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
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
20-EPN-049: The Irradiation of Oxygen-Bearing Ices on Top of Pure Elemental Sulphur Layers (former title: Millimetre-Wave Polarimetry of Space Relevant Ices Exposed to Energetic Ions)
Virtual visit by Olivier Auriacombe, Chalmers University of Technology (Sweden), to TA2.11 Atomki Ice Chamber for Astrophysics / Astrochemistry (ICA) (Hungary).
Dates of visit: 20 June – 4 September 2022
Report Summary: The chemistry of sulphur in icy extra-terrestrial settings such as the dense interstellar medium and the outer Solar System remains poorly constrained. In particular, the chemical routes towards the formation of SO2 ice (and other volatile sulphur-bearing species) is not completely understood, despite the detection of this species in interstellar icy grain mantles, on the surface of Europa, and on comets. We have therefore explored the possibility of forming SO2 ice as a result of the irradiation of oxygen-bearing ices (including O2, CO, CO2, H2O, and CH3OH) deposited on top of pure elemental sulphur layers, both of which are known to exist in the dense interstellar medium and the outer Solar System where radiation chemistry may be engendered by galactic cosmic rays or the solar wind.
Our results demonstrate that SO2 may indeed be produced after the 1 MeV He+ ion irradiation of O2 and CO2 ices deposited on top of elemental sulphur, but not as a result of similar irradiations conducted using CO, H2O, or CH3OH ices. Other volatile radiation product species incorporating sulphur, such as CS2, OCS, and H2SO4, were also detected in different experiments. Our work should therefore contribute to a better understanding of solid-phase sulphur astrochemistry and the role of elemental sulphur in the formation of volatile sulphur-bearing species in icy extra-terrestrial settings.
20-EPN2-045: Irradiation Effects of Energetic H+ and S+ Ion Implantation in Salts and Minerals Relevant to the Surface of Europa
Virtual visit by Duncan Mifsud, University of Kent (UK) to TA2.11 Atomki Ice Chamber for Astrophysics / Astrochemistry (ICA) (Hungary).
Dates of visit: 21-29 November 2022 and 18-20 January 2023
Report Summary: The surface of Europa is host to a rich radiation environment, in which ions from the giant Jovian magnetosphere drive physico-chemical transformations of surface ices and minerals. Although a number of previous studies have looked into the irradiation of surface ice analogues in order to better constrain the chemistry occurring on Europa, considerably fewer studies have investigated the radiation chemistry of plausible mineral analogues.
Therefore, in this study, we have irradiated four mineral species (halite, fayalite, epsomite, and berthierine) using 1 MeV H+ and 1 MeV S+ ions to better understand the dissociation pathways of these minerals and the associated radiolysis products. Our preliminary results have shown that irradiation brings about significant changes in the appearances of the minerals that signify alterations in the structures and chemical compositions. Further infrared, visible, and ultraviolet spectroscopic analyses of retained mineral samples (both irradiated and pristine) are planned for the near future.
20-EPN-025: Radioresistance of aromatic complex organic molecules (nucleobases)
Virtual visit by Alicja Domaracka and Anna Bychkova, CIMAP-CNRS (France) to TA2.11 Atomki Ice Chamber for Astrophysics / Astrochemistry (ICA) (Hungary).
Dates of visit: 17-28 January 2022
Report Summary: Over the last decades it became clear that we live in a “molecular universe”. Carbon forms the basis of the majority of the molecular species that so far have been identified in space. Although small carbon-based molecules, like CO and CO2, are some of the most abundant molecules in space, only a small fraction of the carbon is expected to be locked up in such species. It was proposed that a large portion of the interstellar carbon, up to 20%, is built in polycyclic aromatic hydrocarbons (PAHs) and fullerenes. Several laboratory studies were carried out to investigate the effects of vacuum ultraviolet photolysis on PAH:H2O ices. However, data about interaction energetic ions with PAH ices are very scare.
We therefore studied the radiolysis of the pure pyrene ice and mixed pyrene- water ices at different concentrations at 20 K with 200 keV and 2 MeV H+ and 2 MeV C2+ beams at Atomki. The preliminary analysis of water-pyrene ices irradiated 200 keV H+ (with pyrene concentration from about 5 to 100% of pyrene) indicates that pyrene is more radio-resistant at high concentrations. The results are preliminary and analysis is ongoing.
20-EPN2-017: Resolving critical uncertainties in the impact of geomagnetism on in situ cosmogenic nuclide production via long-term calibration
Visit by Gordon Bromley, University of Galway (Ireland), to TA2.9 Ion Probe Facility (IPF), CRPG (France).
Dates of visit: 17 – 21 October 2022
Report Summary: Cosmogenic nuclide (CN) surface-exposure dating (SED) has revolutionised geomorphology in recent years, enabling the direct determination of both the rate and age of Earth surface-processes. However, SED relies on strict quantification of CN production rates (PRs) for both the time-period and location in question; for many sites and times periods such data is rare. As a result, calculated exposure ages may vary significantly depending upon the assumptions and model schemes employed in calculations. The impact of geomagnetic field variability on nuclide production is particularly uncertain.
The goal of this project is to test explicitly the methods used to calculate exposure ages, and to assess their viability over space and time. To do this, we measured cosmogenic helium-3 within a series of Peruvian lavas of varying age at the Stable Rare Gas and Radiogenic Isotope Facility, CRPG (France). Paired with later Ar/Ar age determination, we are using these new cosmogenic helium data to produce a series of discrete CN production rates from a single geographic region, and so will assess the variability of nuclide production through time. Our preliminary results indicate the research plan is viable: cosmogenic helium data from single lava flows are internally consistent. Lavas analysed range in age from ~1.6 ka to ~175 ka, and so provide a dataset that spans a period sufficient to assess changes in PR and the potential impact of magnetic field variability on CN PRs. We anticipate sharing final project results within a peer-reviewed, open-access publication within the calendar year.
Read the full scientific report, with kind permission from Gordon Bromley.
20-EPN2-053: Noble gas (3He) analyses of iridium poor marine sediments to understand the astronomic process responsible for the late Eocene meteor shower
Visit by Jörg Fritz, ZERIN (Germany), to TA2.9 Ion Probe Facility (IPF), CRPG (France).
Dates of visit: 06 – 15 April 2022
Report Summary: The project aims to understand the astronomical processes leading to the late Eocene shower of extraterrestrial (ET) material onto Earth. The 3He-carrier phases responsible for the ~ 2 million years enduring 3He anomaly will be characterised geochemically by producing a combined 3He and Ir dataset.
Here, 23 samples of marine micro-fossil ooze form the ODP 689B core, Maud Rise, Southern Ocean were measured at the CRPG Nancy noble gas laboratory. These samples cover the Eocene Oligocene transition (38 to 33 Ma) and these new data document the amplitude and duration of the 3HeET anomaly and confirms that the late Eocene 3He anomaly reported from the Massignano outcrop (Italy) is a global phenomenon. The here-investigated 689B micro-fossil ooze is exceptional because its low terrigenous mineral content and low iridium concentration of 5-15 ppt Ir. These Ir values are close to the expected ET contribution of 12 ppt Ir, as calculated using the current global/annual ET flux and the sedimentation rate and dry density of the 689B deposits.
The 3He data set acquired during the TA visit combined with literature data on Ir concentrations show that the flux of 3He rich ET particles increase by 4 times whereas the Ir concentrations in 689B remain at background values. New Ir data with low detection limits will further constrain the relation between ET 3He and total Ir during the late Eocene shower. ET 3He does not correlate with Ir indicating that the late Eocene 3He anomaly was caused by 3He-rich and Ir poor dust particles. The study illuminates the potential of marine micro-fossil ooze for planetary science.
21-EPN-FT1-019: Isotopic composition of single detrital carbonate grains in the source-to-sink study of the Bengal Fan record
Visit by Mara Limonta, University of Milano-Bicocca (Italy), to TA2.9 Ion Probe Facility (IPF), CRPG (France).
Dates of visit: 25 July – 05 August 2022
The Bengal Fan forms the largest deep-sea turbidite system on Earth and hosts a unique sedimentary record of the evolution of the Himalayan orogenic belt.
This study aims to develop a new protocol to analyse single-grain isotopic signatures of detrital carbonates with primary application in source-to-sink studies and to foster the application of oxygen and carbon isotopes on single detrital grains of carbonates as a provenance tracer. δ18O and δ13C fingerprint of single detrital carbonate grains in Bengal Fan turbidites (IODP Expedition 354) will allow to detect and quantify the signature of different carbonate rocks from the Tethys Himalaya and High Himalaya and to better reconstruct the evolution of erosion processes in the Himalayan belt. This work will allow also testing the feasibility of the new single-grain approach. δ18O and δ13C fingerprint of detrital carbonate grains of selected Bengal Fan turbidites could not be measured due to their fine sand to silt grain-size.
We establish the grain-size feasibility limit at 200 microns in grain diameter. Otherwise, oxygen and carbon isotopic signature of single carbonate grains from Marsyandi and Kali Gandaki modern sand-sized river sediments were analysed to characterize isotopic fingerprint of carbonatic source rocks of Tethys Himalaya unit exposed along their drainage basin. Detrital carbonates of Marsyandi and Kali Gandaki rivers show similar low δ18O values, indicating depletion by metamorphic reactions. δ13C values range from +2‰ and -2‰ and mostly positive δ13C values characterise Kali Gandaki, whereas mostly negative δ13C values characterise Marsyandi carbonate grains.
20-EPN2-072: Dynamics of the early inner solar system inferred from combined 26 Al-26 Mg and Cr–Ti–O isotope systematics of non-carbonaceous chondrules
Visit by Christian Jansen, WWU Münster (Germany) to TA2.9 Ion Probe Facility (IPF), CRPG (France).
Dates of visit: 03-12 August 2022
Report Summary: The advent of non-traditional isotopic systems (e.g., Ti, Cr, Mo) revealed that chondrites—the most primitive witnesses of the early solar system—display a fundamental isotopic dichotomy, with carbonaceous chondrites (CCs) showing large nucleosynthetic anomalies relative to terrestrial standards that are not observed in non-carbonaceous chondrites (NCs). NC and CC reservoirs may thus represent the primordial inner and outer parts of the solar system, respectively.
The scientific goal of this project is to combine several isotopic systems (O, Ti, Cr) for deciphering the conditions and chronology of chondrule formation in the NC reservoir. A key parameter of this approach is to also have access to the formation ages of these chondrules. This requires in situ measurements with a secondary ion mass spectrometer for determining the 26Al ages of chondrule crystallisation.
To do so, 16 chondrules were separated from the minimally altered ordinary chondrite NWA 5206. They were split into two pieces for determining their (i) Cr and Ti isotopic compositions (bulk measurements) and (ii) O isotopic compositions and 26Al ages. These chondrules show no 54Cr or 50Ti excesses and classical oxygen isotopic composition (with ∆17 O ranging from -1 to + 1 ‰). 26Al ages are coherent with previous estimates showing that NC chondrules formed over several million years during the evolution of the inner disk.
20-EPN2-102: A new source of water from Mars
Visit by Tim Tomkinson, University of Bristol (UK) to TA2.9 Ion Probe Facility (IPF), CRPG (France).
Dates of visit: 05-09 December 2022
Report Summary: Here we have searched for a source of D-enriched Martian groundwater previously discovered in the Martian meteorite Lafayette (up to δD 4725‰) within olivine defects below the secondary mineral phyllosilicate. These groundwaters which are known flowed through this sample 670 Ma were sourced from the Martian atmosphere, or had equilibrated with it, and diffused up to ~1.5 µm into the olivine via shock-formed defects in vein walls. In this project we want to determine a calibration line to resolve the water content on the Martian olivines and find a potential location of new water within the defects.
Two 1 inch indium mounts were prepared with olivine plus glass standards and paired Martian nakhlite samples (Yamato 593, 802, 749, Lafayette and Nakhla) to confirm this source of Martian ground water. Work was conducted with Dr Johan Villeneuve and Dr Laurette Piani on the Cameca IMS 1270 E7 ion probe at CRPG, Nancy. The new obtained/formed standards provided calibration to measurements of water contents (H2O%) within the Martian olivines and when combined with standards from CRPG δD values were roughly constrained. Owing to the unique surfaces of each Martian altered olivine it was impossible to confirm pre analyses if defects hosting water would be present in the outer olivine surfaces. Results show a location where an enriched δD was present, further investigations such as Transmission Electron Microscopy (TEM) are required to confirm this.
20-EPN2-067: Hydrogen isotope compositions of matrices in unequilibrated ordinary chondrites
Visit by Helen Grant, University of Manchester (UK) to TA2.9 Ion Probe Facility (IPF), CRPG (France).
Dates of visit: 10-21 October 2022
Report Summary: One way to study the origin of water and other volatiles which accreted onto rocky planets such as Earth during the formation of the Solar System is to study meteorites that fall from asteroids and other planetary bodies. Hydrogen isotope ratios within meteorites can be used as a tracer for the source of a body’s water, and to an extent spatial and temporal information about the formation of parent bodies.
Previously, we measured the D/H ratios of bulk powders of a wide range of unequilibrated ordinary chondrites (UOCs), and found wide variations which did not fit into current H-distribution models. Using SIMS, we measured the H, D, C, and Si contents of the fine-grained matrix of 13 of these previously studied UOCs (only falls) ranging from types 3.00 – 3.9. Preliminary results confirm the wide previously observed spread of D/H ratios between samples, including high elevations in a handful of UOCs. C/H ratios will be used to determine the D contribution within samples specific to water, however initial observations confirm contributions from both hydrated and organic components. The results from this visit will be combined with other in-situ studies carried out at the home institution to determine exactly what phases are hosting this highly D-rich material, and how these chondrites affect models of water transport in the early Solar System.
Read the full scientific report, with kind permision from Helen Grant.
21-EPN-FT1-006: Melting phase relations of subduction zone minerals and their nitrogen budget
Visit by Caterina Melai, University of Bayreuth (Germany) to TA2.9 Ion Probe Facility (IPF), CRPG (France).
Dates of visit: 29 August – 02 September 2022
Report Summary: In this study the phase relations of hydrous aluminosilicate minerals (e.g. montmorillonite, phlogopite, phengite and serpentinite) that are present in sedimentary layers or form during early prograde metamorphism of the oceanic lithosphere are investigated at sub-arc conditions. The investigated minerals are potential hosts for nitrogen at different P-T conditions along the subducting slab, depending on their phase stabilities and the N partitioning upon partial melting of these phases. In the present analytical session, several minerals in equilibrium with melt (quenched glass) have been analysed by means of SIMS.
The measurements in this report were performed using the CAMECA 1280 HR2 Ion Probe at CRPG, France. All the experimental capsules planned for the session were analysed and additional secondary standards were investigated.
The experimental samples showed consistent and reproducible N content on the different measured spots both on the mineral and the melt phase. More challenging was the measurements of the standards that confirmed the existing concern on the possible matrix effect during SIMS measurements of mineral phases. The different behaviour of the light elements analysed in a glass or crystalline matrix appears to have a strong effect on the measured nitrogen ion yield.
The work performed during this analytical session at the SIMS, allowed the acquisition of the N data for the calculation of the partition coefficients between mineral and melt while providing additional evidence for the need of further investigation of the matrix effect for this technique.
Read the full scientific report, with kind permision from Caterina Melai.
20-EPN-031: Investigating volatiles in the early Solar System through analysis of halogens in chondrules
Visit by Edward Baker, University of Manchester (UK) to TA2.9 Ion Probe Facility (IPF), CRPG (France).
Dates of visit: 13-17 December 2021
Report Summary: We have measured the concentration of halogens in the glasses of chondrules from enstatite chondrites. There is a clear correlation between Chlorine and Bromine abundances, but no clear relationship between Cl or Br and F. Iodine was not measured. In the main S is well correlated with Cl: this trend may have been modified by unintended analysis of micron scale blebs on sulphide. Halogen profiles have been taken across a number of suitable target chondrules, for diffusion modelling, which will be presented and published in due course. The array of data for F/Cl is sub-chondritic while the Br/Cl array is super-chondritic.
Evaporation and condensation may play important roles in controlling halogen behaviour, along with partitioning between other significant reservoirs in chondrites because fluorine is likely to be compatible in a number of silicate minerals. More will be known after diffusion modelling and after the experimental partition coefficients have been determined.
Read the full scientific report, with kind permision from Edward Baker and Rhian Jones.
21-EPN-FT1-005: Reading the sedimentary archive of discontinuity surfaces
Visit by Simon Andrieu, Aarhus University (Denmark) to TA2.9 Ion Probe Facility (IPF), CRPG (France).
Dates of visit: 18-22 October 2021
Report Summary: Discontinuity surfaces, associated with seafloor cementation, are hence of primordial importance for fully apprehending the geological record, yet they have received far less attention than the sedimentary rocks surrounding them. Fundamental problems that are still not sufficiently understood concern the lateral change of discontinuities. In this project, we tackle this issue by studying the lateral variation of five distinct discontinuity horizons present in the Middle Jurassic of the High Atlas (Morocco), where outstanding exposures permit to track these surfaces over tens of kilometres. Hence, the purpose of this work is to characterise at a high-resolution the large-scale variation of petrographic and geochemical (C, O and Sr-isotopes) properties of discontinuities (matrix and cement phases) along dip and strike of a Jurassic moderately deepening ramp. δ18O (176 values) and δ13C (105 values) signatures were obtained on twenty-one cements and grain types, including 14 different early calcite cements and fabrics corresponding to dogtooth cements (7), turbid synaxial cements (1) and micritic/microsparitic fabrics (6).
Data confirm that dogtooth cements can precipitate in marine phreatic, meteoric phreatic and shallow burial environments. The highly negative δ18O values of micritic fabrics and turbid synaxial cements, which form in seawater, indicate that they transformed during subsequent diagenesis (i.e during meteoric water circulation or shallow burial). It indicates that they precipitate initially with an unstable mineralogy (aragonite or high-magnesium calcite). δ18O and δ13C data on early cements suggest that a same discontinuity can change laterally from a subaerial exposure surface to a marine surface.
Read the full scientific report, with kind permision from Simon Andrieu.
21-EPN-FT1-003: Spectral signatures of amino acid and polypeptide embedded in water ices – Implications for biosignature identification on icy moons
Visit by Surendra Vikram Singh and Bhalamurugan Sivaraman, Physical Research Laboratory (India), to TA2.8 CSS (Cold Surfaces Spectroscopy) at IPAG (France).
Dates of visit: 23 May – 08 June 2022
Report Summary: The objective of the experiments was to obtain a spectral library of biomolecules such as amino acids in water ice in context of icy bodies of solar system. We performed a series of measurements obtaining reflectance spectra of glycine –water ice mixtures in the VIS-NIR range (0.4-4.2 μm) at the temperature range of 110-250 K and at three different concentrations, using Cold Surface Spectroscopy Facility (CSS) setup at IPAG. Glycine – water ice mixtures were studied in two different mixing modes (inter and intra mixing) to get the spectral variations due to dissolving amino acids into water. Reflectance spectra of pure glycine and pure water ice were also obtained for reference. Reflectance spectra for a shocked glycine sample (obtained from HISTA facility at PRL) was also studied to understand the effect of shock induced chemistry. These measurements will support to find the spectral signature of amino acids on icy bodies of solar system.
21-EPN-FT1-025: Ammonium salts reflectance spectra changing viewing geometry for distinguish them on the surface of icy planetary bodies
Visit by Maximiliano Fastelli and Matteo Bisolfati, University of Perugia (Italy), to TA2.8 CSS (Cold Surfaces Spectroscopy) at IPAG (France).
Dates of visit: 13-25 June 2022
Report Summary: During the Europlanet 2024 RI TA Fast Track call, reflectance VIS-NIR spectra were collected at the CSS facility (IPAG) in Grenoble, France. Different viewing geometries were chosen to collect BRDF spectral data of a selected group of ammonium minerals. BRDF were collected in the 1 – 4.8 μm range considering a set of 3 incidence angles (i) (i = 0°; 30°; 60°) and 8 emergence angles (e) between -70° and 70° at room temperature. The NH4+overtone and combination bands located at ~ 1.09, 1.32, 1.62, 2.04, 2.2 and 3.05 μm are experimentally investigated.
The bands position remains unchanged varying geometrical configuration. On the other hand bands area and depth shows the highest values for i = 0° and 30° and e below 40°. These band parameters at ± 70° emergence angles evidence a decrease in their values. A general trend of spectral red shift with phase angle is observed. The bidirectional reflectance spectroscopy of selected samples shows important variations with the observation geometry of the measurements. Furthermore, from these preliminary data analyses, can be observed how reflectance values and spectral slope are affected by geometry of measurements. The surfaces of the planetary bodies are irregular and rough, which is why the effect of the observation geometry must also be considered. The collected data set can be helpful in the context of future missions aimed to understand the nature of minerals on icy and small bodies. NH4+–bearing minerals identification has a strong impact on understand their thermal evolution and the construction of geophysical internal models.
20-EPN2-100: Spectroscopic Identification of Experimental Basalt Alteration Products Under Venus Conditions
Visit by Molly McCanta, University of Tennessee (USA), to TA2 Facility 5 – DLR Planetary Spectroscopy Laboratory (Germany).
Dates of visit: 14 – 20 October 2022
Report Summary: Experiments and thermodynamic modelling clearly show that sulfates are a common alteration product under the high temperature, CO2-SO2-rich conditions at the surface of Venus. The exact sulfates present depend on the original basalt composition, with anhydrite (CaSO4) and thernardite (Na2SO4) having been observed in the lab (Reid et al., 2023).
Alteration rates calculated from these experiments suggest that sulfate coatings may develop geologically fast and therefore alteration coatings may obscure the original protolith. Additionally, the spectral features of these high temperature sulfates are not well constrained. Although many critical sulfate minerals are stable to temperatures > 500C, previous analytical data has generally explored sulfate-temperature spectral relations to ~100C. The surface of Venus is significantly hotter at 470C. Thus is makes sense to investigate both the effects of variable thickness sulfate coatings and the spectral properties of sulfates under Venus surface conditions to gain a better understanding of their behaviour.
The next set of Venus missions will have observational capabilities in the thermal emission spectrum (range) and high T sulfate spectra are presented in another paper (Dyar ref); here we present data for the effects of high T on visible near-infrared (VNIR) sulfate spectra. In addition, we have conducted experiments to determine the effects of sulfate coating thickness on the underlying surface spectra. The data presented may help determine future mission capabilities to both recognise and analyse sulfate-bearing materials under high T conditions as well as constrain the original, unaltered surface composition.
20-EPN2-097: Venus-Temperature Emissivity Experiments on Pure Minerals
Visit by Melinda Darby Dyar, Mount Holyoke College (USA), to TA2 Facility 5 – DLR Planetary Spectroscopy Laboratory (Germany).
Dates of visit: 14 – 20 October 2022
This project supports a collaboration between the US and personnel at the Planetary Spectroscopy lab in DLR Berlin to understand the interrelationships among high temperature emissivity and high or ambient temperature reflectance measurements of rocks and minerals present on the surfaces of rocky bodies (planets, moons, and asteroids). We are investigating the extent to which spectral features in the near-IR wavelength region shift and change in intensity as a function of temperature and measurements type. These changes are easiest to understand when comparisons can be made for single mineral species.
With Europlanet support, we acquired hemispherical and bidirectional reflectance and emissivity spectra of planetary-analog minerals at the PSL at DLR Berlin. Minerals studied included pyroxene, feldspar, olivine, sulfates, and calcite minerals. Significant differences between hemispherical and biconical reflectance data were observed; as we write up the results, we will explore the underlying physical characteristics of each mineral group and relate them to the magnitude of those changes. We also observed significant differences between bidirectional reflectance spectra and emissivity results in preliminary results. This outcome suggests that laboratories seeking to make Venus-relevant measurements cannot draw conclusions about spectral intensities on the basis of bidirectional data.
20-EPN-027: Characterisation of the response of an Optical Particle Counter in a simulated Martian environment
Visit by Giuseppe Mongelluzzo and Gabriele Franzese, INAF (Italy), to TA2.4 Planetary Environment Facilities (PEF), AU (Denmark)
Dates of visit: 05-09 September 2022
Report summary: The characterisation of dust is paramount in the understanding of Martian climatology. Dust significantly influences Mars global climate, interacting with the incoming solar radiation, altering the atmospheric temperature budget. Local and global dust storms can cover the planet for weeks, influencing the correct functioning of scientific instruments on the surface (The Rover “Opportunity” is the most famous example). The dynamics of dust lifting is strictly related to the wind velocity field, so its characterisation would provide important information on the characteristics of Martian winds.
The proposing team has developed an Optical Particle Counter (OPC) aimed at providing direct measurements of grain concentration and size distribution on Mars, which would be the first ever accomplished outside of Earth. The instrument is able to detect dust grains in the 0.4-20 μm diameter range. Both the breadboard and the flight model versions of the instrument have been tested in Martian environment, showing good performances.
The trip to the Planetary Environment Facilities at the University of Aarhus has allowed the verification that the instrument is correctly able to sample dust grains in its upper sensible range (up to 20 µm in grain diameter) also in presence of winds up to 20 m/s. A sandbed with embedded dust has also been created inside the Martian wind tunnel, allowing the simulation of natural saltation conditions. The instrument has been able to retrieve dust grains in all simulated conditions, both for monodispersed calibrated dust samples and for polydisperse samples.
Read the full scientific report, with kind permission from Giuseppe Mongelluzzo.
20-EPN2-050: Turbulent suspensions of volcanic ash: an experimental simulation for eruptive and resuspension ash plumes
Visit by Jacopo Taddeucci and Elisabetta Del Bello, Istituto Nazionale di Geofisica e Vulcanologia, Rome (Italy), to TA2.4 Planetary Environment Facilities (PEF), AU (Denmark)
Dates of visit: 07-11 November 2022
Report summary: Ash Injection and settling experiments have been carried out using the environmentally controlled recirculating wind tunnel facility at Aarhus University, in order to understand the processes controlling deposition and segregation of ash from volcanic plumes at stratospheric altitudes.
Ash particles erupted from the Campi Flegrei volcano (Italy) and smaller than 63 micron were injected in the wind tunnel either from the upwind extremity in the presence of wind (1 m/s) or from the side in the absence of wind. The atmospheric pressure in the wind tunnel was systematically varied to simulate the corresponding elevation in the atmosphere from 10 to 50 km. The vertical and horizontal velocity of the particles was measured, as well as the plume opacity, proxy for particle concentration over time.
Settled particles were sampled at different times during the experiments and then analysed for their abundance and size distribution. Both the opacity measurements and the number of particles sampled over time display the decay of particle concentration over time in the suspended plume. The rate of decay is strongly dependent on the atmospheric elevation in a nonlinear way, with modest changes from 10 to 20 km elevation and much larger changes for higher elevations.
From these data we will retrieve experimentally the settling velocity of volcanic ash particles at a range of elevations that is of interest for both aviation and climate modelling implications.
Read the full scientific report, with kind permission from Jacopo Taddeucci.
20-EPN-054: Understanding large aeolian ripples on Mars through wind tunnel experiments
Visit by Simone Silvestro, INAF Osservatorio Astronomico di Capodimonte (Italy), and Hezi Yizhaq, Midreshet Ben-Gurion (Israel), to TA2.4 Planetary Environment Facilities (PEF), AU (Denmark)
Dates of visit: 04-08 April 2022
Report summary: In our experiments in the Planetary Environment Facility in Aarhus we obtained, for the first time, two superimposed ripple patterns on monodisperse sand beads in CO2 air.
The presence of two distinct sets of aeolian sand ripples in unimodal sand suggests two formational mechanisms. Morphological characteristics such as straight crests and regular spacing point toward an impact mechanism to be responsible for the formation of the smaller (cm-scale) ripples. Conversely, the higher sinuosity of the larger (decimeter) ripples suggest a different type instability (hydrodynamic) at work. We also detect an increase in sizes for the ripples with decreasing pressure which is currently under investigation.
Collectively, our work seem to confirm the hydrodynamic nature hypothesised for the large Martian ripples.
Read the full scientific report, with kind permission from Simone Silvestro.