20-EPN2-035: Characterisation of the composition and metabolic profiles of microbial communities in Antarctic dry soils as a model for Mars explorations

Visit by Fabiana Canini, University of Tuscia (Italy) to TA2.19 Center for Microbial Life Detection, Medical University Graz (Austria).
Dates of visit: 4-8 October 2021

Report Summary: McMurdo Dry Valleys (MDVs) of Antarctica, the coldest and driest desert on Earth, characterised by strong UV irradiation and strong winds, are considered one of the closest terrestrial analogue of the Martian environment. Only microbial life-forms inhabiting the rocks and soils can survive in these harsh conditions. Endolithic communities have been thought to be the predominant life forms and have been widely characterised, while the drivers of microbial colonisation in MDVs dry permafrost are still barely known. It is still not clear if life forms found in soils through molecular approaches are metabolically active or present as dormant wind-transported spores, propagules or death cells.

Additionally, the possible contribution of the endolithic communities to soils diversity has never been investigate in MDVs. As the endolithic growth has been hypothesised as one of the adaptive
strategies of putative Martian microbial life-forms, the hypothesis of rock fragments dispersal should be investigated, to give new perspectives on life-traces search on Mars.

The microbial diversity and metabolic activity have been characterised in soils collected in MDVs at increasing distance from a colonised sandstone outcrop and in the corresponding rocks samples. The microbial composition and functionality have been investigated through shotgun metagenomics, while the metabolomics profiles have been defined through NMR metabolomics. This description may give unprecedented information on whether the cells found are active or not and on how they metabolically adapt and thrive in this environment. The results may be useful in the frame of search for chemical biosignatures within future Mars explorative missions.

Read the full scientific report with kind permission of Fabiana Canini.

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.

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.

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

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. 

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.

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 ionisation 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 characterised, 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. 

Read the full scientific report, with kind permission by Steve Bromley.

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.

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.

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.

20-EPN-080: Structural organisation and complexity of the Antarctic cryptoendolithic communities

Visit by Gerardo Antonio, Università degli Studi della Tuscia (Italy) to TA2 Facility 3 – NHM Petrology, Mineralogy and Chemistry Facility (UK).
Dates of visit: 15-19 March 2022

Report Summary: The Antarctic cryptoendolithic communities are microbial ecosystems that dominate the biology of most ice-free areas in Continental Antarctica and described for the first time in the McMurdo Dry Valleys, the largest ice-free area of the continent. The Dry Valleys are a nearly pristine environment largely undisturbed and uncontaminated by humans and show remarkable peculiarities, representing an important analogue for the conditions of ancient Earth and Mars and a model environment for astrobiological studies.

These ice-free areas are dominated mostly by oligotrophic mineral soil and rocky outcrops and, for the harshest conditions in this area, the biology is dominated by cryptic microbial life-forms dwelling inside rocks. These cryptoendolithic communities are complex and self-supporting assemblages of phototrophic and heterotrophic microorganisms, including Bacteria, Chlorophyta and both free-living and lichen-forming fungi.

Despite the recent molecular studies to investigate the biodiversity and community composition, the interaction microbes-microbes and microbes-rock matrix, the spatial organisation, rock microstructure (e.g. porosity, pore size and connectivity) are totally unexplored.

We, herein, are proposing to build an interactions network map, on colonized and not colonized sandstone, resolving the contributions of the different microorganisms and the relationships established among them and between microbial cells and the lithic substrate.