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-EPN2-051: Evaluation of physical parameters influencing the ice particle transportby wind in a Martian-like environment

Visit by Clémence Herny, University of Bern (Switzerland) to TA2.4 Planetary Environment Facilities (PEF), AU (Denmark)
Dates of visit: 16-20 May 2022

Report summary: The transport of ice by wind plays a major role in the surface mass balance of polar caps. Ice can be redistributed by wind due to (1) transport of ice particles and/or (2) transport of water vapour associated with sublimation/condensation. On Mars, although the low atmospheric density is less favourable for the transport of particles than on Earth, both dust and sand have been observed to be transported by wind. Despite ice aeolian landforms have been observed at the surface of the North Polar Cap of Mars, ice particle transport has not been directly observed on the Martian surface. Similarly, no laboratory studies of snow/ice particle transport under Martian-like conditions have been attempted thus far due to the complexity of the material.

In this study we propose to perform experiments in the environmental wind tunnel AWTSII at Aahrus University to study the ice particle transport in a wind-flow under Martian-like pressure and temperature conditions. The threshold shear velocity, which is a critical physical parameter for particle transportation, is determined by analysing the images of the samples acquired during the experimental runs as the wind speed was increased. The influence of ice grain sizes, pressure and temperature are investigated. Results will give constraints on the plausibility of wind driven ice particle transport on Mars.

20-EPN2-023: FLUME-ET: Fluidisation of mass flows by metastable volatiles on extra-terrestrial bodies

Visit by Lonneke Roelofs and Tjalling de Haas, Utrecht University (Netherlands) to TA2.4 Planetary Environment Facilities (PEF), AU (Denmark)
Dates of visit: 03-28 October 2022

Report summary: Martian gullies are alcove-channel-fan systems which have been hypothesised to be formed by the action of liquid water and brines, the effects of sublimating CO₂ ice or a combination of these processes. Recent activity and new flow deposits in these systems have shifted the leading hypothesis from water-based flows to CO₂-driven flows. This shift in thinking is supported by the low availability of atmospheric water under present Martian conditions and the observation that gully activity occurs at times when CO₂ ice is present.

We recently performed novel experiments in the Mars chamber at the Open University in the UK that have shown that this hypothesis holds; sediment can be mobilised and fluidised by sublimating CO₂ ice under Martian atmospheric pressure. However, if these experiments work on a larger scale and if these granular-gas flows are able to erode the underlying surface and can explain the formation of Martian gully systems over the long term remained unknown. Therefore, we conducted an additional series of experiments in a larger flume that test the capacity of CO₂-driven granular flows under Martian atmospheric conditions to erode sediment.

These experiments were conducted in a 4 m long flume in the Aarhus Mars Simulation Wind Tunnel. Our experiments show that CO₂-driven granular flows can erode loose sediment under a range of different slopes and CO₂-ice fractions. The results also show that incorporation of warmer sediment increases fluidisation of the mixture, reflected by an increase in gas pore pressure in the flow. These results thus prove that morphological evolution in the gully systems on Mars can be explained by CO₂-driven granular flows.

20-EPN2-066: From Geitafell volcano (Iceland) to Mars: How hydrothermal alteration of basalt can guide our understanding of habitable environments on Mars

Visit by Julia Semprich and Geoff Austin, Open University (UK), to TA1 – Iceland Field Sites, MATIS
Dates of visit: 21 September – 01 October 2022

Hydrothermal systems provide conditions and nutrients for microbial life and thus have the potential to create subsurface habitats on Mars. Characteristic minerals associated with these hydrothermal systems have been detected on Mars’ surface by spectral observations from orbit, but their formation conditions and spatial distribution remain unknown. The aim of this study was a detailed characterisation of the spatial distribution and mineral chemistry of the low-grade metamorphic/hydrothermal alteration mineralogy in an extinct hydrothermal system.

Field work was conducted at the Geitafell central volcano near Hoffell in the south-eastern part of Iceland, an ideal analogue for Mars. The focus of this research was to record spatial relationships between the basaltic host rocks and the hydrothermal alteration in the field and to sample characteristic low-grade metamorphic minerals, which have also been detected on Mars.

We collected 19 samples from different alteration zones within the hydrothermal system including veins and vesicular basalt showing a range of alteration minerals such as carbonates, quartz, zeolites, chlorite, prehnite, epidote, andradite, and actinolite. We will now be able to conduct a detailed study of the samples including petrography, mineral chemistry, and spectroscopy, which can then be used to further constrain our models of hydrothermal alteration on Mars.

We expect this research to be highly relevant to the study of hydrothermal systems on Mars and particularly for sample return once the Perseverance Rover reaches the rim of Jezero Crater, which likely exposed hydrothermally altered rocks.

Banner image: View towards Hoffellsjökull glacier. CC BY-SA 3.0 (Gummao)

20-EPN2-105: Uncrewed Aerial System (UAS) and LiDAR Survey of Relict and Active Periglacial Patterned Ground as Analogues for Mars

Visit by Paul Knightly, Northern Arizona University (USA), and Shannon Hibbard, JPL (USA), to TA1 – Iceland Field Sites, MATIS
Dates of visit: 22-31 August 2022

Uncrewed aerial system (UAS) and LiDAR surveys were performed at periglacial patterned ground sites, including polygons terrain and stone circles, in the Westfjords and Central Highlands, Iceland during the 2022 site field season. Shallow trenches (up to 1 m depth) were excavated to gather in­situ measurements and observations to determine the presence or absence of permafrost and substrate characteristics. No permafrost was observed at either site suggesting the features may be periglacially relict. The processed UAS and LiDAR data will be used to perform morphometric evaluations of patterned ground at each site and compared to previously collected and analyzed morphometric evaluations of periglacially active patterned ground in the Canadian Arctic. The objective of this work is to develop a set of morphometric criteria for distinguishing between active and relict patterned ground. The developed criteria may help inform on the current level (or absence of) periglacial activity and ice content of patterned ground on Mars.

Read the full scientific report, with kind permission from Paul Knightly.

20-EPN2-099: Bioaerosol generation at geothermal systems: Implications for the detection of biosignatures in cryovolcanic plumes at the ocean worlds

Visit by Mark Fox-Powell and Claire Batty, Open University (UK) to TA1 – Iceland Field Sites, MATIS
Dates of visit: 27 July – 09 August 2022

The aim of our project was to capture and study microscopic aerosols ejected from bubbling or geysering geothermal springs in Iceland. Our primary motivation was to understand the potential for biosignatures to become entrained within cryovolcanic plumes at icy moons, such as Saturn’s moon Enceladus, where similar bubbling of hydrothermal gases is thought to drive the formation of aerosols that are then accelerated into space. Fieldwork was conducted at geothermal systems in Iceland in July and August 2022 by a team from the Open University (UK).

We focused our aerosol sampling efforts on two locations that exhibit contrasting aerosolisation regimes: Olkelduhals hot springs, Hverageroi, which exhibit constant, moderate bubbling of geothermal gases, and Strokkur, Geysir, which experiences regular energetic geyser eruptions. Our aerosol flux monitoring showed that geothermal springs are prolific local sources of aerosols, producing fluxes orders of magnitude above background levels. We also found that aerosol production is tightly controlled by bubbling and/or eruption activity.

Successful replicate sample sets were taken at upwind locations to characterise the background aerosol environment, and at multiple downwind locations to capture geothermal aerosols. We also took samples of spring fluids, as the assumed local aerosol sources, and geothermal gases, which are responsible for driving bubbling activity. Ongoing work is investigating the chemical composition, biomass content and microbial diversity of aerosols, and the volatile profiles of geothermal gases. Our data will provide the first insights from natural analogues into the formation of aerosols within cryovolcanic plumes.

Read the full scientific report, with kind permission from Mark Fox-Powell.

20-EPN2-120: A Molecular Toolkit to Hunt and Resolve Fungal Dark Matter (FDM) in Extreme Planetary Environments

Visit by Ali Nawaz and Christian Wurzbacher, Technical University of Munich (Germany) to TA1 – Iceland Field Sites, MATIS
Dates of visit: 19 – 23 July 2022

Fungi are amazing but largely enigmatic creatures with huge diversity and biological potential in any conceivable ecosystem known so far. This holds for our planet, but this also seems true for outer space and other planetary bodies. However, we do not know what kind of extremophile fungi are or have been growing on other planets.

To have a clue, we need to explore extreme analogue sites on our planet using novel and advanced methods. Therefore, we here propose to collect and study samples from various extreme habitats of Iceland using a unique combination of Laser-microdissection of single cells and long-read sequencing to fully resolve the Fungal Dark Matter of Mars-analogue extreme sites in Iceland.

We believe that the outputs of this project will bring novel fungal species into scientific arena and the findings of this proposal will help the broader general scientific community dealing with AstroMycology in specific, and Astrobiology in general, to rightly speculate on the capabilities and limitations of microbial life in extreme environments and correlate it with the conditions of other planets.

Read the full scientific report, with kind permission from Ali Nawaz.

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-EPN2-112: Aeolian saltation at Martian pressures and below

Visit by Philippe Claudin, PMMH – ESPCI – CNRS, Paris (France) to TA2.4 Planetary Environment Facilities (PEF), AU (Denmark)
Dates of visit: 30 May – 3 June 2022

Understanding the conditions required for initiating and sustaining sand motion on Mars is important for determining wind strengths required for mobilizing widespread ripples and dunes. Our previous experimental campaign in the planetary laboratory facility of Aarhus has provided evidence for a lower than expected transport threshold and for the emergence of impact ripples at Martian-like pressures. This time, we have made use of a new grain injector set-up at the entrance of the bed, which allowed us to trigger saltation with grains impacting with the granular surface, and therefore to mimic an effective longer bed. Even with a relatively low injection rate, we were able to reach a saturated sediment flux at the bed outlet, characterised by a neutral bed (no erosion nor deposition), whereas a purely erosive regime is always observed at vanishing injection. We could measure this saturated flux varying wind velocity in Martian conditions and found that transport can be sustained at even lower values than previously reported. With the analysis of the erosion profile along the bed, we shall furthermore be able to extract the saturation length. Finally, we recorded movies of grain motion close to the bed with a high-speed camera, which will allow us to study the properties of grain trajectories in the saturated state.

Read the full scientific report, with kind permission from Philippe Claudin.

20-EPN2-092 Characterising fine-grained rims in CO chondrites to understand the mineralogy of the protoplanetary disk

Visit by Enrica Bonato, Deutsche Zentrum für Luft und Raumfahrt (DLR), Institute for Planetary Research (Germany) to TA2 Facility 3 – NHM Petrology, Mineralogy and Chemistry Facility (UK).
Dates of visit: 1-17 February 2022

Report Summary: Carbonaceous chondrites meteorites are amongst the most primitive extra-terrestrial materials available for study and can be used to understand the formation and evolution of the solar system, as they preserve components that formed and evolved in the protoplanetary disk. They are constituted by chondrules, Calcium and aluminum rich inclusions (CAIs), amoeboid olivine aggregates (AOAs) set within a fine-grained matrix. 

Matrix material can be divided in two components: inter-chondrules matrix and fine-grained rims (FGRs) which envelopes chondrules. A major question is the understanding of the relationship between these two components, as a recent study on Te and Cr isotopes concluded that they formed from different precursor materials and therefore in different locations of the protoplanetary disk. Some of the most primitive CO3s like DOM08006, NWA7892, MIL090010 were analysed with SEM-EDX and EMPA. 

A novel approach for characterisation of the modal mineralogy of the FGRs it was used in this project, which involves chemical modelling based hyperspectral imaging techniques for scanning electron microscopy (SEM) and energy-dispersive spectrometry (EDS).Moreover, preliminary interpretation of the EMPA chemical data of the FRGs were compared with data collected on the inter-chondrule matrix of the same meteorites. FGRs appears to be consistently richer in FeO throughout the petrologic range in comparison to inter-chondrule matrix, while MgO and Cr₂O₃ content is very similar.

20-EPN2-064: High-precision isotope analysis of individual melt inclusions – Reassessing the compositional variability of Earth’s mantle

Visit by Felix Genske and Misha Böhnke, Westfälische Wilhelms-Universität Münster, Institut für Mineralogie (Germany) to TA2.1 VU Geology and Geochemistry radiogenic and non-traditional stable Isotope Facility (GGIF).
Dates of visit: 14-19 November 2022

Report Summary: In a unique approach, we acquired high precision Nd isotope data on well-characterised sample sets of silicate melt inclusions (MI) from the islands of Gough and Tristan da Cunha in the South Atlantic ocean. These data were collected using a Thermo Scientific Triton Plus TIMS at the VU Amsterdam. Melt inclusions from single or multiple olivine crystals were analysed and the new data provide insights into the magnitude, origin, and mode of sampling of the isotopically diverse materials that represent Earth’s mantle. The most prominent finding of this study is the extended isotopic variability of mantle melts, indicating that the mantle itself is more heterogeneous than assumed from studies of lavas (i.e. whole rocks). Further, the new data from melt inclusions entrapped in lavas from different islands greatly extend the known isotopic variation not only from individual eruption centres but also on a global scale.

Although observed small-scale mantle heterogeneity may exist down to the meter-, perhaps even cm-scale, the former also implies that distinct isolated large-scale (100’s km) reservoirs in Earth’s mantle (and other rocky planets) may not exist. Instead, the efficiency of mantle mixing via convection with time plays a more important role than previously thought; indeed, the existence of the full spectrum of mantle heterogeneity may be captured within single eruptions. As a consequence, the significance of large-scale distinct mantle domains detected by seismic imaging is questioned by our findings.

Read the full scientific report, with kind permission from Felix Genske.

(Image: Gough Island. Credit: L Kurtze)

20-EPN2-020: Towards Prospecting Ore Deposits on Mars – Remote Sensing of the Planetary Field Analogue in the Rio Tinto Mining Area, Spain.

Visit by Jakub Ciazela and Dariusz Marciniak (Institute of Geological Sciences, Polish Academy of Sciences, Poland) to TA1.2 Rio Tinto (Spain).
Dates of visit: 17-27 March 2022

Report Summary: The Rio Tinto area hosts the largest known volcanogenic massive sulfide deposits on Earth. The team has investigated 614 sites along a river bed located 3m from each other. At each site, they investigated 5 random samples for pyrite content. The pyrite content was always estimated by 2 to 4 researchers, and the average for each site was computed. The average pyrite content in the entire investigated area is 7.0 vol.% (12.6 wt.%). We have observed two fields, 30 x 30 m, and 30 x 60 m, with average pyrite contents >50 wt.%, which should be suitable for its detection from the orbit, both with Sentinel-2 (field resolution of 10 m) and Landsat (30 m). Principle Component Analysis of the obtained spectra from Sentinel-2 gives similar results to mineralogical data retrieved in the field during the team’s geological mapping.

By establishing the test field for remote sensing of sulfide deposits in a planetary field analogue on Earth, the team will be able to determine abundance thresholds for the detection of major sulfide phases on Mars and identify their key spectral features. The results will help in 1) more efficient use of the current NIR Martian spectrometers to detect ore minerals and 2) designing new space instruments optimised for ore detection to include in future missions to Mars such as one developed at the Institute of Geological Sciences and the Space Research Centre of the Polish Academy of Sciences called MIRORES (Martian far-IR ORE Spectrometer).

Read full scientific report with kind permission of Jakub Ciazela.

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20-EPN2-015: In-situ measurement and sampling of biosignature-hosting products in support of organics detection in the context of ExoMars 2022

Visit by Marco Ferrari and Simone De Angelis, (IAPS-INAF, Italy) to TA1.2 Rio Tinto (Spain).
Dates of visit: 11-16 July 2022

Report Summary: This project aims at sampling and performing a wide set of VIS-NIR field measurements of weathering products (e.g., sulfates, clays), rocks with hydrothermal origin, and deposits showing evidence of biosignatures. To achieve this goal, during the visit the team performed 195 measurement spots with the FieldSpec 4 portable spectrometer in the range of 0.35-2.5 µm and collected 47 samples in different forms. Among all the collected samples, three of them are consistent rock blocks. This is because they will be used as a test for the laboratory model of the Ma_MISS instrument that will be able to drill them and perform the spectroscopic measurements in the borehole wall.

This campaign will also allow the team to confirm the capability of the Ma_MISS instrument to detect spectral signatures of organics in geological samples containing biosignatures. With the spectroscopic data obtained in the field and the laboratory on the collected samples, the team will build a spectral database that will be useful to the scientific community.

These activities on terrestrial analogs have proven useful for understanding life in extreme conditions and how these can be preserved in the form of biological signatures and detected by the scientific instruments that will be on board future missions to Mars.

In addition, this work helps in acquiring crucial preparation for the exploitation and interpretation of the scientific data that the Ma_MISS instrument will provide during the active phase of the mission.

Read full scientific report with kind permission of Marco Ferrari.

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20-EPN2-048: Heating effects on the spectral reflectance properties of carbonaceous chondrite meteorites

Visit by Edward Cloutis, University of Winnipeg (Canada), to TA2 Facility 5 – DLR Planetary Spectroscopy Laboratory (Germany).
Dates of visit: 28 August – 2 September 2022

Report Summary: Carbonaceous chondrites are likely derived from dark (C-class) asteroids. Sample return missions to dark asteroids (JAXA Hayabusa-2, OSIRIS-REx) will allow us to link specific meteorites to these possible parent bodies. The compositions of the sample return target asteroids (Ryugu and Bennu) are currently unknown, as are the compositions of other dark asteroids. Dark asteroids are important scientific targets because they may have delivered prebiotic organic molecules to the early Earth.To help address how we can determine the compositions of dark asteroids, particularly whether they are primitive, aqueously-altered, and/or heated, we conducted a series of experiments at PSL designed to address this.

Specifically, we performed heating experiments, in vacuum, on clay minerals present in carbonaceous chondrite meteorites, and measured their subsequent spectral reflectance properties, as well as on samples heated in previous experiments (clays, carbonaceous chondrites, carbonaceous chondrite analogues), focusing on the most diagnostic spectral feature relevant to dark asteroids – the 3 micron region hydroxyl/water absorption band. The results are still being analysed, but it appears that heating in vacuum and exposure to vacuum cause changes in the depth and shape of this absorption feature, as well as the albedo, spectral slope, and appearance of additional absorption features. The results of this study will provide important constraints into the composition and history of dark asteroids.