. These emission features provide a wealth of information on local plasma conditions and through excited fragment species, it can allow for the measurement of chemical abundances of species that may otherwise not be easily detected remotely (CO2, O2).

We conducted electron impact experiments at the electron induced fluorescence laboratory at Comenius University (Bratislava, Slovak Republic) to characterize electron-impact induced emission of fragment species in the neutral gas surrounding comets and other small bodies in our solar system. For this project, we studied collisions between electrons up to 100 eV and CO2 and CO molecules. We measured velocity-dependent emission cross sections, determine activation thresholds of relevant reactions, and construct a spectral atlas that will aid observers and astrophysical modelers.

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20-EPN2-069: Challenging the adaptability of an anhydrobiotic cyanobacterium to Mars-like conditions

Visit by Beatriz Gallego Fernandez, University of Rome Tor Vergata (Italy), to TA2 Facility 6 – DLR Planetary Simulation Laboratory (PASLAB) (Germany).
Dates of visit: 21-29 July 2022

Report Summary: Different studies reported the endurance of cyanobacteria to Mars-like conditions; however, little is known about the cellular and molecular mechanisms responsible for this resistance. The further combination of Martian UV fluxes and perchlorate ions at concentrations found on the surface of Mars increases the challenges for survival. Under this context, this study aimed to investigate the adaptability and cellular responses of metabolically active biofilms of Chroococcidiopsis CCMEE 029 to Martian surface-like conditions combined with perchlorate ions.

Biofilms obtained from cells mixed with two different Martian regolith analogs and 2.4 mM of perchlorate ions on top of an agarized regolith-based medium were exposed to unprotected Mars-like conditions for 3 days. Parameters consisted of a Mars-like atmosphere (95% CO₂, 4% N₂, 1% O₂) constant pressure of 700 Pa, periodic photosynthetically active radiation (PAR, 400-700nm, 3W/ m²/s) and UV (4W/m²/s) irradiation for 16 h followed by 8 h of dark with diurnal cycling of relative humidity and temperature from 75% to 0% and +15ºC to -50ºC respectively. The photosynthetic yield was followed during the exposure with the Mini-PAM analyzer integrated into the Martian simulation chamber. Post-exposure analyses of cell-viability assessment, CFU capacity, and pigment autofluorescence and morphology will be performed. Proteomics analyses are ongoing in collaboration with Dr. Peter Lasch from the Robert Koch Institute, Berlin (Doellinger et al. 2020).

Overall, this study will contribute to extending our appreciation of the limits of life as we know it, from the habitability of Mars to future management of Life Support and In-Situ Resource Utilization systems.

Read the full scientific report, with kind permission by Beatriz Gallego Fernández.

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20-EPN2-048: Heating effects on the spectral reflectance properties of carbonaceous chondrite meteorites

Visit by Edward Cloutis, University of Winnipeg (Canada), to TA2 Facility 5 – DLR Planetary Spectroscopy Laboratory (Germany).
Dates of visit: 28 August -2 September 2022

Report Summary: Carbonaceous chondrites are likely derived from dark (C-class) asteroids. Sample return missions to dark asteroids (JAXA Hayabusa-2, OSIRIS-REx) will allow us to link specific meteorites to these possible parent bodies. The compositions of the sample return target asteroids (Ryugu and Bennu) are currently unknown, as are the compositions of other dark asteroids. Dark asteroids are important scientific targets because they may have delivered prebiotic organic molecules to the early Earth.To help address how we can determine the compositions of dark asteroids, particularly whether they are primitive, aqueously-altered, and/or heated, we conducted a series of experiments at PSL designed to address this.

Specifically, we performed heating experiments, in vacuum, on clay minerals present in carbonaceous chondrite meteorites, and measured their subsequent spectral reflectance properties, as well as on samples heated in previous experiments (clays, carbonaceous chondrites, carbonaceous chondrite analogues), focusing on the most diagnostic spectral feature relevant to dark asteroids – the 3 micron region hydroxyl/water absorption band. The results are still being analysed, but it appears that heating in vacuum and exposure to vacuum cause changes in the depth and shape of this absorption feature, as well as the albedo, spectral slope, and appearance of additional absorption features. The results of this study will provide important constraints into the composition and history of dark asteroids.

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20-EPN2-042: Investigation of type 2 ungrouped carbonaceous chondrites to shed light on their origin, formation, and evolution

Visit by Mehmet Yesiltas, Kirklareli University (Turkey) to TA2 Facility 5 – DLR Planetary Spectroscopy Laboratory (Germany).
Dates of visit: 27 June -1 July 2022

Report Summary:

In the TA call 2 of the Europlanet 2024 framework, both hemispherical and bidirectional
reflectance spectra were collected on a total of 13 meteorites. For each meteorite, spectral data were recorded between 0.2 μm and 25 μm.

The analysed meteorite samples included carbonaceous chondrites as well as non-
carbonaceous chondrites that contain carbonaceous clasts and phases. The meteorites
were measured as bulk, and the same 2 mm diameter for the incoming beam aperture was
used. These measurements and their results will provide additional insights on the infrared spectra of meteorites and their carbon content, which will help us better understand and constrain the composition of their respective parent asteroids.

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