21-EPN-FT1-018: Biogeochemistry in extreme environments: assessing analogues to early Earth environmental conditions in high-altitude hypersaline Andean lakes
Visit by Alexandra Rodler, Austrian Academy of Sciences (Austria) to TA1.6 Argentinia Andes (Argentina). Dates of visit: 11-16 December 2022
Microbial activity leaves fingerprints in the sedimentary record, for example, by changes in trace element and isotope ratios. If distinguishable from purely abiotic processes, these traces can potentially be used as biosignatures for geobiological and astrobiological research. Modern analogue environments are useful for better understanding traces of microbial life in the geologic record. This can help to define search criteria for potentially habitable environments on other terrestrial planets. The test site for this project is the Precambrian-analogue TA1 Facility 6 in the Argentinian Andes. This is a shallow lake system with extensive microbial mats, hypersaline conditions at slight acidity, with extreme temperature fluctuations and high-UV ray influx.
Using samples from this site, this project compares between chemically- and microbially influenced carbonate precipitation to further explore if trace element behaviour is related to biological processes, and if specific elements can be used as potential biosignatures. Furthermore, this project investigates trace element behaviour along redox gradients between hydrogenetic and diagenetic microbialite growth. To address if certain elements can serve as biosignatures, we pair petrographic/mineralogical approaches with high-resolution sampling for analysing trace elements as well as redox-sensitive elements and their stable isotopes. The results of this work are integrated in ongoing work focused on the geochemistry of carbonate phases of modern and ancient microbialites as well as the ongoing microbiological work including microbial diversity and metagenomics at this site. This ensures that the results are integrated in and compatible with these diverse fields of research.
20-EPN-24: Spectral investigation of the Makgadikgadi Salt Pans as planetary analog for ancient fluvio-lacustrine environments on Mars
Visit by Katrin Stephan and Ernst Hauber, DLR Institute of Planetary Research (Germany) to TA1.5 Makgadikgadi Salt Pans (Botswana). Dates of visit: 30 July – 08 August 2022
Sedimentary environments on Mars display evidence for phyllosilicates and salts. The identification and characterisation of such minerals within ancient lacustrine environments on Mars is key to resolving its past habitability. Due to their geologic importance and their potential to preserve bio signatures (e.g. organic compounds), such deposits are prime targets for lander missions (e.g. Mars2020 and Exomars). To identify promising investigation areas and landing sites spectrometers working in the visible-near Infrared (VNIR) wavelength range are extremely useful to identify and map the surface composition of Mars and other planetary surfaces (Mars Express Omega, MRO CRISM< Cassini VIMS, Dawn VIR etc).
The Makgadikgadi Salt Pans of Botswana offer access to a depocenter in a closed basin that is characterised by clastic and chemical sediments. They are therefore an ideal analogue to collect in situ spectra at a terrestrial analogue to martian sedimentary deposits and to collect samples for investigation in the laboratory by other techniques (e.g. Raman spectroscopy). Katrin Stephan and Ernst Hauber (DLR) spent 9 days at the pans and measures a divers range of surfaces at 22 locations with a portable field spectrometer. For most of the measured sites and subsides (at most of the locations, several measurements were performed), samples were collected for further investigation in the laboratory. In parallel with the field measurements, we analyse satellite data to be able to tie the field data not only to laboratory measurements, but also to remote sensing data as we would do in planetary science.
20-EPN-28: 20-EPN-28: Microbial adaptation in the hypersaline environment of Sua Pan Evaporator Ponds in Botswana and implications for search for life on Mars
Visit by Claudia Pacelli, Italian Space Agency (Italy) and Alessia Cassaro, University of Tuscia (Italy) to TA1.5 Makgadikgadi Salt Pans (Botswana). Dates of visit: 12-21 July 2022
The current conditions of the Martian surface are considered prohibitive for life as we know it, due to strong radiation, highly oxidizing conditions, concentrated evaporative salts, and relatively low water activity. The Earth hosts a multitude of extreme environments whose physico-chemical properties partly match extraterrestrial planetary bodies (e.g. Mars). Such environments are defined “analogue sites” and may offer critical test-bed for astrobiological studies in characterising the physical and chemical boundaries within which life may exist on Earth and in assessing the habitability of other planets, understanding the biological mechanisms for survival in extreme environments. For example, the Makgadikgadi desert, located in north central Botswana is considered one of the largest deserts on Earth, where the salts concentration is up to 21% of NaCl. These conditions may be compared with those detected on Mars.
Here, the main aim of this Europlanet project was to collect soil samples of Makgadikgadi salt pans in order to i) understand the adaptations of microbial systems to extreme conditions in natural terrestrial environments, ii) correlate the biodiversity with the geological context. This study is of significant interest to astrobiology investigations, allowing to assess the effects of hypersaline environment on the survival potential of microorganism and to understand if hypothetical life-forms may exist or have existed on Mars, where the concentration of chlorate salts has been detected in many different locations, from 1970s.
Report Summary:
Read the full report, published with kind permission by Dr Pacelli and Dr Cassaro.
220-EPN2-85: Preservation of Organic Matter in Paleo-Mega Lakes: Implications for Martian Biosignatures
Visit by Charlotte Spencer-Jones, Durham University, (UK) to TA1.5 Makgadikgadi Salt Pans (Botswana). Dates of visit: 20-29 April 2022
The geological history of Mars indicates that this planet has transitioned between conditions that could have supported life. Extensive fluvial features on the Martian surface provides evidence for the presence of water in Martian history and suggests that Mars may have been habitable during the Noachian period (4.1-3.7 Ga). Therefore, establishing a suite of relevant and robust biosignatures diagnostic for past life remains one of the key methods for detecting extinct Martian lifeforms. Organic compounds are the fundamental building blocks of all terrestrial life and are widespread throughout the solar system with structurally diverse organic compounds detected in a range of extra-terrestrial samples.
The main aims of this fieldwork campaign (20-EPN2-085) were to collect a range of samples, including sediments, biofilms, and salts from the Makgadikgadi basin with accompanying physical data from the basin. The second phase of this study will characterise organic compounds within the samples. The outcome of this work will be to establish the key parameters that control organic compound preservation within Martian analogue environments. These results will determine biosignatures that could be identified during future Mars missions (e.g. ExoMars 2020) and thus highlight the mineralogies present that have the highest preservation potential for biosignatures.
Report Summary:
Read the full report, published with kind permission by Dr Spencer-Jones.
20-EPN-61: Life in extreme environments: Distribution and importance of far-red light driven photosynthesis to primary production in Martian-like environments
Visit by Dennis Nürnberg, Freie Universität Berlin, (Germany) and Daniel Canniffe, Liverpool University (UK) to TA1.5 Makgadikgadi Salt Pans (Botswana). Dates of visit: 10-19 February 2022
The aim of this project was to confirm the richness and abundance of chlorophyll f-containing cyanobacteria, and their ability to use low-energy light to perform oxygenic photosynthesis in Martian-like environments. This study was a follow-up to a 2019 sampling trip to the sabkhas of the Western Sahara (Morocco), for which we could show that chlorophyll f-cyanobacteria are highly abundant. Here we expanded this research by collecting samples from the hypersaline environments of the Sua and Ntwetwe Pans in Makgadikgadi (Botswana). Microbial mat and rock samples containing endolithic and hypolithic phototrophs were collected. Light microscopy on site confirmed the abundance of cyanobacteria of various morphologies in most collected samples. The microbial mat samples were especially rich in cyanobacteria, forming a 1-2 mm thick layer at various depths depending on the absorption properties of the top layer.
Preliminary analyses with high-performance liquid chromatography (HPLC) in combination with hyperspectral confocal fluorescence microscopy confirmed the presence of red-shifted chlorophylls in some of these samples but to less extent as observed in the sabkhas. Genomic DNA has been extracted and will be used for sequencing and phylogenetic analyses based on 16S rRNA and specific far-red light genes. This will allow to fully evaluate the microbial diversity and their ability to perform chlorophyll f-driven oxygenic photosynthesis. In addition, the enrichment and isolation process of new chlorophyll f-containing cyanobacteria has been started by transferring the samples to growth media of various salinity and keeping them under selective far-red light illumination.
Report Summary:
Read full report, published with kind permission by Dr Nürnberg and Dr Canniffe.
Looking for clues about water circulation on Mars in the remote Makgadikgadi salt pans of Botswana
From 18 – 28 October 2021, researchers Erica Luzzi, Jacobs University (Germany) and Gene Schmidt, Università degli Studi Roma Tre (Italy) were funded by the Europlanet 2024 Research Infrastructure (RI) Transnational Access (TA) programme to visit the Makgadikgadi Salt Pans in Botsawana. The trip was led by Fulvio Franchi (Botswana International University of Science and Technology (BIUST)) who is responsible for the Botswana Planetary Field Analogue for Europlanet 2024 RI. In this guest post, Erica Luzzi reports on the field trip.
Our trip to Botswana through the Transnational Access offered by Europlanet has given us an incredible amount of surprises.
Figure 1: View of the Makgadikgadi Salt Pans. Credit: E Luzzi
In addition to the precious data that we collected, we indeed had a life-changing experience visiting one of the most remote places on Earth. From the absolute silence in the desert, to the calm and breath-taking landscapes in the savanna, for some moments we really felt like being on another planet. Among many adventures (and misadventures), we accessed this extraordinary place on Earth, where a lot has been studied but still leaving space for many mysteries: the Makgadikgadi salt pans (Fig. 1). These dry lands occupy a broad area in the savanna of Botswana, and are characterized by a mixture of clays and sulfates with recurrent morphologies related to desiccation processes, such as mud cracks (Fig. 2).
Mud cracks in the pan, formed by dessication processes typical of playa environments. Credit: E Luzzi
This area once hosted an ancient lake which, due to paucity of water, turned into a playa, namely a dry lake bed. Such dry environments are hypothesized to have occurred also on Mars, where also the same types of minerals have been detected.
Part of a line in the pan. The deployed cable followed the truck’s footprints that were guided by the GPS. Credit: E Luzzi.
By studying an analog field site that we can touch with our hands as it is located on Earth, we can get a variety of insights that may help us to better investigate the processes that shaped Mars into the planet we observe today.
In the region of Arabia Terra, on Mars, light-toned layered deposits often associated with mounds have been widely described in literature, and among other interpretations they were also attributed to playa-like environments. The aim of our work was to analyse the subsurface of the Makgadikgadi salt pans, looking for faults where water could have circulated and then contributed to the hydro-geological cycle that led to the deposition of such deposits.
We performed an Electrical Resistivity Tomography survey in different areas of the pans (Fig. 3).
This particular type of geophysical technique consists of placing a number of electrodes in the ground, carefully spacing them at an equal distance, and then applying a known current. Each material responds to the current in a different way, and many variables can influence the resistivity (e.g. porosity, water content, mineralogy, etc.). A preliminary version of the resulting images confirmed the occurrence of faults that will be better investigated after a robust post-processing of the data.
While we are still working on it, for now we can conclude that the survey has been successful and we look forward to linking our observations with the enigmatic deposits occurring in Arabia Terra, Mars.
Read more about Erica’s experiences on this thread on Twitter:
4) The team. Our group was composed by Gene Schmidt, first author of the future paper, Fulvio Franchi, prof at BIUST, Ame Thato Selepeng, prof at BIUST, Cabelo, an MSc student at BIUST, Rachel, driver at BIUST, and me. I thank them all for this extraordinary experience. 5/ pic.twitter.com/pabwcH8eC1
20-EPN2-121: Constraining the movement of groundwater and fluid expulsion within playa environments on Mars
Visit by Gene Schmidt, Università degli Studi Roma Tre (Italy) and Erica Luzzi, Jacobs University (Germany) to TA1.5 Makgadikgadi Salt Pans (Botswana). Dates of visit: 20-27 October 2021
Across the surface of Mars there is evidence of past lacustrine and evaporitic environments found within basins and craters, where often layered sedimentary deposits and hydrated minerals are observed. However, the intensity, duration and precise phases of water cycle activity during this period remain unresolved. Although several geological processes and locations on Earth have been previously proposed as examples to describe these deposits on Mars, we lack a strong visualisation of what water activity might have looked like during evaportic stages within basins and craters. The Makgadikgadi Salt Pans of Botswana, where once the Makgadikgadi Lake existed, is a present evaporitic environment rich in hydrated minerals and water activity. It is a depression located at the southwestern end of a northeast-southwest set of graben. Faults have been previously proposed to have been pathways for groundwater to enter basins and craters on Mars, which then contributed to both the deposition and alteration of the sedimentary deposits. Thus, imaging the subsurface of a similar environment on Earth can help us to better understand how water processes on Mars might have continued as the Martian global climate became drier.
By using the already established locations of the faults to the north of the pans, we used remote sensing techniques to trace the best location of the faults underneath the pans (Figures 1 and 2). We then used electrical resistivity surveys to image 70 – 150 m of the pans’ subsurface where the faults were deemed most likely to occur. This work allows us to better understand the possibilities of what the underlying lithology of rocks within filled basins and craters might look like. Furthermore, it demonstrates the scientific importance of future missions to employ subsurface imaging techniques on Mars.
From 29 September – 6 October 2021, researchers Daniel Toledo and Victor Apestigue (Instituto Nacional de Técnica Aeroespacial (INTA), Spain) were funded by the Europlanet 2024 Research Infrastructure (RI) Transnational Access (TA) programme to visit the Makgadikgadi Salt Pans in Botsawana. The trip was led by Fulvio Franchi (Botswana International University of Science and Technology (BIUST)) who is responsible for the Botswana Planetary Field Analogue for Europlanet 2024 RI. Ignacio Arruego, Javier Martinez-Oter and Felipe Serrano (INTA) also participated in the field trip.In this guest post, Daniel Toledo reports on the field trip.
The main goal of the field campaign in the Makgadikgadi Salts Pans was to study how dust is lifted into the air. For our investigation, we used the spare units of the Radiation and Dust Sensor (RDS) from the NASA Mars 2020 mission and the Sun Irradiance Sensor (SIS) from the ExoMars 2022 mission (see Figure 1), which are designed to study dust carried in the atmosphere of Mars by measuring how sunlight is scattered by the dust particles.
In addition to giving information about the properties of airbourne dust, these instruments are also sensitive to the presence of dust devils – swirling columns of sand and dust that are a common feature of desert areas on Mars and on Earth. RDS and SIS can detect the changes over time in the sky brightness produced by a dust devil, and this offers a unique opportunity for monitoring and studying such events during the Mars 2020 and ExoMars 2022 missions. However, to be able to characterise and interpret dust devil observations on Mars, we first need to understand how dust devils affect SIS and RDS signals by thorough testing and evaluation of the instruments in Mars-like conditions on Earth.
Figure 1. (Left) RDS instrument: two sets of eight photodiodes. One set is pointed upward, with each photodiode covering a different wavelength range between 250-1000 nanometres. The other set is pointed sideways, 20° above the horizon, and they are spaced 45° degrees apart in azimuth to sample all directions at a single wavelength; a zenith-pointed camera (Skycam) with special optics is designed to measure column optical depth.(Right) SIS instrument: Five detectors pointed at zenith and with different spectral bands and Fields of View (FOVs); twelve lateral detectors (six in the ultraviolet range and six in the near infrared range) pointed sideways; a micro-spectrometer pointed directly upwards (at zenith) with a spectral resolution of 10 nanometres in the 340-780 nanometres range.
Figure 2. Dust devils observed in Makgadikgadi Salt Pans (left panel) and on Mars (right panel). A typical dust devil on Mars spans from hundreds of metres to thousands of metres in diameter, with a height one-eight times as large. Dust devils of Mars are thought to account for the ~50% of the total dust budget, and they represent continuous source of lifted dust, active even outside the dust storms season. For these reasons, they have been proposed as the main mechanism able to sustain the constantly-observed dust haze in the martian atmosphere.
To achieve this goal, we planned a field campaign from 29 September to 6 October in the southern part of Makgadikgadi Salt Pans (see Figure 3), in the Pan near Mopipi town. This location is characterised by frequent dust devil events and conditions that promote the lifting of high levels of aerosols (dust and particles) into the atmosphere.
Each day of the campaign, we set up RDS and SIS at two different locations from sunrise to sunset, separated by about 25 m, along with:
Two cameras to record panoramic videos during the campaign period.
A Vaisala weather station to perform measurements of pressure, wind direction and intensity, temperature and relative humidity.
A ZEN radiometer to measure how much light was absorbed by the dust at different wavelengths.
The objective of having the two main instruments at two different locations was observe the dust lifting events from different perspectives.
During the campaign, we observed a large number of dust devils (many more than 10) and dust lifting events produced by wind gusts (over 10). For each dust lifting, we recorded the dust devil distance, the size, duration and direction. To do this, we marked out concentric circles with radii of 25, 50, 75, 100, 125 and 150 m on the ground. 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. All the data collected for each event was key to establish the RDS and SIS capabilities for dust lifting characterisation on Mars.
The first two days of the campaign were characterised by high dust-loading conditions and frequent formations of dust lifting events produced by dust devils or wind gusts. During these two days, each dust lifting event registered by the cameras was also detected by RDS and SIS, with signals showing a sharp peak at the time when the event passed within the sensors field of view. Preliminary analysis suggests that we can infer from RDS and SIS signals the difference between dust lifting events produced by dust devils and those produced by wind gusts – an important result for the observations on Mars.
Figure 3. Map indicating the location selected for carrying out the field campaign in the southern part of Makgadikgadi Salt Pans (red square) and the village Rakops (black square) where different lodges are available.
The third day of campaign had to be cancelled due to rain. This resulted in a lower dust-loading conditions in the following days, and thus the amount of dust lifted by vortices or wind gusts was smaller compared to the first two days.
Upon return to BIUST in Palapye on 6 October, we held a seminar for staff and students titled Atmospheric science on Mars: from Earth analogues to future planetary networks.
In summary, the campaign was a complete success. Our observations have demonstrated the capability of the RDS and SIS sensors to detect and characterise dust devils on Mars. The analysis of the signals along with the information acquired by the other instruments will allow us to quantitatively establish the sensors limit of detection. In addition, the rainy episode offered us the chance to study dust lifting events in different aerosol loading conditions.
20-EPN2-046: Characterising dust lifting events using the ground-based Mars-2020-RDS and ExoMars-2022-SIS radiometers
Visit by Daniel Toledo, INTA (Spain) to TA1.5 AU Makgadikgadi Salt Pans (Botswana). Dates of visit: 29 September – 06 October 2021
Report Summary:
On Mars, the airborne dust is a critical factor that drives the weather and climate of the planet. Dust devils are thought to account for the ~50 % of the total dust budget, and they represent a continuous source of dust, present even outside the dust storms period. For these reasons they have been proposed as the main mechanism able to sustain the observed dust haze of the martian atmosphere. However, additional dust devil surveys covering long diurnal periods are needed to place quantitative constraints on the cycles of these events. In this regard, the present and future observations of the Radiation and Dust Sensor (RDS) and the Sun Irradiance Sensor (SIS), which are part of NASA Mars 2020 and ESA/Roscosmos ExoMars 2022 missions, offer a unique opportunity to monitoring dust devils at high temporal resolution from sunrise to sunset, and with an excellent spatial coverage.
The main goal of the field campaign in the Makgadikgadi Salts Pans (20-EPN2-065) was to study dust lifting events using the spare units of RDS and SIS. During the campaign (29 Sept to 6 Oct 2021), a large number of dust devils (>10) and dust lifting events produced by wind gusts (>10) were observed by RDS and SIS sensors. For each case, information on distance, size, temporal duration and direction was registered. This information along with observations made by other instruments (e.g. wind speed and direction), have allowed us to study the potential RDS and SIS capabilities for dust lifting characterisation on Mars.
