TP17

High-altitude Andean wetlands hold extremophilic communities adapted to live in harsh conditions (i.e. high radiation, low rates of precipitation, high rates of evaporation, high salinity, high arsenic concentration, low oxygen pressure, strong winds, or wide daily range in temperatures). They are ecologically interesting settings for understanding the limits of life upon extreme UV radiation and provide natural scenarios to advance knowledge in the evolution of early life on Earth, which emerged upon intense UV radiation due to the lack of an ozone layer in the primitive Earth’s atmosphere. In addition, the unique environmental conditions of the high-altitude Andean lakes show some analogy to Martian paleolakes of the Noachian period (i.e. about 3.5 billion years ago). Therefore, the study of the Andean microbial ecosystem could provide information about life on other planets and we may learn from the microbial survival strategies in the highest perennial lakes and ponds on Earth what happened in the past.

Here, we investigated the microbial ecology of three high-altitude hypersaline ponds from La Puna region (Argentina) showing an increasing extent of desiccation by analyzing their lipid sedimentary record. The aim was to characterize the microbial community structure and metabolic functioning of three hypersaline ponds through the molecular and isotopic (stable carbon and hydrogen) analysis of lipid compounds in their sediments. This work is the first to describe the molecular and isotopic lipid fingerprints in the sediments of astrobiologically interesting wetlands from the Andean Puna region.

We detected lipid biomarkers of cyanobacteria, sulfate-reducing bacteria, purple sulfur bacteria, and archaea in the three alpine ponds, as well as diatoms in the intermediate salinity system. We observed that the relative abundance of biomarkers related to purple sulfur and sulfate-reducing bacteria decreased with salinity, whereas those associated to cyanobacteria and archaea decreased their relative abundance in the mid-saline pond to increase it again and became both prevailing at the highest salinity. Compound-specific isotopic analysis of sedimentary lipid biomarkers revealed that carbon assimilation in the three high-altitude ponds occurred via a combination of the reductive tricarboxylic acid cycle, the reductive pentose phosphate cycle, and the reductive acetyl-CoA pathway. The use of a number of lipid compound ratios as geochemical/environmental proxies allowed the ecological reconstruction of the three lacustrine systems, where a transition along the salinity gradient illustrated the potential impact of desiccation on the microbial community structure. The molecular and compound-specific isotopic analysis of highly resistant lipid biomarkers represents a powerful tool to record those changes over time, which has great value for interpreting the paleobiology of ancient sediment deposits on Earth and beyond.

How to cite: Sánchez-García, L., Carrizo, D., Vignale, F. A., and Farías, M. E.: Molecular and Isotopic impact of desiccation in high-altitude wetlands analogous to Martian paleolakes, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-690, https://doi.org/10.5194/epsc2022-690, 2022.

Abstract

Wind-dominated landscapes can be found on all Solar System bodies with atmospheres. These landscapes record the point of interaction of the atmosphere with the solid surface in a narrow region that also correlates with where field geologists interact with a planetary body. The Altiplano-Puna of Argentina is a high altitude, hyperarid landscape with young and easily eroded deposits and high wind activity. These factors make the region an exceptional analogue for Mars and other planetary regions where wind erosion is dominant, which includes portions of Titan, Venus and Pluto. Our field studies inform our understanding of how wind affects planetary surfaces.

Figure 1. Yardangs of the Puna, carved into ash, surrounded by gravels. With young cinder cone.

Introduction

Wind erosion of planetary bodies yields a variety of landforms, including yardangs (wind-carved ridges), bedrock ridges, sastrugi (ridges formed in hardened snow), with many of these features covered or surrounded by gravels or sands (Fig. 1, ) [1, 2, 3].

These landforms are also found on Mars [4, 5], Titan [6] and Venus. The regular spacing seen in many of these wind-eroded landforms is postulated to have arisen naturally out of wind-sediment relationships possibly controlled by bedrock hardness [7] and sediment supply [8] more than pre-existing fracturing or river channels, though both of those have also been implicated [9].

Our ongoing field project in the Puna of Argentina involves field operations over 5-7 days using observations and simple instrumentation. Our methods are designed to measure the effects of current and past winds, rock properties, and erosive power of sands and gravels on yardang and bedrock ridge morphologies. We investigate the proposition that the simple action of wind on solid surfaces can lead to the complex, self-organized forms observed where wind is dominant and surfaces are erodible.

The Puna Field Site and Methods

The Puna desert is dominated by young deposits of volcanic ash [10], evaporites and basalt cinder cones. The high elevation means air density is lower about ~1/3 compared to sea level. On Mars, the lower air density leads to large and high dust devils, and similarly large dust devils have been observed during our field campaigns in the Puna [11]. The ash deposits are widespread, and often contain up to km-scale (mega) yardangs. The youngest and softest ignimbrite, called the Campo de Piedra Pomez (CPP) [10], contains abundant medium-sized (meter-scale), mesoyardangs. We visited this region in 2015, 2018 and 2019 (Fig. 1).

Fig. 2. Smoke released near a lone yardang, revealing sideways (secondary) winds.

We examined field relationships such as orientations of yardangs, rock hardness and layering. We observed differences in rock colors related to intrinsic composition as well as weathering over time. We recorded relative matrix/pumice hardnesses and subsequent variations in erosional properties. We measured locations and sizes of wind indicators such as dedos (protrusions protected by harder lithics) and scours. We observed the action of wind on a single yardang over the course of a 7-day field excursion with an array of small instruments including Kestrel anemometers, simple smoke candles and a camera (Fig. 2), and a tuft net [12]. We deployed two DJI Mavic drones across the main CPP field to obtain a 3 cm DEM (Fig. 3), which also reveals parameters such as length, orientation, and spacing.

Key Observations

Winds over the time we observed the lone yardang (Fig. 3) in 2019 were dominantly from a direction oblique to the yardang long axis orientation and previously observed primary winds. This secondary wind may impact yardang size and shape. Preliminary results from study of the drone DEM obtained in 2019 reveal a 1:1 width/spacing relationship, similar to other studies. This is ascribed to the steady operation of wind and erosive agents over time on a relatively uniform substrate. A similar ratio was found using a DEM for a portion of the Medusae Fossae Formation (MFF) on Mars.

A dark orange coating on the leeward sides of the yardangs [13] (Figs. 2 and 3) is not presently being eroded. They are likely older surfaces reflective of the slopes of the wind-eroded surfaces at the onset of yardang emergence.

Fig. 3. Drone view of CPP yardang field (DEM images obtained from higher altitude). Person for scale.

Summary and Conclusions

Field studies in the Puna have revealed that unique landforms emerge when wind is dominant. Regularly spaced features such as yardangs or ridges emerge out of the interaction between wind and bedrock. Sizes and spacings of features likely reflect rock hardness properties. The utility of simple, reconnaissance-style field campaigns is evident in the knowledge gained through our studies of the Puna.

References

[1] Blackwelder (1934), Yardangs. GSA Bulletin 45.

[2] Ward (1979), Yardangs on Mars. JGR 8147-8166.

[3] de Silva et al. (2013) Gravel-mantled megaripples of the Puna, GSA Bulletin 125.

[4] Greeley & Iverson (1985), Threshold speeds on Venus, LPSC.

[5] Kerber et al. (2011), Origin of Medusa Fossae Formation Mars, Icarus 216.

[6] Paillou et al. (2016), Radar scattering of linear dunes and mega-yardangs on Titan, Icarus 270.

[7] de Silva S. et al. (2010), Yardangs in terrestrial ignimbrites, PSS 58.

[8] Pelletier et al. (2018), Yardang development JGR 123.

[9] Dong et al. (2012), Yardangs in the Kumtaugh, Geomorphology 139.

[10] Baez et al. (2020), Puna flow dynamics, Bull. Volc. 82.

[11] Lorenz & Radebaugh (2016), Dust devils in thin air, GRL 43.

[12] Kerber et al., in prog, Puna Yardang Observations.

[13] Aulinas et al., (2015), Rock Varnish in Dusty Regions, ESP 40.

How to cite: Radebaugh, J., Kerber, L., McDougall, D., Sevy, J., Rabinovitch, J., and Lorenz, R.: Landscapes of the Argentine Puna Reveal Conditions and Processes on Wind-Eroded Planetary Surfaces, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-715, https://doi.org/10.5194/epsc2022-715, 2022.

Introduction

Sedimentary deposits developed in High-Altitude Andean Lakes (HAAL) share some extreme and environmental characteristics that made them excellent analogues for planetary geology and astrobiology research. These conditions favor the development of a diverse and abundant microbial biota that influence mineral precipitation (e.g. carbonates) and the develpoment of microbially influenced sedimentary deposits typically know as stromatolites. To recognize and differentiate stromatolites from similar laminated deposits purelly formed by chemical processes is not straightforward, and Archean stromatolites are a good example. This makes HAAL good environmental analogues to study microbe-mineral proceeses, and the associated biosignatures. The recent findings of putative marginal lacustrine and delta deposits in the Jezero crater on Mars surface highlight the potential of these systems from and astrobiology perspective. The origin and characteristics of these martian carbonates is still unknown so the evaluation potential scenarios in comparable environmental conditions may shed some light into this uncertainties.

The Laguna Negra (a high altitude lake in Catamarca Province, Argentina) is an outstaning example of HAAL where an active microbial mat system and associated carbonate deposits is well developed. These are located in the mixing zone between groundwater spring-fed pools and the main lacustrine system. The Laguna Negra is a unique natural laboratory that fulfills the environmental criteria suggested for early Earth (Archean) and Mars (Noachian) where spectrum of biotic and abiotic process can be studied improving our ability to interpret the sedimentary record on our planet and beyond.

Geological setting

The Laguna Negra is a shallow hypersaline lake where the pH of the main lake and the groundwater springs feeding the lake fluctuates between ~6 and ~8 and salinity between ~320 and ~9 ppt respectively. The mixing zone between the main lake and groundwater is oversaturated with respect to calcite and aragonite. The carbonate belt consists of oncoids, stromatolites, and laminar crusts that are spatially localized in different zones and associated to different microbial mats systems and chemical conditions. Particularly interesting are the laminar crusts, developed in a zone where no significant microbial mats has been observed, but where a diversity of morphologies and microtextures has been recorded. Although interpreted as purelly chemically precipitated, unravelling the different processes that controls this morphological varibality is still challenging.

Oncoids, Stromatolites and Laminar crusts

Oncoids represented by concentrically laminated discs, spheres, and flattened domes (cm to dm in diameter) that can coalesce to form more complex structures and are typically associated with well-stratified diatom-rich microbial mats. The external surface surface can be smooth or can show pillar-like to shrub-shaped millimeter scale protrusions and ornamentations, particularly on the side affected by wind and currents. Oncoids are partially buried and can show lateral protrusions at the sediment–water and the air–water interface. Although oncoids are sub-spherical in shape, they can show asymmetric growth (bigger below the sediment–water interface). Complex lamination is also a result of oncoid rotation, particularly by cryoturbation and bioturbation.

Although water mixing, CO₂ degassing, and evaporation are particularly important to trigger carbonate precipitation the influence of microbial mats is visible in the macromorphologies (differential growth within the anoxic zone related to metabolisms that increase alkalinity) and a diverse set of microtextures some of which are interpreted as microbially influenced.

Stromatolites more localized and represented by centimeter to decimeter-scale laminated structures (up to 25 cm) that typically have a planar or laminar to columnar shape. They are observed associated with dark colored microbial mats and usually are encrusting the upper surface of oncoids. The columnar structures are usually centimeter-sized. Internal lamination is irregular, overlapping, crenulated-micritic to micro-peloidal laminae that preserve abundant organic remains. These features are suggestive of microbially influenced texture.

Laminar crusts show a patchy distribution and represented by millimeter to decimeter carbonate crusts encrusting volcanic rocks, peloidal sediments as well as organic remains. Can also develop dome-shaped morphologies showing concentric growth patterns. These concentric structures can be slightly assymetrical, showing preferential growth towards the upper half (as opposed to oncoids). Oriented and elongated structures are common (by wind-driven currents in the lake). Plates and domes can be rotated and/or coalesce to form more complex structures or more extensive platforms along the lakeshore. The surface can be smooth or show dendritic to pustular patterns or protusions as well as travertine-like microterracetes.

Isopachous regular laminane is the most common building block, as stated showing a concentric pattern but it is worth mentioning that the wind-oriented structures, in cross-section, develop more complex micro-textures (shrub-like to dendritic/micro-stromatolite microfabrics) that resemble microbially influenced structures.

Given the absence of microbial mats, and the macro-morphologies and micro-textures described (e.g., lamina regularity and degree of inheritance, lack of organic remains within the lamina), these structures have been interpreted as predominantly chemically precipitated carbonates, triggered by oversaturation related to water mixing, strong CO2 degassing, and evaporation.

Final considerations

Both, physocochemical and microbial processes can contribute to a diverse range of morphologies and carbonate microtextures and it is not easy to urvanel their relative contributions. Oncoids, stromatolites and laminar crusts show some distinctive features that suggest some of the driving controls, but also some overlapping characteristics that may be difficult to discriminate. As an example, although laminar crusts generally show (in cross section) a strong lamina regularity, a more diverse set of microtextures can be produced by the influence of advective-diffusive processes, localized scarbonate precipitation, rotation due waves, and cryo-bioturbation, thus increasing lamina complexity that can be confused with microbially influenced textures. Possible origins of the carbonates recorded at Jezero crater, for example including carbonate crusts developed over the basaltic substrate, pore-vein-filling carbonate cements, reworked carbonate material, or even stromatolite-like structures. Although chemical biosignatures (trace element distribution and isotope fractionation) are central in the tool box of astrobiologists, to recognize the putative biogenicity of these carbonates it is necessary to combine chemical analysis with the information provided by the external macro-micro morphology and the internal macro and micro microfabric, something that may not be possible when dealing with rover or image based analysis on outcrops or with sample returned to Earth, where part of the context may be lost.

How to cite: Gomez, F., Matic, M., Perez Valdenegro, P., Boidi, F., and Mlewski, C.: High-Altitude Andean Lakes as Natural Laboratories for Planetary Geology and Astrobiology Research: The Laguna Negra case (Argentina), Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-822, https://doi.org/10.5194/epsc2022-822, 2022.

Abstract: This work describes a new high-altitude Mars analogue site and the stratification of microbial communities with depth within lake sediments. Understanding how microbial communities at this site change with depth may give insights into the type of metabolism that may have dominated paleolake environments on early Mars and the resulting biosignatures.

Introduction: High-Altitude Andean lakes (HAALs) are poly-extreme environments which mimic many of the physiochemical conditions present on Mars during the Noachian (4.1 – 3.7 Gya) and Hesperian Mars (3.7 – 3.0 Gya)^1,2. This combination of physiochemical conditions has led to HAALs being identified as natural laboratories for studying life under conditions analogous to early Earth and early Mars^1,3. Present-day Mars is a cold, hyper-arid planet with surface conditions incapable of supporting liquid water in most locations. However, orbiter, rover, and lander missions have uncovered extensive hydrated mineral deposits and widespread geomorphological evidence of long-lasting fluvial and lacustrine environments, which dried up in the Hesperian⁴. Following the collapse of the martian magnetosphere, conditions on the surface would have become increasingly inclement. However, lake sediments may have offered refuge against desiccation, intense ultra-violet radiation (UV), large diurnal temperature fluctuations, and reduced atmospheric pressures with biosignatures potentially being preserved following lithificaytion⁵. For this reason, the study of analogue environments and the nascent microbiome is crucial in informing targets for biosignature detection. Despite their relevance to early Hesperian Mars, the lakes of the Argentinian Puna (a plateau between 3000 – 6000 m) remain understudied⁶. Here we present the geochemistry and microbial communities associated with the lake water and sediments from the previously undescribed Laguna de Antofagasta (LDA; Catamarca, Argentina, -26.111148, -67.407338) were analysed. We demonstrated that these communities change with depth, which will aid in identifying relevant metabolisms and biosignatures to inform current and future life-detection missions. 

Methods: Lake water and cores (5 x 30 cm) were collected from five sample points located around the perimeter of LDA in April 2022 (Figure 1). For each microbial core, a sister core was collected for geochemical analyses (pH, temperature, and dissolved oxygen (DO) readings) to avoid contamination of microbial cores. Each core was divided evenly into an upper, middle, and bottom section before being stored under anaerobic conditions. The lake water samples were collected and filtered using 0.22 µm Sterivex filters, and all samples were transported to The Open University, UK at 4˚C. Pore and lake water were analysed using ICP-OES and IC analysis to collect bulk chemical and ionic concentrations. DNA was extracted using the XS buffer method⁷, and 16S rRNA gene sequencing was performed to characterise the microbial communities. In addition, Postgate B media was used during culture-dependent analysis to isolate sulphate-reducing bacteria (SRB).

Figure 1: Laguna de Antofagasta (LDA) is situated in the Argentinian Puna in the Andes (A). LDA sits at the base of the Volcán La Alumbrera lava field, Antofagasta volcanic field, Catamarca, Argentina (Image B).  Image credit: Gerardo Antonio Stoppiello.

Results: There were clear differences in physicochemical conditions as well as microbial communities between the sites. Depth correlated with temperature stability, e.g., the upper sections 0-10 cm (n=5) ranged from 2.5 – 13.0 and the bottom 20-30 cm (n=5) fluctuated between 6. 7 and 8.3˚C. pH ranged from 6.8 to 8.3 but appeared to be stable across the depth profiles (Figure 2). Microbial communities also shifted with depth; genera associated with sulfate-reduction became dominant in the bottom sections. Subsequent culture-independent analysis successfully enriched for sulfate-reducing microorganisms. Canonical Correspondence Analysis (CCA) indicated that dissolved oxygen levels, location, and pH had the greatest impact on microbial community composition.

Figure 2: Cores were separated into sections before and data were collected on temperature, pH and DO.

Implications: In line with previous works^6,8,9, the results from this study highlight sulfate reduction as a key metabolism within HAALs and Mars analogue environments. This is significant as biosignatures, and their preservation may be influenced by depth. This work also highlights that physical conditions in the shallow subsurface remain stable, avoiding many of the challenges presented to life by extreme UV, desiccation, and diurnal temperature fluctuation.

Future work: To identify how microbial communities may have stratified in martian paleolakes, simulation experiments will be performed. To replicate geochemical conditions, a novel simulant will be used in a column and microbial community structure will be monitored across depth and time.

References

[1] Cabrol et al. Geophys Res Biogeosciences. 2009;114(4):1–20.

[2] Farías et al. J Geophys Res Biogeosciences. 2009;114(G2):0–04.

[3] Mlewski et al. Front Microbiol. 2018;9(MAY):996.

[4] Carr & Head JW. Earth Planet Sci Lett. 2010;294(3–4):185–203.

[5] Grotzinger et al. Science (80- ). 2014;343(6169).

[6] Gomez et al. PALAIOS. 2014;29(5):233–49.

[7] Tillett & Neilan. J Phycol. 2000;36(1):251–8.

[8] Nixon et al. Astron Geophys. 2013;54(1):13–6.

[9] Westall et al. Astrobiology. 2015;15(11):998–1029.

How to cite: Tatton, B., Macey, M. C., Gomez, F., Schwenzer, S. P., Toubes-Rodrigo, M., and Olsson-Francis, K.: Scratching beneath the surface of a Mars analogue site: Microbial stratification in Laguna de Alumbrea, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-1152, https://doi.org/10.5194/epsc2022-1152, 2022.

In the framework of Europlanet 2024 Research Infrastructure (RI) Transnational Access (TA) programme, from 29 September to 6 October 2021 a field campaign was conducted at the Makgadikgadi Salt Pans (Botswana) [1] with the spare units of the radiometers RDS [3] (part of MEDA meteo station [2] onboard on the NASA Mars 2020 Perseverance rover) and SIS (originally selected for ExoMars 2022 METEO package).The main goal of the campaign was to characterize the impact of dust devils on the observations made by these sensors, and so to evaluate the capabilities of this instrumentation to constrain the dust lifting activity on Mars (RDS is currently operating on Mars). For each day of the campaign, RDS and SIS were set at two different locations with the following instrumentation: 1) Two cameras to record panoramic videos; 2) A Vaisala weather station to perform measurements of pressure, wind direction and intensity, temperature and relative humidity; 3) A ZEN radiometer to measure how much light was absorbed by the dust at different wavelengths.

In this work we will present the different results obtained during this campaign for which a large number of dust devils and dust lifting events produced by wind gusts were analysed. For each dust lifting, we recorded the dust devil distance, the size, duration and direction. This information along with the videos made by the cameras, helped us to establish the amount of dust lifted by the dust devil as well as their distances from the instruments. We will also discuss the implication of our results for establishing the RDS and SIS capabilities for dust lifting characterisation on Mars.

How to cite: Toledo, D., Apéstigue, V., Arruego, I., Montoro, F., Martinez-Oter, J., Serrano, F., Yela, M., Carrasco-Blázquez, I., and Franchi, F.: Investigating dust devils on Mars through the Makadikadi Salt Pans analogue (Botswana), Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-485, https://doi.org/10.5194/epsc2022-485, 2022.

Stromatolites are ideal ecosystems of microbe–sediment synergy and, therefore, represent a fundamental resource for the recognition of biosignatures and investigation of astrobiological targets with regard to environment and life interactions. Even though they are one of the oldest records of life on Earth, at present, modern occurrences of stromatolites are restricted to extreme environments, such as hypersaline lakes. This work aims to characterize stromatolite features that can be used as biosignatures, seeking to understand their morphogenetic and preservation processes. Samples were collected in Lake Ashenge, a hyperalkaline high-altitude lake located in the Tigray Region of Ethiopia.

Two distinct microfacies were observed in the Lake Ashenge stromatolites: a) columnar stromatolites; and b) bulbous stromatolites. Both microfacies feature of slightly laminated microfabric composed of intercalated thicker layers of microsparite and thinner layers of calcite micrite within which exceptionally well-preserved microbial fossils including filamentous and coccoidal cyanobacteria-dominated colonies were recognized. Columnar stromatolite layers show mostly parallel or interlaced vertical arrangements of filamentous microbes which suggest different directions of water flow, demonstrating that the spatial arrangements of microbes reflect the dynamics of the environment. Bulbous structures are composed either of colonies of shrub-like filaments along their entire length and height grading into a vertical parallel arrangement at the top. This type of arrangement suggests self-sustainability of the microbial community, improving the resistance of the structures, in order to endure physical processes in the environment such as currents and wave action or predation. All samples show extracellular polymeric substances (EPS) produced by microbes normally associated with filamentous microbes. In this context, EPS may serve to support and stabilise the biofilm and contribute to the formation of columnar and bulbous structures.

Mars 2020 Perseverance rover recorded carbonate occurrences in Martian paleoenvironments from Jezero Crater which have been compared with microbialites and tufas with the potential to preserve biosignatures similar to those found in Lake Ashenge samples. Therefore, although stromatolite morphology itself configures a macroscopic biosignature which may be detected in Mars rover images, the two scales of observation (millimetres- centimetres vs micrometric) identified biosignatures in the stromatolites of Lake Ashenge could also reflect different conditions of the dynamic environment during their development. In this regard, Lake Ashenge illustrates an important modern environment for astrobiological studies and has potential analogy to ancient lacustrine environments on Mars.

How to cite: Cardoso Dorneles, V. A., Hickman-Lewis, K., Haileselasie, T., and Cavalazzi, B.: Stromatolites from extreme environment as tools for astrobiological exploration, study case of Lake Ashenge, East African Rift system, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-1125, https://doi.org/10.5194/epsc2022-1125, 2022.

Introduction

Studying planetary field analog environments is a key point in order to define the physical and chemical parameters that favor life on Earth and other planets. Terrestrial hydrothermal springs have long been considered among the most significant planetary analogs searching for traces of life on Mars [1].

Hyperspectral data have been recognised to be more suitable for the detailed mapping and identification of rocks and minerals identification of land surface, especially for minerals [2].

Notwithstanding the technological advances, hyperspectral satellites are still poorly represented in spaceborne missions for Earth Exploration compared to multispectral ones. In this context, the Italian Space Agency (ASI) EO mission named PRISMA (PRecursore IperSpettrale della Missione Applicativa, [3]) offers a great opportunity to improve the knowledge about the scientific applications of spaceborne hyperspectral data.

PRISMA, launched in March 2019, includes a panchromatic and a hyperspectral camera with 239 spectral bands. Specifically, the PRISMA satellite comprises a high-spectral resolution Visible Near InfraRed (VNIR) and Short-Wave InfraRed (SWIR) imaging spectrometer, ranging 400-2500 nm, with 30 m ground sampling distance (GSD) and 5 m GSD for the panchromatic camera [4].

Our analysis with PRISMA images was mainly performed on an arid environment in a remote region of NE Ethiopia (Dallol; Long: 40.299351, Lat: 14.244367), representing an exceptional Mars analog due to diffuse hydrothermal alteration and the sulfate deposits evocative of past hydrothermal activity on Mars. This work aimed to obtain an identification map of minerals and their relative abundance using hyperspectral imaging to understand the potential of PRISMA as analog probe of Mars orbital instruments to detect and study possible analogs on Earth.

Study Area

Dallol is situated in the Danakil Depression, which is part of the East African Rift System. Principal geothermal features of the central crater area of Dallol are salt pillars, circular manifestations and acidic ponds. The northern and southern part is dominated by a salt dome structure and Salt pinnacles in the SW salt canyon area. The Black Mountain and the super-saline Black Lagoon, just south-southwest of Dallol, is an area of salt extrusions, geothermal manifestations and brine upflows.

One advantage of this area is that the nebulosity is generally low, in fact the image selected during the dry season has a cloud coverage percentage of less than 1%. A salt suite was deposited and re-worked by hydrothermalism in the selected site. The characteristic minerals of the area are: carbonate, halite, carnallite and bischofite, anhydrite, gypsum, native sulfur of hydrothermal origin [5; 6].

Flooding episodes from the Lake Assale to the north due to intense winds acting over the flat topography of the depression. The PRISMA SWIR Land/Water band combinations on the image selected, helped us to choose the region of interest around the Dallol area.

Operational Hyperspectral Processing

PRISMA images have three different levels of processing. Level 2C and 2D geolocated and atmospherically corrected images were used in this work and dated 21 August 2021. it is worth noticing that the images acquired on Dallol prior to the image selected for analysis had several preprocessing problems, particularly for stripe removal.

The operational hyperspectral processing is composed of three main processing steps: (1) dimensionality reduction; (2) endmember identification and (3) mineral map distribution and abundance estimation.

An unexpected result was obtained by applying an additional atmospheric correction, the Internal Average Relative Reflectance with Dark Subtraction, on the L2C image already corrected during the principal component analysis (PCA). The corrected atmospheric PCA allows better highlighting of geomorphological features.

As for step (1), since hyperspectral images are composed of hundreds of extremely correlated bands, it is possible, and indeed beneficial, to reduce the effective dimension of the input data by removing bad bands.

Step (2) was performed using the THOR Hyperspectral Material Identification (in ENVI 5.6) to identify unknown spectral signatures by comparing them with spectral libraries. This tool considers background statistics and image endmembers and can therefore provide accurate responses and spectra plots for rare or sub-pixel targets.

Finally, the Spectral Angle Mapper (SAM) and the Linear Spectral Unmixing (LSU) tools were adopted for step (3). SAM determines the spectral similarity between two spectra by calculating the angle between the spectra and treating them as vectors in a space with dimensionality equal to the number of bands. LSU is a standard technique for spectral mixture analysis that infers a set of endmembers and fractions of these, called abundances. The mineral distribution and the abundance maps are shown respectively in Fig.1 and Fig.2.

Conclusion

Six minerals have been recognised with the SAM classification from ENVI spectral library, in excellent agreement with the previous studies: carnallite, jarosite, kainite, polyhalite, gypsum and nontronite. The results confirm the mineralogical variability typical of the Dallol; in Fig.2, high mineral abundance values are shown in blue. The error calculated with the RMS is very low over the entire area of interest, except for the central zone where there are sulphur pools and therefore the presence of water does not favour this type of analysis. 

To better constrain the mineralogical mapping, future work will be conducted by a field exploration campaign to collect spectral signatures to be added to the ENVI library used, which so far could not be organised due to the ongoing civil war in Dankalia.

To sum up, the study of terrestrial analogs can provide insights into the probable presence and nature of spring deposits on Mars, as well as help develop methods for classifying them from remote sensing data. PRISMA represents a valuable satellite for distinguishing not only the geometric characteristics of observed objects, but also the chemical-physical composition of the surface of the Earth.

References: [1] Walter, M.R. and Des Marais, D.J., 1993. Icarus 101:129–143 [2] Chang, C.I., 2007. John Wiley & Sons. 10.1002/0470124628 [3] Candela, L., et al. 2016. IEEE international geoscience and remote sensing symposium (IGARSS), 253-256. 10.1109/IGARSS.2016.7729057 [4] Loizzo, R., et al. 2019. IEEE (IGARSS), 4503-4506. 10.1109/IGARSS.2019.8899272 [5] Cavalazzi, B., et al. 2019. Astrobiology, 19(4), 553-578. 10.1089/AST.2018.1926 [6] López-García, J.M., et al. 2020. Frontiers in Earth Science, 7, 351. 10.3389/FEART.2019.00351

How to cite: Mancini, F., Tullo, A., Allemand, P., and Ori, G. G.: Mineral Identification and Abundance Mapping through the hyperspectral PRISMA images on the Dallol Planetary Analog, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-983, https://doi.org/10.5194/epsc2022-983, 2022.

Introduction

The selected landing site of the ExoMars mission (Oxia Planum) [1] shows mineralogical and morphological evidence that it was characterized by a hydrothermal history and by a long duration of aqueous superficial activity [2; 3]. These factors are consistent with conditions favourable to life development. In this framework, we planned a field campaign in the Rio Tinto [4] area (Europlanet TA1 facility 2) where to perform a set of VIS-NIR measurements using our portable spectrometer. In addition, for each analyzed mineral/rock on-field, we collect a representative sample to be measured with the Ma_MISS instrument laboratory model. 

Fig.1: TA1.2 Rio Tinto, south-west Spain a very acidic 100 km river with intense red dark colour (credits F. Gomez).

The Ma_MISS instrument

Ma_MISS is the Visible and Near-Infrared miniaturized spectrometer hosted in the drill system of the ExoMars rover that will characterize the mineralogy and stratigraphy of the excavated borehole wall at different depths (<2 m) [5]. Ma_MISS with a spectral range of 0.5–2.3 μm, a spectral resolution of about 20 nm in the IR, a SNR~100, and a spatial resolution of 120 μm will accomplish the following scientific objectives: (1) determine the composition of the subsurface materials; (2) map the distribution of the subsurface H₂O and hydrated phases; (3) characterize important optical and physical properties of the materials (e.g., grain size); (4) produce a stratigraphic column that will provide information on the subsurface geology. Ma_MISS will operate periodically during pauses in drilling activity and will produce hyperspectral images of the drill’s borehole.

Field activity

During the field campaign, we perform a set of VIS-NIR (0.35 – 2.5 μm) measurements using our ASD FieldSpec4 portable spectrometer on biosignatures-bearing rocks and acidic alteration products. For each selected lithotype we collect several reflectance spectra using solar light as the light source and a 99% Spectralon target as a reference in the VIS-NIR range, with particular attention to those that hypothetically host organic matter in the form of bacterial communities. In addition, for each measured mineral/rock we collect a representative sample to be used for the laboratory measurements with the Ma_MISS laboratory model. With this setup, it is possible to perform measurements with samples in different configurations (powders, slabs, or holed rock blocks); hence, we collect samples with different specific dimensions. In the case of incoherent sediments/salts, we sample a minimum amount of 20-30 g. On the contrary, in the case of coherent samples, we collect blocks with a maximum size of 10x10x10 cm, which are the optimal dimensions useful for performing the drilling operations and in-hole measurements with the DAVIS setup [6,7]. For each collected sample, we record the following data at the time of collection: imagery of the context and the sampling site with a reference scale, the three-dimensional orientation of the sample, and the geographic coordinates at the collection point using a GNSS dual-frequency GPS. Every sample is sealed in a specific container to avoid any contamination [8]. The samples’ metadata are registered in the System for Earth Samples Registration (SESAR) for long-term archival of the physical samples which can be retrieved from a unique ISGN code (isgn.org) for referencing in this and future projects.

Laboratory activity

The collected samples were measured with the DAVIS (Drill for Analogues and Visible-Infrared Spectrometer) setup at the INAF-IAPS laboratories. This laboratory facility is constituted by a drilling tool that reproduces the ExoMars Drill functionality (Laboratory Drill, LD [6]) and by a measurement tool, reproducing Ma_MISS optical characteristics (Ma_MISS Optical Tool, MOT [7]). Consisting of spare elements of the flight instrument, the DAVIS setup can be considered an instrument completely comparable to the one that will investigate the Martian subsurface. For this reason, the measurements on the collected samples become very important for instrument characterization and future data interpretation. The collected sample blocks are drilled to obtain a hole with the same characteristics as those that the ExoMars drill will do on Mars. Finally, we perform a series of in-hole spectral scans to characterize the chemical-physical properties of the collected samples. The data collected on-field and in the laboratory are analyzed and compared to reconstruct the composition of the analyzed samples. We will focus our efforts on any spectral signature related to the presence of biomarkers in the collected data since we know that the Ma_MISS tool can aid in detecting organics [9] in the Martian subsoil, which is one of the main scientific objectives of the ExoMars mission.

Conclusions

In this work, we describe the procedures followed during our geological field analysis campaign in the Rio Tinto area. This geologically/biologically well-documented site with its rock/water/biology interaction represents an ideal open-air laboratory where to collect spectral data and samples useful for testing the ExoMars/Ma_MISS spectrometer. The scientific results obtained by this and previous works made with other drilling equipment [10] and with other scientific instruments [11] confirm that this type of activity in the Rio Tinto area site is important for enriching the scientific community's grasp on the Martian environment and for obtaining key information on the mineralogical and geochemical evolution of the Martian surface/subsurface. In addition, this work provides crucial preparation for the exploitation and interpretation of the scientific data that the Ma_MISS instrument will supply during the active phase of the mission. This activity is also useful for defining the priorities of the astrobiological objectives on the ground.

Acknowledgements

This work is supported by the Italian Space Agency grant ASI-INAF n. 2017-412-H.0. Ma_MISS is funded by ASI and INAF. Europlanet 2024 RI has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 871149.

References

[1]Vago, J.L. et al. (2017) Astrobiology; [2]Mandon, L. et al. (2021) Astrobiology; [3]Quantin-Nataf, C. et al. (2021) Astrobiology; [4]Amils, R. et al. (2014) Life; [5]De Sanctis, M.C. et al. (2017) Astrobiology; [6]Rossi, L. et al. (2022) 53^rd LPSC #1353; [7]De Angelis, S. et al. 53^rd LPSC (2022) #1796; [8]Cockell, C.S., et al. (2019) Space Sci Rev. [9]Ferrari, M. et al. (2020), EPSC2020-348; [10]Bonaccorsi, R. et al (2008) Astrobiology; [11]Gomez, F. et al., (2011) Int. J. Astrobiology.

How to cite: Ferrari, M., De Angelis, S., Frigeri, A., De Sanctis, M. C., Altieri, F., Gomez, F., Ammannito, E., Costa, N., Rossi, L., and Formisano, M.: In-situ measurement and sampling of Martian analogues in the Rio Tinto area in support of the Ma_MISS scientific activity, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-153, https://doi.org/10.5194/epsc2022-153, 2022.

How to cite: Tomasi, I., Massironi, M., Meyzen, C. M., Sauro, F., Pozzobon, R., Penasa, L., Santagata, T., Martìnez-Frìas, J., and Mateo Mederos, E.: Large size lava tubes as planetary analogues: the case of La Corona (Lanzarote, Canary Islands), Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-1003, https://doi.org/10.5194/epsc2022-1003, 2022.

Lava tubes on Mars hold exciting potential for the preservation of biosignatures, which may survive on geological timescales in these isolated, stable environments. To support the development of future astrobiological mission concepts, we turn to terrestrial lava tubes, host to a variety of microbial communities and secondary minerals. Following a multidisciplinary sampling protocol, we retrieved biological, molecular, and mineralogical data from several lava tubes in Iceland. We report on blue-colored copper-rich secondary minerals and their associated bacterial communities using a multi-method approach, and an amalgam of 16S rRNA gene sequencing, Raman spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy data sets. We found numerous bacterial genera known for their high metal resistance and ability to survive in low-nutrient environments. Both are characteristics to be expected for any potential life in Martian lava tubes, and should be considered when checking for contaminants in Mars mission preparations. Associated with the microbial mats, we identified several types of copper-rich secondary minerals, indicating localized copper enrichments in the groundwater, possibly stemming from overlying ash deposits and nearby hyaloclastite formations. Molecular analysis revealed carotenoid signals preserved within the copper speleothems. If found in Martian lava tubes, blue copper-rich mineral precipitates would be deserving of astrobiological investigation, as they have potential to preserve biosignatures and harbor life.

How to cite: Kopacz, N., Csuka, J., Baqué, M., Iakubivskyi, I., Guðlaugardóttir, H., Klarenberg, I. J., Ahmed, M., Zetterlind, A., Singh, A., ten Kate, I. L., Hellebrand, E., Stockwell, B. R., Stefánsson, Á. B., Vilhelmsson, O., Neubeck, A., Anna Schnürer, A., and Geppert, W.: Blue biotopes in Icelandic lava tubes: analog environments for subsurface life on Mars, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-558, https://doi.org/10.5194/epsc2022-558, 2022.

While glacial systems are well established as susceptible environments to climatic alterations, they also offer a set of extreme conditions that are optimal for habitability studies and to interrogate the limits of life. In these settings, indigenous microorganisms must endure a prolonged exposure to cold temperatures and to background radiation for geological timescales. Therefore, glaciers and the surrounding cryo-environments (permafrost, glacial lakes or melting streams) arise as relevant scenarios to examine the development of functional microbial cryo-ecosystems and may have implications in the search for past or extant life in icy worlds beyond Earth.

Among the multiple perspectives from which thermal susceptibility can be measured, lacustrine systems effectively archive paleoenvironmental information due to their high sedimentation rates and organic matter content. Thus, polar lakes exposed to glacial or periglacial conditions are expected to contain a thriving biology that responds to not only a continuously oscillating level of nutrients, but also to a set of extreme conditions (subzero temperatures and high UV flux) that may geochemically and environmentally resemble potentially habitable locations of the Solar System such as the Martian poles or the subglacial water bodies enclosed in the satellites Europa and Enceladus.

The permanent ice sheet in Greenland represents a possible analog of the icy worlds, constituting an important long-term repository of psychrophilic microorganisms. Around it, different geological formations such as glacial lakes, permafrost or further peat soils represent a diverse degree of geobiological succession upon the influence (and retreat) of the ice sheet due to its thermal destabilization. Investigating molecular and isotopic lipid biomarkers of microorganisms inhabiting different cryo-ecosystems at and around the Greenland glacial structures may help obtain insights as of the type of life that could potentially arise on analogous extraterrestrial cold environments (ice sheet). Moreover, it could give clues on cryo-ecosystem evolutionary processes (biological succession) that are triggered when the ice cover retreats and gets exposed to the atmosphere (giving rise to glacier-melting streams, bedrock-erosion sediments, lake sediments and glacial soils). In particular, the focus of our studies is set on exploring the organic geochemistry of sediments in polar lakes representing nearby glacier-influenced ecosystems (glacial lakes) versus meteoric lakes representing longer time-exposed and further developed lacustrine and soil ecosystems (non-glacial lake).

Here, we present preliminary results of a biogeochemical study in a meltwater and meteoric lake system within the Kangerlussuaq region by the West coast of Greenland,  representing an advanced state of succession in the thermal exposition gradient of the territory. We employed molecular (lipid biomarkers) and compound-specific isotopic analyses to define ecological (microbial community structure) and metabolic (carbon assimilation-related) fingerprints in this (relatively) long exposed glacial system  compared to more recently exposed lakes in Greenland. Ultimately, we aim to learn about the microbial strategies to adapt to the ever-changing conditions caused by glacier retreat at the aforementioned molecular and isotopic level. The ubiquity of lipids as basic cellular membrane compounds and their recalcitrant hydrocarbon skeletons render these molecules a solid biomarker candidacy for the study of organic matter and habitability in the context of ecology and astrobiology, respectively.

Overall, the combination of lipid biomarker analysis and carbon isotopic studies on sediment samples of polar lakes supports the establishment of reliable lipid biomarkers in a cold, extreme environment, as well as their potential psychrophilic biosource. At the same time, determining the lipid content and their metabolic biosynthetic pathways builds a comprehensive perspective on the extent of the influence of environmental changes on the organic matter content in climatically susceptible environments.

How to cite: de Lucía Finkel, P., Carrizo, D., Parro, V., and Sánchez-García, L.: Ecological paleo-reconstruction of polar lakes in Greenland based on molecular and isotopic analysis of lipid biomarkers, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-938, https://doi.org/10.5194/epsc2022-938, 2022.

Phosphorus is a key element in all forms of life. However, P on Earth is scarce as it is locked in low solubility phosphate minerals, raising the fundamental and long-lasting question about where early life got its P supply. Hydrothermal vents or extremely acidic hot springs have been commonly investigated as favourable environments for the emergence and evolution of primitive organisms. More recently, carbonate-rich lakes have been proposed to concentrate enough dissolved P to favour the formation of life (Toner & Catling 2020), thus providing a plausible solution to phosphate supply. 

In this study, we investigate P recycling and bioavailability in carbonate and iron-rich Archaean deposits (~3 Ga) to expand our understanding of the possible origin of life on Earth, and to test the astrobiological implications on other terrestrial planets, like Mars. Unlike Earth, carbonates on Mars are scarce (Bultel et al., 2019). Interestingly, the Jezero crater, where the rover Perseverance is currently searching for sights of ancient life, is one of the few locations showing abundant carbonates on Mars (Horgan et al., 2020). Thus, these Archaean deposits serve as a Jezero crater analogue for early life on Earth. 

Phosphorus recycling is driven by the redox chemistry of the water column. Accordingly, this study will explore the prevailing redox conditions (oxic-dysoxic, ferruginous and/or euxinic), and their fluctuation, in the water column at the time of deposition. This is important because ferruginous conditions may promote P fixation in the sediments due to the drawdown of iron particles and organic matter. By contrast, euxinic conditions may enhance the flux of bioavailable P in the water column due to the degradation of organic matter and the dissolution of Fe oxides, both effective P carriers to the sediment. 

To better approach P bioavailability in these carbonate and iron-rich deposits, combined geochemical analyses and biogeochemical modelling are used. On one hand, coupling iron and phosphorus speciation geochemical techniques allow for the sequential extraction of different forms of Fe and P and serve to quantify their concentrations (Poulton & Canfield, 2005; Thompson et al., 2019). On the other hand, biogeochemical models allow for the understanding of Ca-Fe-S-P interactions within variable redox conditions. 

Iron speciation results will determine whether the studied carbonates were deposited under euxinic or ferruginous conditions, relative to total iron (Fe_T), and will track the redox evolution upward stratigraphy. Phosphorus speciation results will quantify different operationally defined P sedimentary pools, including iron associated (P_Fe), authigenic (P_auth), detrital (P_det), organic (P_org) and total (P_T). Subsequently, Fe and P results will be modeled to address two fundamental research questions: a) shifts from ferruginous to euxinic conditions promoted the accumulation of dissolved phosphate, and b) iron reduction (microbial or abiotic) favoured the increase of alkalinity, contributing to carbonate precipitation. 

Paleoenvironmental reconstructions of early Earth play a key role in unravelling the co-evolution of life and the Earth system. Our understanding of the biogeochemical evolution of the P cycle during the Archean may shed light on whether carbonates on early Mars could have accumulated enough dissolved P to become favourable environments for the emergence and evolution of life. 

References: 

Bultel, B. et al. (2019). Journal of Geophysical Research: Planets, 124, 989–1007. 

Horgan, B. et al. (2020). Icarus 339, 113526. 

Poulton, S. W. & Canfield, D. E. (2005). Chemical Geology, 214, 209–221. 

Thompson, J. et al. (2019). Chemical Geology, 524, 383–393. 

Toner, J. D. & Catling, D. C. A. (2020). PNAS. 117, 883–888. 

How to cite: Cañadas Blasco, F. and G. Fairén, A.: Phosphorus Cycling and Bioavailability in Archean Carbonates: Analogues for Martian Paleoenvironments, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-311, https://doi.org/10.5194/epsc2022-311, 2022.

Introduction: Sedimentary volcanism if ever operated on Mars would be a potentially interesting target for investigation by future landing missions for understanding volatile and sediment migration in the crust and the potential for astrobiology [e.g., 1, 2, 3, 4]. In order to support the argument for conducting such missions, deeper understating of the mud volcanism and their biological environment in terrestrial analogs are desired. Here, we report about our research activities on various mud volcanism types (e.g., large and small scales, low and high temperatures, active and fossil) from terrestrial analog sites (one site in Azerbaijan and three sites in Japan). The investigations are conducted in extensive collaborations with a number of other research groups.

Ongoing studies at terrestrial analog sites: We list here terrestrial analog sites where we have been studying to provide insights on geological (physical and chemical) processes and astrobiological implications of sedimentary volcanism that may have operated on Mars.

Azerbaijan: This country along the Caspian Sea hosts some of the best and largest examples of mud volcanoes on Earth [5, 6]. There is a great variety of MV morphologies observed in the area (Fig. 1) and these MVs have been utilized as terrestrial analogs for identifying possible SVs on Mars [e.g., 7]. However, the genetic factors controlling the formation of MVs have not been well understood and the approach in physical volcanology would be useful for revealing their formation mechanisms. A systematic morphological/morphometric survey of MVs in the world including those in Azerbaijan has been considered [8].

Fig. 1. Summit crater of Bozdag-Guzdek, an approx. 3-km wide mud volcano in Azerbaijan [7]. The grey-color material on the right represents the front of a mud flow erupted recently.

The Goshogake mud volcano field: This MV field in northern Japan is characterized by high-temperature (33–98 °C), acidic (pH 2.44–2.94) fluids with the influence of nearby magmatic volcanism (Fig. 2) [9, 10]. The presence of high-temperature silica polymorphs and/or microcrystalline opals, and an amorphous form of silica in the mineralogy indicates that the mud volcano system likely involves conditions and processes such as high temperature, hydrothermal circulation, dehydration reaction at certain depths underneath the Goshogake mud volcano field. The emitted gas phase includes CO₂ and hydrocarbons such as methane, and it is considered that at least part of the erupted mud has a sedimentary origin. Beside characterization of the geological properties of the field, we are in the process of evaluating possible biomarkers within the mud fluids [11].

Fig. 2. Mud pots spewing hot and acidic fluids together with carbon dioxide and methane gasses in the Goshogake mud volcano field, northern Japan [9, 10].

Mud volcano vents in Tokamachi: There are MV vents distributed in the area of Tokamachi, central Japan. There are four vent sites of particular interest that are emitting methane gas at high concentration levels (Fig. 3). The total methane emission was estimated to be least 20 ton/year, of which more than half was from invisible seepage surrounding the MV vents [12]. The mud is derived from a deep subsurface deposit of marine sedimentary origin. Our microbiological investigation of the MV fluids recently characterized a methane-related ecology associated with these on-land MV vents in a sedimentary setting, which can be applicable to Mars analogs [13].

Fig. 3. This vent in Tokamachi, central Japan is emitting mud and methane gas [12, 13]. 

Fossilized MVs in Wakayama: There are field sites along the coasts of Kii Peninsula, western Japan (Wakayama Prefecture), where ancient mud volcanism is preserved and exposed in sedimentary sequences [14]. Here, coarse-grained shallow marine sediment sequences of the Miocene upper Tanabe Group and Kumano Group are intruded into by the underlying fine-grained sediment. The intruding mudstone deposits exhibit diverse types of stratigraphic features: mud dikes intruding into overlying layers (Fig. 4), diapirs in contact with surrounding strata. Fine-grained sedimentary materials have the potential to preserve biosignatures [15]. Thus, our ongoing investigations include search for biomarkers in the preserved mud dykes or diapirs [11], which is likely to shed light on the similar study for future landing missions in purported mud volcanoes that are now extinct.

Fig. 4. A mud dike intruding into the overlying layers. Wakayama, western Japan [14].

References: [1] Komatsu G. et al. (2014) LPSC 45th, Abstract #1085. [2] Oehler D. Z. and Allen C. A. (2012) SEPM Sp. Pub., 102, 183–194. [3] Dohm J. M. et al. (2011) In: Analogs for Planetary Exploration, GSA-SP 483, p. 317–347. [4] Wilhelm M. B. (2019) AGU, Abstract #P41C-3447. [5] Aliyev Ad. A. et al. (2009) Catalogue of mud volcanoes eruptions of Azerbaijan (1810-2007), Nafta-Press, 106 p. [6] Guliyev I. S. and Feizullayev A. A. (1997) All about mud volcanoes, Nafta Press, 52 p. [7] Komatsu G. et al. (2016) Icarus, 268, 56-75. [8] Oppo D. et al. (2020) LPSC 51th, Abstract #1041. [9] Komatsu G. et al. (2019) Geomorphology, 329, 32-45. [10] Komatsu G. (2019) Science Trends, https://sciencetrends.com/where-mud-meets-magma/. [11] Ishimaru R. et al., in preparation. [12] Etiope G. et al. (2011) Appl. Geochem., 26(3), 348-59. [13] Miyake N. et al., in submission. [14] Komatsu G. et al. (2019) LPSC 50th, Abstract #1149. [15] Komatsu G. and Ori G. G. (2000) PSS, 48/11, 1043–1052.

How to cite: Komatsu, G., Ishimaru, R., Miyake, N., and Matsui, T.: Terrestrial analog studies of sedimentary volcanism: Application to Mars science and missions, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-468, https://doi.org/10.5194/epsc2022-468, 2022.

The mid-latitudes of Mars host a large amount of buried ice deposits [1], which bear a record on the very Late Amazonian climate evolution (~10⁷ to 10⁸ yr.) [2] and are a possible resource for future exploration [3]. The reconstruction of the history of these ice reservoirs and the characterization of their current state is critical to enable putting constraints on the interplay between climate change, volatile migration and landform evolution. Examination of terrestrial analogs can help to identify similarities and – equally important – differences between the response of buried ice on Mars and Earth to changing environmental parameters. Here we report on our long-term investigations of an ice-cored moraine on Svalbard, a proxy for mid-latitude debris-covered glacier on Mars [4].

Our study area is an ice-cored lateral moraine of Kongsvegen glacier on the southern shore of Kongsforden in NW Spitsbergen (Svalbard). This site is subject to rapid degradation by melting and redistribution of surficial sediment, e.g., by thaw slumps and debris flows [5]. We couple multi-year fieldwork with repeat remote-sensing observations. Fieldwork includes DGPS-supported monitoring of surface changes by several imaging methods comparisons to environmental data (e.g., [6]). In 2008, a flight campaign with HRSC-AX (an airborne version of DLR’s High Resolution Stereo Camera on Mars Express) provided orthoimages (20 cm/px) and a Digital Elevation Model (DEM; 50 cm ground sampling distance, GSD) [7]. In 2020 a repeat campaign with DLR’s MACS (Modular Airborne Camera System) achieved ground pixel sizes between 5 cm and 10 cm for RGB images, and 10 cm to 15 cm for NIR images. The associated DEM has the same resolution [8]. MACS also acquires TIR data,which we use to identify regions with anomalous temperatures (e.g., exposed ice). We use for detailed mapping of ice-rich viscous flow features on Mars [9]. This study focuses on the Nereidum Montes area in the northern part of the Argyre basin. Image analysis, mapping of landforms and documentation of results were carried out using the QGIS software.

A difference DEM was generated to determine the elevation differences (i.e. volume changes) on the ice-cored moraine between 2008 and 2020. Hillshade layers were created for each dataset to facilitate quick visual identification of morphological changes. Slump scars were digitized in 2008 and 2020 on orthoimages and hillshade views, and prominent slumps of 2020 (most recent, visible and best preserved) have been geomorphologically mapped with a focus on buried dead ice, collapsed sediment, and the relative activity of mud flows. Image analysis and mapping of Martian landforms is currently ongoing.

There are 4 areas of major activity within the ice-cored moraine (Fig.1.a) highlighted by the four red boxes b, c, d and e, with more than 10m of elevation losses. There are many areas showing a neutral balance in terms of topographic evolution (white pixels). Hillshade layers from 2008 (Fig.1.f) and 2020 (Fig.1.g) correspond to the area of box d and show that significant changes have occurred in 12 years, indicating a massive degradation of ice-cored moraine in the last decade. This also demonstrates that the general trend is towards a heterogenous loss of material. The slump scars appear to be concentrated in the same areas described above. In 2008, 85 scars were counted against 157 scars in 2020, i.e. almost twice as many. It also appears that the 2020 scars are following the outlines of high activity areas while the 2008 scars are within these areas.

Regarding the detailed mapping of slumps, the area corresponding to the buried dead ice, mapped with the TIR channel, can vary in shape and size depending on the shape of headscarp and the other units, i.e. the collapsed sediments and the mudflows (Fig.2.b,d). The collapsed sediments are washed away by the mudflows. The mudflow seems more active near the previously exposed dead ice. Therefore, the degradation of ice-cored moraines takes place mainly through the melting of the ice, which leads to mass wasting and rapid degradation. As Mars does not have the same climatic conditions, it is interesting to see whether the same landforms can be found on it at a very local scale.

The Mars case study displays gullies, arcuate ridges with small gullies superposed on their slopes, flow features and also possible sublimation features such as pitted terrain, broad pits, and lineated patterned ground (Fig.3.b). The area is also filled with washboard terrain which is only found at steep slopes, above the lobate flow feature. It is marked by a close alternation of closely-spaced scarps which are parallel to the contour lines (possible evidence for paraglacial sacking [10]). Tension cracks are also found at the ridges and parallel to gully headscarps indicating recent activity. These tension cracks may be similar to headscarp retreats on backwasting processes on ice-cored moraines (Fig.3.d). The ice-cored ridge or arcuate ridge may still undergo degradation. The first results show that the degradation processes are rather related to potential ice sublimation and that signs of melting ice, if they exist on Mars, are not strongly encountered, which is consistent with the studies on very Late Amazonian climate evolution.

References

[1] Levy, J. S. et al. (2014), J. Geophys. Res. Planets, 119, 2188– 2196. [2] Bramson, A. et al. (2021), Bull. Amer. Astron. Soc., 53(4), e-id. 115. [3] Putzig, N. et al. (2022) LPSC 53, #2443. [4] Petersen,E. et al. (2017) LPSC 48, #2966. [5] Bennett, M. et al. (2000) Geomorphology, 35, 21-40. [6] Boike, J. et al. (2018), Earth Syst. Sci. Data, 10, 355–390. [7] Hauber, E. et al. (2011), Geological Society of America, 483, 177–201. [8] DLR - Institut für Optische - Sensorsysteme, (2020). [9] Souness, C. and Hubbard, B. (2012), Progress in Phys. Geog. 36(2), 238-261. [10] Jawin, E. R. et al. (2018), Icarus, 309, 187-206.

How to cite: Desjardins, M., Hauber, E., Bucher, T., Geßner, M., Hiesinger, H., Schmedemann, N., Johnsson, A., Ellermann, F., Sassenroth, C., Brauchle, J., Conway, S., and Noblet, A.: Degradation processes on ice-cored moraines on Svalbard: a terrestrial analog for Mars, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-1035, https://doi.org/10.5194/epsc2022-1035, 2022.

Sublimation combined with wind: Volatiles (N₂, CH₄, CO₂, H₂0, NH₃) are very common in the solar system (Fig 1). The average pressure and temperature conditions at the surface of many bodies suggest that volatile ices are stable and we thus expect that solid bedforms may form on these surfaces by either sublimation and/or condensation. These mass transfers between ice and overlying atmospheres are already known as landforms-shaping processes at different scales. These processes are very effective on the Martian North Polar Cap [2], whose spirals of the MNPC are known to be the result of sublimation on one side and condensation on the other [3-4], and as Pluto, where the Bladed Terrain Deposits are associated with sublimation of N₂ and condensation of CH₄ [5].

FIGURE 1 – Superimposed phase diagrams of the predominantly represented species (N2, CH4, CO2, NH3, H2O) in the Solar System in (p,T), using the Clausius-Clapeyron relationship.

Scientific goal: To understand the process of material redistribution by the wind on icy planetary surfaces subject to phase changes, we propose a theoretical model coupling of flow dynamics and mass transfer and perform a linear stability analysis [6]. As done for loose bedforms, we use solid transverse bedforms as geomarkers to identify sublimation zones and to deduce erosion rate. We aim to physically and morphologically characterise these periodic waves perpendicular to the main flow over icy substrates and we are looking for analogues to assess the validity of our model before interpreting the observations on other bodies. On Earth, field analogues could be found in extreme cold and icy environment. Similar laboratory experiments are also suggested to complete the dataset.

Sublimation waves analogues: We have identified two possible analogues for sublimation patterns from the literature: in the Blue Ice areas (Fig 2a) of the Antarctic ice sheets [1] and in ice caves such as the Eisriesenwelt cave (Fig 2b) in Austria [7]. We also use new measurements made in a laboratory experiment on the sublimation of CO2 ice in an atmospheric wind tunnel (Fig 2c).

FIGURE 2 – Sublimation waves analogues [6]: (left: a) Blue Ice areas  (middle: b) the Eisriesenwelt ice cave (right: c) CO2 ice in an atmospheric wind tunnel.

In all these environments, linear and transverse bedforms appear. However, there are quite different in scales and involve different compositions of the icy substrate and the atmosphere. Despite those differences, the winds that flow on these surfaces are always turbulent and of infinite height and the environmental conditions are favorable to sublimation of ice: the surface temperatures are lower than the triple point and the partial pressure of the species is far from pressure at saturation. These sublimation waves have been classified as net ablation areas from surface energy balance.

Theoretical model for redistribution processes: We consider a simple 2D case of a wavy surface of wavelength l and small amplitude with an overlying turbulent atmospheric boundary layer, of height H much larger that the wavelength. The mass transfer rate varies along the profile and has a maximum somewhere in the troughs, shifted from the crests by a phase lag. This effect allows the growth of a range of wavelengths and their migration, depending on the location of the maximum. The flow is perturbed by the topography and modify the mass transfer in turn, which may lead to the instability of such bedforms.

From the stability analysis [6] we obtain 3 scaling laws: (1) the first law can predict either the friction velocity or the wind speed from a measure of the wavelength and if the viscosity is known, (2) the second law show that the migration velocity is found to scale linearly with the average value of the sublimation rates and thus depends on the kinetics of the phase transition, (3) the third law links the characteristic time of formation with the viscous length and the sublimation rate.

FIGURE 3 – Model (black line), measurements (symbols) and prediction (MNPC) for sublimation waves [6].

Sublimation bedforms as geomorphic markers: The model prediction, black line (Fig 3), is superimposed on the natural terrestrial and the experimental model. This allows us to predict either the friction velocity or the wind speed from a measurement of the wavelength for the Martian Northern Polar Cap. The values predicted are in good agreement with those obtained by the martian climate database at the same place where these sublimation waves have been detected, and those both for the frictional velocities and the wind speeds.

Conclusion: We propose a formation model for the sublimation waves by coupling mass waste with the hydrodynamic instability of the overlaying turbulent flow, in the case where the flow heigh is larger than the wavelength. The subjacent objective was to determine if terrestrial analogues exist or some experimental facilities could be used. We show it is possible to link the dimension of the sublimation waves to their environment and produce three scaling laws that links the geomorphological characteristics of these bedforms (wavelengths, migration, formation time) and the flow (velocity, viscosity, flow height). The adequacy between the observations/experiments and our model allows us to validate these environments as terrestrial/experimental analogues of sublimation waves. New experiments could thus be designed in controlled atmospheric wind tunnel like Aarhus wind tunnel, Denmark to explore controlling parameters.

Acknowledgments: Plan National de Planétologie.

References: [1] Bintanja R. (1999) Reviews of Geophysics, 37(3) :337–359 [2] Herny C. et al. (2014) EPSL, 4013, 56-66. [3] Howard A. D. (2000)Icarus, 144(2) :267–288. [4] Smith I. et al (2010) Nature, 465(7297). [5] Moore et al (2017) Icarus, 287 :320–333, 2017. [6] Bordiec M. et al. (2020) Earth & Sci. Reviews. Sci., 103350. [7] Obleitner and Spötl, (2011) Cryosphere, 5(1) :245–25.

How to cite: Carpy, S., Bordiec, M., Bourgeois, O., Herny, C., Massé, M., and Pochat, S.: Field analogues and laboratory experiments to constrain sublimation waves on planetary icy surfaces, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-1210, https://doi.org/10.5194/epsc2022-1210, 2022.

Introduction

If life ever existed on Mars, its presence on the surface was likely relegated to spatially isolated patches [c.f., Phillips et al. this conference]. It follows that finding evidence for past life on Mars will require careful selection of rover-explorable targets that are most likely to have hosted organisms at or near the surface and retained evidence of those organisms. The salt habitats of paleo-lake basins [1], [2] are examples of habitats with taphonomic windows [3], [4], and as such are high priority targets for astrobiological exploration [c.f,. Phillips et al. this conference]. Salt-encrusted paleo-lake basins on Mars [5]–[7] may contain features that in similar environments on Earth serve as habitats; however, the spatial resolution necessary to detect these features is relatively unknown [8]. Here, we show how deep-learning can be used to understand spatial resolution thresholds for the identification of habitats and apply this method to the habitats in a terrestrial salt-encrusted paleo lake basin (salar), Salar de Pajonales.

Geologic Background

Salar de Pajonales, Chile (SdP, 25°08’29”S, 68°46’20”W, 3547 m, Fig. 1) lies within the Altiplano Puna plateau near the border of the Atacama Desert (hereafter, Altiplano and Atacama, respectively). Salt-encrusted basins in the Atacama and Altiplano experience multiple extreme conditions, including aridity/hyper-aridity [9], intense UV irradiation [10], severe diurnal temperature swings, high evaporation rates [9], and high concentrations of salt, which make them suitable environmental analogs to the salt-encrusted basins of Mars. The surface of SdP hosts regions locally dominated by gypsum and carbonate [11]. Data for our study was collected from a gypsum-dominated area of the salar, designated the “Dome Field” for its many domical gypsum structures [2]. [12] show that microbial (chasmo)endoliths preferentially reside in alabaster habitats within decimeter- to meter-tall domes and ridges [c.f., Phillips et al. this conference].

Fig. 1 Overview of Salar de Pajonales (SdP). A) Location of SdP within the Chilean Atacama Desert. B) Outline of SdP, note volcano to its south. C+D) Orthophotomosaic and DEM of the Dome Field generated with drone-collected images. E, F, G) Ridge, Dome, and Patterned Ground (biological soil crust) habitast at SdP, respectively. H) Pink and green horizons show endolithic microbial communities. I) Aerial view of Domes, Ridges, and Patterned Ground (biological soil crust) at SdP. J+K) Human-mapped ground truth classifications of the 12 feature classes in our study site.

Methods

We assessed the confidence with which habitats at SdP (polygon ridges, domes, and patterned ground) could be identified over a series of spatial resolutions with a methodology based on fully convolutional neural networks (FCNs, [13]). An FCN is a convolutional neural network with at least one fully-connected layer that adapts it to the semantic segmentation task. A “Confidence Score” was formulated to represent the degree to which one should trust FCN predictions [8]. The Confidence Score takes into account the correct and incorrect predictions made by the network, as well as the certainty (calculated using the Monte-Carlo Dropout method, [14]) associated with each prediction. BF-Score, precision, and recall were also calculated.

Fig. 2 Results as a function of Ground Resolved Distance (GRD). A) Confidence Score. B) BF-Score. C) Recall. D) Precision. E) Certainty. Gray region represents the approximate range of spatial resolutions achievable with HiRISE.

Results

The general characteristics of Precision, Recall, and BF-Score values as a function of image spatial resolution were relatively consistent between the habitats evaluated (Fig. 2b-d). We interpret the sharp drops in Precision, Recall, and BF-Score to mean that a spatial threshold critical for accurately segmenting (i.e., drawing a boundary around) a feature has been crossed. The threshold occurs at a GRD ~one-third the characteristic length scale of each feature, i.e., when the feature is spanned by 9 to 12 pixels. An analogy can be made to the Nyquist sampling frequency, wherein 2 to 3 pixels are required for a feature to be detected in an image. To achieve a 1-sigma level of identification confidence (Confidence Score ≥~85%) for the PolygonRidge class, a GRD approximately 20% its length scale is required, that is, it must be spanned by 15 to 20 pixels, or 5 to 10 times more pixels than is required to detect the feature. Conversely, Domes require a GRD ~6% their characteristic length scale (spanned by 50 to 65 pixels, or 17 to 33 times its detection limit) to be identified at the 1-sigma confidence level. PatternedGround could not be identified at the 1-sigma confidence level with the spatial resolutions studied here. This pattern suggests an intuitive hierarchy of recognition:

• detection: at 2-3 pixels, it is known that a feature exists
• segmentation: at 9-12 pixels, a boundary can be drawn around the feature
• identification: at ≥ 15 pixels, a class name can be accurately assigned to the feature.

These results emphasize the complexity and feature-specific nature of establishing identification thresholds in spatial resolution, and show that assuming the identifiability of a feature based only on its size may lead to overconfidence in the ability to identify it (e.g., the Dome class).Extending this work to establish the most- and least-identifiable habitats within presently-available images of Mars would be key for triaging habitats into a prioritized list of astrobiology targets and for informing future instrument specification requirements.

References:

[1]       A. F. Davila et al., 2008. doi: 10.1029/2007JG000561.

[2]       N. W. Hinman et al., 2022, https://www.frontiersin.org/article/10.3389/fspas.2021.797591

[3]       R. E. Summons et al., Astrobiology, vol. 11, no. 2. p. 157, 2011.

[4]       D. C. Fernández‐Remolar et al., 2013. doi: 10.1002/jgrg.20059.

[5]       M. M. Osterloo et al., 2008. doi: 10.1126/science.1150690.

[6]       T. D. Glotch, et al., 2016. doi: 10.1002/2015JE004921.

[7]       E. K. Leask and B. L. Ehlmann, 2022, doi: 10.1029/2021AV000534.

[8]       M. S. Phillips et al., Astrobiology, in review.

[9]       J. Houston and A. J. Hartley, 2003. doi: 10.1002/joc.938.

[10]     D. Häder and N. A. Cabrol, 2020. doi: 10.1111/php.13276.

[11]     C. Rodríguez-Albornoz, Thesis, Universidad Católica del Norte, 2018.

[12]     K. Warren-Rhodes et al., Nature Astronomy. in review.

[13]     E. Shelhamer, et al., arXiv:1605.06211. p. tran, 2016.

[14]     Y. Gal and Z. Ghahramani, ArXiv, vol. abs/1506.02142. 2016.

[15]     B. L. Carrier et al., 2020. doi: 10.1089/ast.2020.2237.

[16]     B. L. Ehlmann et al., 2016. doi: 10.1002/2016JE005134.

[17]     T. C. Onstott et al., 2019. doi: 10.1089/ast.2018.1960.

[18]     L. Hays, “NASA Astrobiology Strategy.” 2015.

How to cite: Phillips, M.: What is that? Identification confidence of Mars analog habitats with Deep Learning, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-1200, https://doi.org/10.5194/epsc2022-1200, 2022.

The European Commission (EC) is currently formulating their vision for future research infrastructures (RIs) and how they should deliver improved transnational access (TNA) for the broad scientific and industrial community. There is a major emphasis on ensuring RIs are self-governing and sustainable. Many of the larger, often government supported, RIs will operate as European Research Infrastructure Consortia (ERICs). ERICs are generally established around large national research facilities. The Europlanet Society has instead chosen to be a AISBL (International Non-Profit Organization) based in Belgium ensuring control by the scientific community. Upon granting of the AISBL status, expected later in 2022, the Europlanet Society will be in position to lead or co-operate in any future RI initiatives.

Based on a series of briefings by the EC, it is predicted that existing established RIs such as Europlanet will be expected to collaborate within and across disciplines to offer a wider range of transnational access. For Europlanet this will mean collaboration within the Astronomy-AstroChemistry communities Opticon, RadioNet, ChETEC, etc. In addition, future TNA programmes will be expected to involve:

• more diverse facilities;
• greater interaction with participation by industry;

• greater globalisation with an emphasis on Africa and Asia;
• more active participation from the under-represented European states.
• reduced environmental impact;

We believe that Europlanet is in a strong position to achieve many of these requirements. The next call for modified RIs that provide transnational access is expected to be launched in astronomy-space realm at the end of 2022, for calls in 2023 and 2024. It is therefore necessary to start to formulate ideas for a future TNA programme. The presentation at EPSC will give a brief review of the current status of the Europlanet 2024 RI, and is designed to initiate and stimulate discussion within the planetary community as to their wishes for future TNA facilities, specifically in light of ESA goals to return to the Moon and an increased focus on Exoplanetary science.

How to cite: Davies, G., van Westrenen, W., Merrison, J., Russell, S., Cavalazzi, B., L'Haridon, J., and Mason, N.: The Future and Sustainability of Transnational Access in Europlanet Research Infrastructure, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-126, https://doi.org/10.5194/epsc2022-126, 2022.