20-EPN-004: Spectroscopy of Shock Processed Planetary Analogues Mimicking Impact Events on the Surface of Mercury

Visit by Arijit Roy and Wafikul Khan of the Physical Research Laboratory, Ahmedabad (India) to TA2 Facility 5 – DLR Planetary Spectroscopy Laboratory (Germany).
Dates of visit: 09-13 October 2023

Report Summary: The surface of the airless Solar System bodies has been modified both physically as well as chemically by the impacts induced shock processing. Planetary scientist uses multispectral
remote sensing technique to understand the surface chemistry of these airless planetary bodies. Different spectral ranges reveal distinct descriptions and characteristics of the observed planetary surface. Like, VIS-IR spectroscopy focused on a rocky planet provides insights into the distribution of iron (Fe) and titanium (Ti)-rich minerals, spanning both its igneous and sedimentary phases. In contrast, IR spectroscopy exposes the abundance of silicon-oxygen (Si-O) bonds, offering a glimpse into the bulk mineralogy of the surface. This leaded to the better understanding of the abundance of minerals and their distribution on the different planetary surfaces. Olivine is often observed on the surface of different Solar System objects such as Venus, Mercury, Our Moon, and Asteroid Vesta. In the case of Mercury
impacts allowed olivine to mixed with other abundant sulphides molecules and further processed by shock wave which induced a physico chemical changes leaded to a change in the spectral signature of the Mercury surface.

To address this issue we studied shock processing (5.6 M) of the olivine (dunite) with sulphur, where the mixture was processed at a temperature ~ 7300 K, for 2ms. The shock processed samples later analysed using PSL, DLR’s bi directional reflection spectroscopy set up from UV to FIR wavelength range.Results from this work will help the planetary science community to build a spectral library for the future planetary missions.

20-EPN-064: Impact induced polypeptide synthesis on low-temperature astrochemical ices containing amino acids

Visit by Ragav Ramanchandran and Jaya Krishna Mekaof the Physical Research Laboratory, Ahmedabad, (India), to TA2.7 Light Gas Gun Laboratory, University of Kent (UK)
Dates of visit: 25 June – 10 July 2023

Report summary: Impacts are the most common events across the solar system, shaping the evolution of planetary bodies,including icy satellites, such as Jupiter’s moon Europa, which are prime targets for future space missions finding signatures of life. Impacting bodies are known to deliver important organics, such as amino acids, to the planetary surface and sub-surface. Apart from this, high pressure and temperature created during impacts can provide pathways for chemical reactions leading to the formation of more complex molecules from simple precursors. Thus impacts have significant consequences for the potential habitability and synthesis of organic compounds.

We performed a series of experiments at the light gas gun facility of the University of Kent, simulating the impact on targets containing amino acids embedded in water ice. A stainless steel bolide of size 1.5 mm was used as a projectile and fired at a velocity of ~ 5 km s^-1. After impact, the ejecta ice materials were collected in a specially designed chamber, and materials were also collected from crates and theirsurroundings that were formed after impact. The collected materials will be analyzed using different techniques for the identification of synthesized products after impact. Previous studies suggested that building blocks of life, such as amino acids, can be synthesized by impact-induced processes. However, it is unknown how the formation of macromolecular architectures from the combination of simple building blocks would have happened. Our objective with these experiments will be to explore the formation of such macromolecules through impact events and explore potential pathways toward life.  

20-EPN-061: CO₂ Ice Crystals Formation Under Conditions in the Martian Polar Regions: Influence of Substrate Properties and Temperature Gradient

Visit by Ganna Portyankina, DLR (Germany), to TA2.4 Planetary Environment Facilities (PEF), AU (Denmark)
Dates of visit: 30 April – 01 October 2023 (two visits)

Report summary: The main goal of most recent tests conducted at the Planetary Environment Facilities at Aarhus University was to condense CO₂ from the chamber’s atmosphere under Martian conditions onto a specially designed set of different surface materials (martian regolith simulant, glass beads of various sizes, dust). We investigated ranges of temperatures and pressures and observed the texture of the created CO₂ ice. Our goal was to determine if CO₂ deposits over regolith/glass beads/dust differently compared to brushed aluminium. We have observed that various properties of substrate did not considerably alter the deposition morphologies of CO₂ observed in our previous work. Most importantly, we find that under conditions usual for Martian polar areas in fall and winter, CO₂ ice always deposits as a translucent slab.  Under deviating conditions, i.e. colder temperatures and lower pressures, CO₂crystals assume different shapes including opaque slab and highly porous multi-crystalline. Such CO₂crystalline morphologies require further investigations, because of their relevance to icy satellite surfaces as well as CO₂ cloud formation.

Read the full scientific report, with kind permission from Ganna Portyankina.

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-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.

20-EPN-030: Identification of Metabolic Activity in Millennial Old Cave Ice

Visit by Aurel Persoiu of the Emil Racovita Institute of Speleology (Romania) to TA2 Facility 17 – Stable/Clumped Isotopes Laboratory (Hungary).
Dates of visit: 15-29 November 2023

Report Summary: Scarisoara Ice Cave (Apuseni Mts., Romania) hosts a more than 10,000 years old ice block. Previous studies have shown that the ice hosts a varied microbial and fungal ecosystem, with more than 50% of taxa being culturable (i.e., alive). The main question of this project was whether the oxygen gas was consumed in the ice by the metabolic activity of microbes (and/or fungi), so we aimed to determine the Ar/O2 ratio in the gas extracted from the ice.

Two duplicate ice samples were analysed. One of them was deposited during the warm Medieval Warm Period, roughly between AD 800 and 1200 (labelled MWP), while the other accumulated during the subsequent cold Little Ice Age, between AD 1200 and 1850 (labelled as LIA). The Ar/Kr and Ar/Xe ratios indicate the ice was deposited as ponding water was slowly freezing. No entrapped air bubbles were present in the ice. This data fits to modern observations, since the top of the ice are covered by liquid water during summertime, which subsequently freezes in winter. As Ar/O2 ratios show oxygen depletion cannot be detected in the ice. The δ¹³C of CO₂ in the air equilibrated water samples compares to dissolved atmospheric CO₂, while δ¹³C in the ice samples represents depleted CO₂ from the root zone of vegetation growing above the cave. δ¹⁸O of O₂ is similar to that of atmospheric oxygen. As a conclusion, we cannot confirm that oxygen depletion occurs on the ice due to microbial consumption; however, the results are not conclusive and a subsequent sampling campaign to collect more samples is scheduled for 18-25 February 2023.

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-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.

20-EPN-048: Effect of disperse grain size distributions on the aeolian remobilisation of volcanic ash

Visit by Allen Fries, University of Geneva (Switzerland) to TA2.4 Planetary Environment Facilities (PEF), AU (Denmark)
Dates of visit: 13-17 June 2022

Report summary: Thanks to the collaboration between the University of Geneva and the University of Aarhus through the Europlanet Research program we performed a set of experiments on the remobilisation of volcanic particles. Since removal processes of volcanic particles are relatively poorly characterised, these experiments represent a unique opportunity to study the dynamics of aeolian processes. The obtained results provide valuable information on the threshold friction velocities (i.e. wind friction velocity above which particles start to detach from deposits) of different ash compositions, fundamental for modelling and forecasting remobilisation events.

A total of 32 experiments were performed by using a setup composed of a sample plate (i.e., bed of volcanic ash exposed to gradually increasing wind friction velocities) from which particles were removed by wind and imaged using various techniques simultaneously (i.e. microscopes, and webcam)). These direct observations were combined with multiple particle collection methods to study the characteristics of remobilised particles (i.e. sediment traps and adhesive papers). A complete set of half-phi grainsize classes (from 0 to 500 μm) from 4 volcanoes were analysed. 

Preliminary results show a relation between the threshold friction velocity and the grainsize, in agreement with erosion theories. In addition, these experiments illustrate variations in threshold friction velocities as a function of magma composition: lighter particles (i.e. rhyolite) are easier to remobilise than denser particles (i.e. basalt). These results are pioneering, systematically quantifying threshold friction velocities of volcanic ash for wide grainsize and composition ranges for the first time. 

Read the full scientific report, with kind permission from Allen Fries.

20-EPN-053: Investigation of the electrical properties of volcanic ash

Visit by Eduardo Rossi, University of Geneva (Switzerland) to TA2.4 Planetary Environment Facilities (PEF), AU (Denmark)
Dates of visit: 11-17 June 2022

The set of experiments within the 20-EPN-053 project represents a preliminary step towards the characterisation of the electrical properties of volcanic ash in a collaboration between the University of Geneva and the Aarhus University. This topic is fundamental to better understand aggregates formation in a volcanic eruption and improve model forecasting.

The main setup consists of a horizontal wind tunnel where a recirculating flow allows volcanic ash of different sizes (e.g. from 1 μm to 500 μm, sieved in intervals of half-phi on the Krumbein scale) and compositions (e.g. from basaltic to andesitic) to be resuspended and collide together. Single particles and aggregates are filmed during their motion in the wind tunnel by means of a High Speed Camera (HSC) placed crosswise to the main flow direction. In addition to this, a set of four Optical Particle Counters (OPCs) are located at different heights downwind to the flow (i.e. 5 cm, 10 cm, 25 cm, 50 cm) with the goal of capturing differences in particle population for very fine ash (i.e. <40μm) due to electrostatic phenomena.

The primary goal is to detected particle trajectories that will be later used to quantify the bulk charge carried by single particles by means of an inversion of the equation of motion. The secondary goal is to understand if OPCs can be used combined with the wind tunnel facility to reveal a change in particle population on the recorded histograms that can be associated with aggregation processes due to the electrostatic force.

Read the full scientific report, with kind permission from Eduardo Rossi.

20-EPN-069: Exomars Dust Sensor 22 Characterisation

Visit by Andrés Russu Berlanga, Carlos III University of Madrid (Spain) to TA2.4 Planetary Environment Facilities (PEF), AU (Denmark)
Dates of visit: 29 November 21 – 3 December

The Dust Sensor (DS’22) is designed to measure the parameters that determine in situ the size distribution of suspended dust on the surface of Mars. The sensor module is composed of an IR source and two IR detectors based on Lead Sulphide (PbS) and Lead Selenide (PbSe) active elements. These materials are defined by the integration of two spectral filters, band 1 operates in the range 1-3 µm (PbS), and Band 2 operates in the range 3-5 µm (PbSe). The Dust Sensor is part of the Radiation and Dust Monitor (RDM), one of the atmospheric devices of the METEO instrument that will be launched on the Exomars’22 mission led by ESA,

The use of the DENMARK – AU Planetary Environmental Facility is a unique opportunity to obtain experimental measurements in a reproduced condition found at the surface of Mars. The tests campaign has been developed for wind speeds of 2, 7, and 13 m/s; DS’22 has been tested in a temperature range between 5 and -55 °C, and three different positions in relation to the wind direction have been tested. The test campaign has approximately 100 independent campaigns where 5 different types of dust have been used, with various particle distributions.

Thanks to all this information, it has been done a characterization of DS’22 and will help to determine the dust distributions that will be observed during the mission.

Read the full scientific report, with kind permission from Andrés Russu Berlanga.

20-EPN-007: Investigating mantle heterogeneity through high spatial resolution mineral Pb and Nd isotopic analyses

Virtual visit by George Cooper, Cardiff University, Wales (UK) to TA2.1 VU Geology and Geochemistry radiogenic and non-traditional stable Isotope Facility (GGIF).
Dates of visit: 22 February – 09 December 2022 (10 days remote access)

Report Summary: The traditional approach of measuring the isotopic compositions of mid-ocean ridge basalts (MORB) is problematic because MORB is homogenised prior to eruption, and therefore does not record the full heterogeneity of the mantle source. To overcome this problem, we developed low- concentration coupled Pb-Nd isotope analysis of minerals at high spatial resolution to assess the isotopic heterogeneity of melts delivered to Earth’s oceanic crust and hence that of the depleted upper mantle. We acquired small volume Pb and Nd isotope analyses from minerals in gabbroic cumulates from fast-spreading oceanic crust at Hess Deep using the Thermo Scientific TRITON Plus at the Vrije Universiteit in Amsterdam. We measured minerals from 27 samples (Nd from 25 cpx and 19 plag, Pb from 18 plag) covering the full stratigraphic depth (4350 m to 25 m) of the Hess Deep oceanic crust. Our study reveals that Pb isotopes from primitive plagioclase domains show greater heterogeneity than Nd isotopes from plagioclase and clinopyroxene, validating the new coupled Pb-Nd isotopic approach. The Pb data do not vary systematically with depth but do show a departure in 207Pb/204Pb away from the NHRL and across the main trend of East Pacific Rise MORB that may indicate cumulate-melt mixing throughout the crust or the involvement of an exotic mantle source.

Read the full scientific report, with kind permission from George Cooper.

20-EPN-039: Deep carbon- and water-rich (C-O-H) fluids record associated geodynamic processes and impacts on planetary continental lithospheres through time

Visit by Yaakov Weiss, Hebrew University of Jerusalem (Israel) to TA2.1 VU Geology and Geochemistry radiogenic and non-traditional stable Isotope Facility (GGIF).
Dates of visits: 07-12 December 2021 and 21 August – 4 September 2022

Report Summary: ‘Fibrous’ diamonds, a fast-growing form of diamonds that often encapsulate carbon- and water-rich (C-O-H) fluid microinclusions, are a primary target for studies of C-O-H mantle fluids and how these fluids influence deep mantle processes. However, only a small amount of diamond (normally <1 mg) and even smaller amounts of C-O-H fluid microinclusions can be sampled and analyzed using conventional laser ablation approaches and mass spectrometry measurements. In the present project, we implemented a novel diamond-in-liquid laser ablation technique that was developed to overcome the sample size limitation, combined with ultra-low blank column chromatography and 10¹³ Ohm resistor TIMS analyses, to provide the first high-precision Sr-Nd-Pb isotopic compositions of C-O-H mantle fluids in diamonds from the Kaapvaal Craton in southern Africa. We successfully processed and analyzed 12 samples from De Beers Pool, 5 from Finsch and 6 from Koffiefontein mines, as well as standards and blanks. We finished processing the collected data which show exciting Sr-Nd-Pb relationships that vary between diamonds carrying different C-O-H fluids and micro-mineral inclusions. We still need to complete some data processing and calculations, as well as correlate the isotopic ratios with trace element compositions to fully understand the results and their geological significance. Nonetheless, we are certain that the outcome of this Europlanet project will have a major impact on our understanding of the origin and evolution of C-O-H mantle fluids, the transport of mobile components between different mantle (and crustal) reservoirs, and the role of deep C-O-H fluids in the global circulation of volatiles through Earths’ history.

Read the full scientific report, with kind permission from Yaakov Weiss.