Category: TA

22-EPN3-107: Characterising the electron-impact-induced emission of CS2 to constrain sulfur abundances in cometary and planetary atmospheres

Visit by Steven Bromley, Auburn University (USA), to TA2 Facility 13 – Electron Induced Fluorescence Laboratory (Slovakia).
Dates of visit: 08 – 19 May 2023

The main goals of the 2023 visit were to study the electron impact emission cross sections, spectral features, and dissociation thresholds of CS₂ gas. The products of CS₂ – atomic sulfur and its ions, CS, excited CS₂, and CS₂⁺ – make CS₂ a rich target of inquiry. Further, the products CS and atomic S are routinely observed in near-nucleus observations of comets (see e.g. discussion in Noonan et al. 2023). Measurements of sulfur abundances in comets show discrepancies between remote and in-situ observations, and improved electron-impact data for CS₂ may help resolve this discrepancy. The present experiments are part of a long-term campaign to understand diagnostic electron-impact driven emission and ionization of diatomic/polyatomic molecules in cometary atmospheres. We expect these data will provide valuable insights in one of our ongoing projects to investigate sulfur abundances through analyses of 100+ archived comet observations. In the first week of our visit to the EIF lab, we measured the electron-impact spectrum of CS₂ gas at various electron energies between 0 – 100 eV, with energies chosen based on known thresholds for CS, CS₂⁺, and atomic fragment production. During this time, we also began developing an emission model for CS in order to simplify the future analyses of these data. In the second week of the visit, higher-resolution spectra and several cross sections were measured in order to begin comparisons to existing literature. We also identified, for the first time, the emissions of atomic fragments (S I, S II) in the near-infrared red-ward of 600 nm.

20-EPN2-91: Experimentally determined distribution of highly siderophile elements between sulfide and silicate melts at highly reduced conditions: implications for terrestrial late accretion models

Visit by Edgar Steenstra, Institute of Mineralogy, WWU Muenster (Germany) to TA2.2 VU (Exo)Planetary Interior Simulation Laboratory (PISL).
Dates of visit: 22 – 24 November 2022

Report Summary: Fifteen high-pressure experiments on the PISL end-loaded piston cylinder press were performed at 1 GPa and 1873 K to systematically investigate the effects of Cu and Ni on metal- and sulfide-silicate partitioning of highly siderophile elements (HSE) Pd, Ru, Pt and Ir. Run times at peak conditions varied around 60-90 minutes. The starting compositions consisted of silicate, sulfide and metal powders with added metallic Si. The experimental run products consist of well-segregated metallic and sulfide blobs in a silicate glass. The addition of metallic Si and the initial reduction of the experiments result in the suppression of nugget formation. The glass does contain minute specks typical of S- saturated silicate melts – subsequent LA-ICP-MS measurements of the run products show that these specks do not contain HSE, as initially hypothesized. Electron microprobe and LA-ICP-MS analyses further show that the experimental run products are homogeneous and no compositional zoning was observed. Initial results show that the addition of Cu and Ni to the sulfide liquid decreases the O content of that sulfide liquid at a given FeO value of the silicate melt. This will most certainly affect the partitioning of the elements of interest – preliminary results for Pt confirm this by its variation by three orders of magnitude at a given FeO content. Preliminary results also show that Pd, Ru, Pt, Ir are all preferentially partitioned into the metallic liquid instead of the sulfide melt, confirming their preference for S-poor alloys relative to S-rich liquids. 

20-EPN2-119: Distribution of sulfide-loving elements between major (mafic) mineral phases and silicate melts

Visit by Stephan Klemme and Edgar Steenstra, Institute of Mineralogy, WWU Muenster (Germany) to TA2.2 VU (Exo)Planetary Interior Simulation Laboratory (PISL).
Dates of visit: 22 – 24 November 2022

Report Summary: Twelve high-pressure experiments on a piston cylinder press were performed at 1 GPa and 1673-1873 K to systematically investigate the sulfide-silicate partitioning of chalcophile elements as a function of (non-FeO) silicate melt compositional terms. Run times at peak conditions varied around 70 to 220 minutes. The starting compositions consisted of silicate and sulfide powders. The experimental run products consist of well-segregated sulfide blebs in a silicate glass. The glass contains minute sulfur blebs but subsequent LA-ICP-MS measurements showed that these blebs do not contain the elements of interest and are composed of Fe-S-O.   Electron microprobe and LA-ICP-MS analyses further showed that the experimental run products are homogeneous and no compositional zoning was observed. 

Initial results show that variations in silicate melt composition affect the partitioning of chalcophile elements in a non-ideal way – i.e. FeO activity varies significantly across different melt compositions, thereby affecting the geochemical behavior of the elements of interest. Therefore, it can be expected that in an arc-type differentiation suite the sulfide-silicate partitioning behavior may vary significantly, purely due to variations in FeO activity due to variable silicate melt compositions. 

20-EPN2-009: High-precision oxygen isotope composition of Martian meteorites and their components – insights into the accretion history of Mars

Virtual visit by Siw Egdalen, University of Copenhagen (Denmark) to TA2 Facility 22 – Open University Laser Fluorination Oxygen Isotope Facility (UK).
Dates of visit: 24 May – 11 June 2021

Analyses of Martian meteorites and their components predicts the existence of three main geochemical reservoirs on Mars, namely an enriched crust, a complementary depleted lithospheric mantle, and, lastly, a primitive asthenospheric mantle. Investigating the oxygen isotope composition of these reservoirs is critical for a full understanding of the accretion history of Mars. The Δ17 O composition of ~0.3‰, defined by the SNCs is believed to reflect the primary planetary composition of the martian mantle (1). However, analyses of ancient (>4.5 Ga) individual zircons and minerals from the NWA 7533 regolith breccia, record Δ17 O values that are characterized by a much heavier Δ17 O composition and thus different from the SNCs (2,3). A population of young zircons (<1.5 Ga), also from NWA 7533, are derived from a primitive reservoir located in the deep martian interior, as they are characterized by chondritic-like initial Hf isotope composition (4). 

The oxygen isotope composition of a single grain from this population, indicate that this reservoir may be characterised by a different Δ17 O than the SNCs. If correct, the SNCs might not be representative of the bulk martian composition, but plausibly reflecting interaction with a heavy Δ17 O surface reservoir. Therefore, a main objective behind this study was to obtain high-precision oxygen isotope composition of 10 SNC meteorites to potentially detect Δ17 O heterogeneity. However, initial results show no isotopic variability, thus suggesting that the SNC source reservoir has not experienced interaction with surface reservoir, or that any heterogeneity has been erased.

Read the full scientific report, with kind permission from Siw Egdalen.

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

Virtual visit by Alice Stephant, Istituto di Astrofisica e Planetologia Spaziale (Italy) to TA2 Facility 21 – OU NanoSIMS 50L (UK).
Dates of visit: 24 March – 25 August 2022

One of the major unresolved questions in the field of cosmochemistry is to understand the source(s) and timing of volatile delivery in the inner Solar System. The goal of this project was to examine primitive achondrites which volatile inventory has not yet been investigated, in order to determine what portion of these volatiles was incorporated in the early stages of the Solar System history, relative to late-veneer delivery. In this regard, primitive achondrite acapulcoites and lodranites were selected as they sample a common parent body, hence allowing to also investigate the effect of various degrees of planetary differentiation on volatile abundances and isotopic compositions. 

Using the NanoSIMS 50L at the Open University, we analysed chlorine and water content, as well as their associated isotopic composition in phosphates from three acapulcoites and two lodranites. Our results suggest that the acapulcoite-lodranite parent body incorporated a similar source of volatiles than ordinary chondrites, which chemical composition is similar to the chondritic precursor of acapulcoites and lodranites, arguing for a common reservoir of both Cl and H in the inner Solar System.

Read the full scientific report, with kind permission from Alice Stephant.

20-EPN2-052: Water in silica-bearing iron meteorites – implications for early Solar System dichotomy

Visit by Ana Černok, Freie Universität Berlin (Germany)/University of Trieste (Italy) to TA2 Facility 21 – OU NanoSIMS 50L (UK).
Dates of visit: 14-21 November 2022 and virtual visit from 28 November – 20 December 2022

Understanding the volatile inventory of the earliest Solar System is inseparable from understanding which sources contributed to the volatiles of the oldest and relatively dry non-carbonaceous (NC) objects formed in the inner Solar System, and if they were different from wet carbonaceous (CC) materials, formed in the outer Solar System.

Two questions remain largely unanswered in this respect: (i) What are the abundances and isotopic composition of volatiles in the oldest NC objects and (ii) What were their sources? These questions can be answered by investigating some of the oldest objects in the Solar System, namely, the NC iron meteorites.

This Europlanet visit to the NanoSIMS facility was focused on trying to determine the content and isotopic composition of H or H₂O inside minerals within iron meteorites. The iron meteorites are some of the oldest formed materials in the Solar System and hold key evidence if there has been any water available when they formed, and if there was: where did this water originate from?

Here we focused on understanding water abundance and its isotopic composition in some of the oldest NC silica bearing iron meteorites (IVA type): Muonionalusta, Gibeon and Steinbach. Other investigated irons did not contain any silica. The lowest water content was measured in Gibeon (< 10 ppm) and Muonionlusta (15–20 ppm), while minerals in Steinbach contained significantly more water (40–120 ppm). The δD values for Gibeon show a large range and greater uncertainties, due to low measured water contents. The δD values in Muonionalusta and Steinbach cluster between ~0–300 ‰. In fact, silica phases in both minerals cluster between ~0–200 ‰, while low-water cpx in Steinbach shows the highest δD values (200–300 ‰). The difference in δD values between mineral phases in Steinbach likely reflects the difference in their crystallisation history, where opx may have lost H resulting in increased D/H ratio (higher δD) due to degassing. Overall, the source of water in these NC irons is very similar to that of the Earth and the chondrites, while low-D reservoirs have not been detected.

Read the full scientific report, with kind permission from Ana Černok.

20-EPN2-093: Linear gullies on Mars

Visit by Lonneke Roelofs, Utrecht University (Netherlands) to TA2.20 Open University Mars Chamber (UK).
Dates of visit: 21 November – 16 December 2022

Report Summary: A vast range of different gully morphologies occurs on Mars: from the classical gullies, which resemble gullies on Earth, to linear gullies that do not have an Earth counterpart and are found on Martian dunes. Previous experiments have shown that the sublimation of CO₂ ice can fluidise and transport sediment in the classical gullies on Mars. However, the linear gullies are hypothesised to form by a different, although related CO₂-driven mechanism. For linear dune gullies, it is hypothesised that they form by a block of CO₂-ice sliding down the dune. This process has, however, never been observed in real life.

With our visit to the Mars chamber at the Open University, we aimed at deciphering the triggering and forming mechanisms of linear dune gullies on Mars. We identified the possible triggering mechanisms based on hypotheses presented in the literature. The identified mechanisms are; 1) the breaking off and sliding down of CO₂-ice blocks, and 2) wind-blown sand being deposited on CO₂ frost. We systematically tested these mechanisms in the Mars Chamber at the Open University by means of experiments. For all identified triggering mechanisms a parameter space was used to test the influence of e.g. CO₂-ice block size, surface slope and grain size.

With our experiments, we show that CO₂-ice blocks slide downslope and create small narrow gullies when dumped on top of fluvial sand, with a large grain-size distribution. However, when dumped on a finer aeolian sand under Martian atmosphere, they do not slide downslope but they dig themselves into the sand, slowly digging a gully downslope by vigorous sublimation and sediment mobilisation. We also show that when a small amount of warm sand is dumped on top of a CO₂-frosted the sand is mobilised by CO₂ sublimation, but that this process does not create the typical linear gullies we see on Mars.

20-EPN-066: Experimental investigation of CO2 frost condensation and sublimation through sediments in Martian conditions – implications for martian gullies and jets

Visit by Camila Cesar, University of Bern (Switzerland) to TA2.20 Open University Mars Chamber (UK).
Dates of visit: 24 October – 18 November 2022

Report Summary: Our experimental campaign aimed to understand sediment transport driven by CO2 ice sublimation condensed inside a porous regolith. To quantify the erosion of sediment associated
with the sublimation of CO₂ frost in the subsurface of a ~30° slope, we tested various compositions (MGS-1, sand, sand-dust mixtures). While some sediment showed little to no activity over several attempts (sand), others showed significant slope activity (sand + >=10% MGS clay).

Read the full scientific report, with kind permission from Camila Cesar.

20-EPN2-106: The effect of ice substrate to formation of mud flows in a low-pressure environment: insights for Martian sedimentary volcanism

Visit by Ondrej Kryza, Institute of Geophysics of the Czech Academy of Sciences (Czech Republic) to TA2.20 Open University Mars Chamber (UK).
Dates of visit: 21 June – 12 July 2022

Report Summary: This project was designed to extend previous research of mud behaviour in the low-pressure conditions – with implications for potential sedimentary volcanism on Mars. The main objective was to test the effect of ice (or combined ice-sand) substrate to flow abilities and finite morphology of mudflows. As secondary objectives, testing of various inclinations of the surface, investigation of potential thermal erosion and extended study of another type of surfaces were implemented. 

In the first part of the project, nine successful experiments, with pure and variously inclined (2-10°) ice surface, confirmed a different style of mud propagation than in case of the frozen sandy surface. The major observations are: 1) dominant and prevailing boiling of mud mixture during the propagation over deeply frozen ice surface (confirms significance of latent heat related to melting/recrystallization), 2) explosive potential of ice when in contact with the boiling mud (fracturing, contraction-dilatation). The effect of slope in tested range has no significant impact on these observations.  

The second type of experiments tested combined ice-sand upper lid. Here, transition between boiling and freezing of mudflows was faster and finite morphology was more similar to lava-like flows which were described by Brož et al. (2020a). 

In both cases, the thermal erosion was not confirmed. Moreover, during sectioning and investigation of the finite mudflow shapes and their base, the developed bumps, irregularities or even increased porosity of ice lid were discovered. This might refer to more complex thermal exchange between ice and mud with a sequential melting and re-freezing. 

22-EPN3-032: Soil carbonate clumped isotope-based reconstruction of temperature evolution over the Mid-Pleistocene Transition and the Late Pleistocene

Visit by Ramona Schneider, Uppsala University (Sweden), to TA2 Facility 17 – Isotoptech Stable/Clumped Isotopes Laboratory (Hungary).
Dates of visit: 20 February – 03 March 2023.

Report Summary: This study describes the use of carbonate clumped isotope thermometry as a method of reconstructing paleotemperatures from soil carbonate concretions. The method is based on the tendency of rare, heavy isotopes of carbon and oxygen to clump together in a single CO₂ molecule, which is temperature-dependent. 

The analysis was performed on 12 samples that forme under a Mediterranean climate regime in Tajikistan to investigate the suitability of these samples for clumped isotope thermometry. The reconstructed temperatures of the Tajik Holocene soil carbonate nodules from three different locations show promising results, indicating that the Δ₄₇ clumped isotope method provides reliable results for this sample type.

The obtained temperature values showed that these carbonates record temperatures that are biased towards summer temperatures. This is likely due to their formation during the summer when temperatures are highest and precipitation ceases after the maximum annual rainfall period. Even the results from older soil carbonates that formed under glacial and interglacial stages dating several glacial cycles back (MIS 11-12 and MIS 21) are well constrained, but a clear difference in formation temperature between glacial and interglacial stages could not be observed. This result can possibly be explained by formation processes of the soil carbonates, but more chronological and temperature data is required to further test this assumption and to investigate which exact period of the geological history is represented by the reconstructed temperatures. Despite these uncertainties, these initial results are very promising and highlight the potential of this method for paleotemperature reconstruction in Central Asia.

20-EPN2-124: High resolution 14C dating of last glacial loess deposits on Jersey, Channel Islands

Visit by Yunus Baykal, Uppsala University (Sweden), to TA2 Facility 16 – Carbon-14 Dating AMS Laboratory (Hungary).
Dates of visit: 04 – 09 December 2022.

Report Summary: High latitude, ice marginal regions are efficient sources for atmospheric dust. Dust plays a fundamental role in the Earth’s climate system both driving and responding to climate change. Last glacial loess deposits in NW Europe potentially record past dust emissions from regions marginal to the former Eurasian Ice Sheet. However, uncertainties over the age of these deposits essentially limit their potential in reconstructing past dust activity. This project aims to build a detailed chronology of last glacial dust deposition in NW Europe through combined luminescence and ¹⁴C dating of loess on Jersey (Channel Islands).

During the Europlanet-funded 6-day research visit to the ¹⁴C accelerator mass spectrometry laboratory in Debrecen, Hungary radiocarbon dating of fossil gastropods embedded in the loess was conducted. Preliminary results are in good agreement with the existing, yet unpublished luminescence chronology. However, some ages may underestimate the depositional age due contamination from post depositional carbonate leaching. Nevertheless, the ¹⁴C ages from gastropod shells serve as valuable cross check of the OSL data and help to build a more robust age model for the loess section based on two independent dating methods.

21-EPN-FT1-023: Diagnostics of electron collisions with small organic molecules present in the atmospheres of small bodies and planets

Visit by Bartosz Michalczuk, Siedlce University (Poland), to TA2 Facility 13 – Electron Induced Fluorescence Laboratory (Slovakia).
Dates of visit: 21 – 30 November 2022

Report Summary:

The main objective of the project was to study electron impact processes of small organic compounds, using acetone as the first target.

• Record and analyse emission spectra of acetone induced by electron impact at several different energies in the range 10 – 100 eV.
• Determine emission cross sections corresponding to selected most intensive transitions in range of impact energies (from the thresholds of selected process to 100 eV).
• Identify neutral products of electron impact fragmentation of acetone.
• Determine reaction kinetics parameters such as threshold energies for selected electron impact excitation reactions of acetone.

During the first half of the visit, we measured electron-impact spectra of acetone at multiple electron energies and generated partial spectral electron energy map which provides the spectral information at various electron energies and thus the efficiency curves (relative emission cross-section curves).
During the second half of the visit, the measured data was partially analysed. The emission band in the range of 415 – 445 nm corresponds to the radiation of CH (A²Δ–X²Π) (ν,ν) fragment. Less intensive radiation of CH (B²Σ−–X²Π) (0,0) fragment was identified within 386 – 402 nm. Several emission lines of hydrogen’s Balmer series Hγ – Hη were detected throughout the spectrum as well. Individual rotational transitions from P, Q, R branches of both CH fragments were identified according to LIFBASE 2.1.1 spectroscopy tool, which is software to chart the spectroscopy of diatomic molecules. The rotational temperature of the LIFBASE spectrum was set to ~ 5000 K.

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

20-EPN2-070: Formation of Glycine and Alanine Upon Ion Irradiation of Space-Relevant Ices

Visit by Alejandra Traspas Muina, Queen Mary University of London (UK), to TA2.11 Atomki Ice Chamber for Astrophysics / Astrochemistry (ICA) (Hungary).
Dates of visit: 20 March – 2 April 2023

Report Summary: The experiments initially proposed aimed to investigate the formation and chemical evolution of both glycine and alanine under space relevant conditions. Following a systematic approach, the TA was divided into three projects carried out by a multidisciplinary group of scientist (chemists, biologists, astrophysicists and engineers): looking at (i) experimental insights into the microphysics of molecule destruction and sputtering of CO₂ exposed to cosmic rays analogues; (ii) the formation of methyl formate and its isomers (glycolaldehyde and acetic acid) through the systematic irradiation of H₂ CO:CO, H₂ CO:CH₄ , and H₂ CO:CH₃ OH ice mixtures with 1 MeV and 200 keV H⁺ ; (iii) and 1 MeV H⁺ irradiation of pure Glycine and Glycine:CH₄ interstellar relevant ice mixtures, exploring the survivability and stability of this amino acid in astrophysical relevant environments.

The three projects were designed with incremental molecular complexity to investigate the chemistry of many precursors of simple amino acids. Moreover, the sub-projects were designed to be connected to other awarded TAs either at ICA or AQUILA (PIs: Ivlev, Ioppolo, and Hopkinson) in a synergic manner. For instance, the work of H₂ CO completes the systematic study on methyl formate and its isomers, started at this Europlanet facility 2 years ago, trying to improve the understanding of the standing dichotomy on the formation of glycolaldehyde, methyl formate, and acetic acid. All these species are detected in space in star-forming regions and are considered prebiotic molecules.

Full scientific report published by kind permission of Alejandra Traspas Muina