Category: TA Call 1

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.

20-EPN-083: Beyond Antarctica: a survey on detection of life in endolithic fossils supporting future space exploration missions

Visit by Federico Biagioli, University of Tuscia (Italy) to TA2.19 Center for Microbial Life Detection, Medical University Graz (Austria).
Dates of visit: 14-20 November 2021 (in person visit), 21-26 April 2022 (remote analysis)

Report Summary: Endolithic growth is the ultimate microbial adaptation and the predominant life-form in the far extreme ice-free areas of Antarctic deserts, considered among of the best analogues of the Martian environment on Earth. Although recent molecular studies have started to shed light on the biodiversity, distribution and composition of crypto-endolithic communities in visibly colonized rock samples, fossilized or apparently not colonized endolithic communities remain largely unexplored. Amplicon-sequencing analysis of fungal and prokaryotic domains on both not colonized and fossil samples were here performed to gain information about preservation of extinct life traces within rock and evidences of possible life detection also in eventual extra-terrestrial samples. Genomic DNA was extracted and sequenced from 24 fossil and 6 apparently not colonized rocky samples, resulting in a high number of reads and mapped ASVs for fungal (657,626 quality- filtered reads and 161 ASVs), bacterial 16S rDNA (1,296,594 reads mapped into 839 ASVs) and 16S archaeal specific (2,813,402 validated clustered in 3,514 ASVs) datasets. The high number of reads and ASVs achieved allows us to suppose that rocks not only represent a perfect refuge from harsh external environmental conditions, but also an important preservation ark for biosignatures of past life forms.

Read the full scientific report with kind permission of Federico Biagioli

20-EPN-014: Ancient oceanic crusts as tracers of terrestrial mantle evolution – Ages and mantle source fingerprints from centimetric mantle eclogite xenoliths

Virtual visit by Sonja Aulbach, Goethe University Frankfurt (Germany) to TA2.1 VU Geology and Geochemistry radiogenic and non-traditional stable Isotope Facility (GGIF).
Dates of visit: 2 June – 05 August 2022

Report Summary: Kimberlite-borne eclogite xenoliths with subducted oceanic crustal protoliths were typically affected by multiple processes during metamorphism and extended residence in cratonic lithosphere.

We acquired precise Nd isotope compositions (¹⁴³Nd/¹⁴⁴Nd) from minute amounts of eclogitic garnet and clinopyroxene derived from centimetric pristine and metasomatised eclogite xenoliths from Orapa, Botswana, originally for insights into their origin, ages and later evolution as part of the continental mantle. Though not yielding any pre-entrainment age constraints, the new data provide intriguing insights into the behaviour of Sm and Nd in the main eclogite constituents during mantle metasomatism.

Unradiogenic and isotopically homogeneous Nd in clinopyroxene from metasomatised eclogites correlates strongly with indicators of metasomatism by kimberlite melt, which also lowered its Sm/Nd ratios. In contrast, garnet has Sm/Nd showing no difference between metasomatised and pristine specimens. Clinopyroxene-garnet two-point isochron ages correlate positively with temperature of the eclogites’ last residence in the mantle, and several metasomatised samples give ages that are younger than the timing of entrainment to the surface and cooling.

These seemingly paradoxical observations can be explained when equilibration mechanisms and crystal-chemical controls are taken into consideration. Volume diffusion at high temperature caused slow Nd isotopic exchange, whereas melt-assisted recrystallisation at low temperature facilitated instant equilibration. Moreover, metasomatised eclogites residing at low temperature contain garnet with lower grossular content, both of which impeded the addition of Nd to garnet, which retained high Sm/Nd. Combined with its isotopic homogenisation, garnet with high Sm/Nd causes flattening of the two-point isochron slope, resulting in geologically implausible young ages.

20-EPN-038: The strange behaviour of highly viscous mud in the low pressure environment: why the mixture changes its volume?

Visit by Petr Brož, Institute of Geophysics of the Czech Academy of Science (Czech Republic) to TA2.20 Open University Mars Chamber (UK).
Dates of visit: 6-17 December 2021

Report Summary: We performed multiple mud experiments inside a low-pressure chamber to investigate whether the volume of mud changes once exposed to the reduced atmospheric pressure of Mars. Our results show that mud extruded onto the surface under martian environmental conditions increases its volume and hence behaves differently than on Earth. The low atmospheric pressure causes instability of the water present in the mud mixture, leading to the formation of bubbles, which increase the volume of the mud.

These bubbles are then trapped within the mud. The buoyancy of the bubbles is not sufficient to overcome the drag force within the viscous material and rise to the surface. Hence, these bubbles remain trapped and gradually grow up to centimetre scale sizes. During their growth they push the mud out of the container resulting in horizontal and vertical inflation of the mud surface over cm-scales.

This behaviour is not observed at terrestrial mud flows, but it is somewhat similar to volumetric changes associated with degassing of some terrestrial lavas or mud volcano eruptions. Our experimental approach hence shows that viscous mud exposed to reduced atmospheric pressure behaves differently to on Earth.

Full scientific report published by kind permission of Petr Brož.

20-EPN-084: Converting one amino acid to the other containing sulfur via ion irradiation : Implication to chemical evolution on Europa surface ices

Visit by Rahul Kumar Kushwaha, Physical Research Laboratory, Ahmedabad (India) to TA2.11 Atomki Ice Chamber for Astrophysics / Astrochemistry (ICA) (Hungary).
Dates of visit: 8-19 December 2021

Report Summary: The non-equilibrium chemistry driven by the charged particle and photon irradiation processes are responsible for the rich chemistry on the surfaces of icy satellites. Among the icy satellites of the Jovian and Saturnian planetary systems, a few satellites such as Ganymede, Europa, Dione, Rhea, Callisto and Titan that are embedded in their respective planetary magnetospheres were observed to undergo rich chemical processes due to the bombardment of a wide range of energetic atomic and molecular ions that are present in their planet’s magnetospheres, which processes the icy surfaces of satellites by irradiation and implantation. Magnetospheres also help in bringing new species from one satellite to the other. Especially in the Jupiter system of icy satellites, sulfur transfer from Io to the other satellites is quite likely. The sulfur ions from Io are picked up by the magnetosphere and are accelerated towards the other icy satellites; Europa being the closest neighbour to Io will be implanted with sulfur ions. The Jovian satellites, due to the presence of the Jupiter’s magnetosphere, are subjected to highly energetic S ion irradiation which leads to a range of chemical activity on their surfaces. In this project, we have studied the effect of S ion irradiation on Aspartic acid for a range of energies at two different temperatures (100 K, 20 K), where the 100 K experiments are aimed to mimic the conditions of Europa. The irradiated residue was then analysed using an optical microscope, scanning electron microscope and liquid chromatography mass spectrometry.

Full scientific report published by kind permission of Rahul Kumar Kushwaha

20-EPN-078: Abrasion test to understand aeolian grain surface evolution on Mars versus Earth – suggestions for ExoMars rover mission

Virtual visit by Zsuzsanna Kapui, Eötvös Lorand University ̷ Research Centre for Astronomy and Earth Sciences (Hungary) to TA2.4 Planetary Environment Facilities (PEF), AU (Denmark).
Dates of visit: 2-6 August 2021

Surface microtextures on quartz grains provide good information of the transport medium (ice, river, wind) on Earth, as shape and surface micromorphological features strongly depend on them. A well-developed system has been already used for the quartz grains, but similar detailed studies of basaltic grains have not been conducted before, although this could be relevant for Mars. We aim to develop such a system for olivine grains (main basalt forming mineral). Between 2-6 August 2021, a quartz and an olivine sand grain group (both sized 1 – 2 millimetre) were analysed by wind transport at the AWTSII Wind tunnel facility in Aarhus, Denmark.

A special, self-built box (wind tunnel section with a relatively small cross section) was designed and produced in Hungary to allow periodic transport of the sand grains from one end to the other by a motor driven rotation system. The test started with difficulty because the sands movement did not start, a combination of factors meant that even at the highest fan rotation rate of the AWTSII facility active sand transport was not achieved. Finally, the solution became that the sand holder box in the wind tunnel was also tilted by 24 degrees. The quartz and olivine sands were transported by a mixture of gravitational avalanching and wind driven transport at around 1 bar pressure. Altogether two tests were performed during around four hours to see the attrition process related to grain shapes and surface microstructures. Microscope and webcam videos as well as wind flow data (pitot tube) were collected.

Currently, microscopic analysis with Morphology instrument is underway on the returned particles. The obtained results will be included in an article in progress and in my doctoral dissertation.

20-EPN-050: 26-Aluminium-26-Magnesium systematics of chondrules and clasts in unequilibriated ordinary chondrites

In-person visit by Audrey Bouvier (Universität Bayreuth, Germany) to TA2.9 Ion probe facility (IPF), CRPG (France).
Dates of visit: 7-11 June 2021

Chondrules are a major component of chondritic meteorites whose time and mechanism of formation are still debated. Inconsistencies in formation ages of chondrules have been found between ages determined by the absolute Pb-Pb chronometer or using the relative ²⁶Al-²⁶Mg chronometer. While the Pb-Pb ages suggest that chondrules formed continuously for about 4 Ma from the time of CAI formation, the ²⁶Al-²⁶Mg data show evidence that chondrules did not form until about 1.8 Ma after CAIs. One possible explanation could be a heterogeneous distribution of ²⁶Al in the solar nebula.

To evaluate this hypothesis, we used secondary ionization mass spectrometry (SIMS) to date chondrules and clasts from unequilibrated ordinary chondrites with the ²⁶Al-²⁶Mg chronometer. Three chondrules from ordinary chondrites show resolvable excesses in ²⁶Mg due to the decay of ²⁶Al and formed around 2 Ma after CAI formation, consistent with previous studies. Analysis of a large igneous inclusion from Paposo 004 supports a formation age within 1 Ma after CAI. The presence of a relict olivine chondrule in this inclusion provides contextual evidence that chondrule formation must have taken place prior to this time.

20-EPN-005: Cosmic-ray-induced chemistry in pure ices

Virtual visit by Alexei Ivlev, Max Planck Institute for Extraterrestrial Physics (MPE) (Germany) to TA2.11 Atomki Ice Chamber for Astrophysics / Astrochemistry (ICA) (Hungary).
Dates of visit: 23 February – 05 July 2021

Report Summary: The principal aim of the project was a dedicated study of generic effects induced in pure astrophysical ice analogs due to their bombardment by cosmic rays with energies E in the vicinity of the maximum of electronic stopping power. It is known that the energy of ejected electrons, which are produced in primary ionization events, has a significant dependence on E in this energy range. 

Thus, by selecting pairs of beam energies on both sides of the Bragg peak, such that the corresponding stopping-power values are equal, we were able to probe the effect of electron-impact excitations of ice molecules. We selected CO films as the best irradiation target, for which the biggest variety of radiolysis products was expected and the most detailed predictions of chemical models were available. 

We found that the first radiolysis products, detected at the astrophysically relevant values of ion fluence, are very different from predictions of chemical models. At the same time, the reaction kinetics shows no statistically significant difference between ion beams of same stopping power. This rules out the importance of electron-impact excitation in radiolysis chemistry of CO, and suggests that this process may generally be negligible compared to the chemistry driven by CR heating (determined by the stopping power value). On the other hand, by comparing the sputtering yields measured for beams of same stopping power, we discovered a significant asymmetry, with the yield at lower energies being up to a factor of two larger that at higher energies.

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20-EPN-043: A Systematic Study of Sulfur Ion Radiolysis of Simple Oxide Ices.

Visit by Zuzana Kanuchova (virtual participation), Astronomical Institute od Slovak Academy of Sciences (Slovakia) and Duncan Mifsud (in-person participation), University of Kent (UK) to TA2.11 Atomki Ice Chamber for Astrophysics / Astrochemistry (ICA) (Hungary).
Dates of visit: 30 November – 4 December 2020 and 25-29 January 2021

Report Summary: We have implanted 290 keV S⁺ ions in a variety of simple oxide ices, including CO, CO₂, H₂O, N₂O, O₂, and CO:N₂O at 20 K, as well as CO₂ and H₂O at 70 K. Our aim was to determine whether such implantations could result in the formation of sulfur-bearing product molecules, particularly SO₂ which has been detected at the surfaces of several icy Solar System moons. 

The performed experiments suffered from initial setbacks in the form of unexpected and significant sputtering of the astrophysical ice analogues during irradiation. In order to mitigate this sputtering, we made use of two different experimental techinques; (i) via simultaneous deposition and irradiation of the ice analogue in cases where we knew gas phase chemistry to be negligible, and (ii) via creation of a very thick (~3-5 μm) ice and a slow rate of implantation. Once these initial problems were solved, we were able to successfully carry out implantations into the six ices mentioned above. 

Our work has indicated that although sulfur-bearing molecules (such as OCS and H₂SO₄ hydrates) may form as a result of such implantations, SO₂ formation was not detected in most experiments, except at high fluence (~1016 ions/cm²) implantations in CO. Such results have important implications for the icy Galilean satellites of Jupiter, suggesting that the SO₂ present there may be formed by endogenic processes at the lunar surfaces.

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20-EPN-017: LITRASV – Life in TRAvertine-Sinter Veins: a possible key to recognize extra-terrestrial life in tectonically-driven depositional systems.

Visit by Enrico Capezzuoli, University of Florence and Andrea Brogi, University of Bari (Italy) to TA1 – Iceland Field Sites, MATIS
Dates of visit: 04-10 July 2021

Report Summary: Detailed study of travertine and sinter depositional systems and related feeder conduits (veins) in cold desertic setting (Lýsuhóll and Hveravellir sites- Iceland), as possible repository of subsurface life to be observed in extra-terrestrial setting. The performed field activity allows reconstruction of the structural control in these sinter/travertine depositional systems, with stratigraphic-sedimentological characterisation of the travertine-sinter lithofacies. 16 travertine/sinter samples were collected from the two sites, together with the basic physical characterization of the thermal springs (T, pH, Cond). Due to the local conditions, all the collected samples derive from fossil/inactive systems (veins and crusts samples). Among these, one sample derives from a sinter vein recognized in the Lýsuhóll site, while all other derive from fossil vents or close surroundings.

Samples returned to Italy for future petrographic and geochemical characterization in order to detect and define possible organic presence in such an extreme environment.

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20-EPN-032: Radioresistance of aromatic complex organic molecules: nucleobases.

Virtual visit by Hermann Rothard, CIMAP (Caen, F) CNRS (France) to TA2.11 Atomki Ice Chamber for Astrophysics / Astrochemistry (ICA) (Hungary).
Dates of visit: 17 May – 02 July 2021

Report Summary: Complex molecules (including amino acids and nucleobases) can be formed in cold space environments conditions (e.g. dense molecular clouds, outer solar system) by e.g. UV irradiation and ion bombardment of ices containing simple molecules. Consequently, the radiation resistance of such complex molecules in order to determine their survival times in space should be investigated. We therefore studied the radiolysis and radio-resistance of the purine nucleobase (Adenine, two aromatic rings) in solid phase as a function of temperature (20-300 K) with H (0.8 MeV) and He (3.2 MeV) beams at ATOMKI. This first systematic study of the influence of the temperature revealed that Adenine is found to be significantly (of the order of 50%) more radio-resistant at high temperatures. At low temperatures T < 50K, Adenine is more radiosensitive (higher cross sections).

The results are preliminary and analysis is ongoing. Furthermore, we found that the destruction cross sections scales with the electronic stopping stopping following a power law with a stronger than linear dependence.

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