20-EPN2-073: Assessment of the Aeolian Dispersion and Wind Effects on Cryptoendolithic Microorganisms in the Martian Environment

20-EPN2-073: Assessment of the Aeolian Dispersion and Wind Effects on Cryptoendolithic Microorganisms in the Martian Environment

Virtual visit by Lorenzo Aureli, University of Tuscia (Italy) to TA2.4 Planetary Environment Facilities (PEF), AU (Denmark).
Dates of visit: 15-19 November 2021

Report Summary: The hostile current conditions on the surface of Mars entail that, if any form of life exists or ever existed on the planet, it may have adopted survival strategies like those evolved by terrestrial microorganisms inhabiting extremely harsh regions, such as Antarctic deserts. Here, one of the most common strategies observed is the cryptoendolithic growth, defined as the colonisation of the small interstices inside rocks, where microorganisms are protected from external hostile conditions. However, endolithic microorganisms can break down the surrounding rock substratum, thus causing the exfoliation of the external layers of the colonised rocks. Consequently, exposure to wind and saltating sand can cause the dispersal of the shallow rock fragments and endolithic colonies to the environment.

This study aimed to examine the possibility of dispersal of hypothetical rock-dwelling microorganisms on the surface of Mars. To achieve this goal, colonised Antarctic sandstone rocks were exposed to simulated martian and terrestrial windy environments at the Planetary Environment Facility in Aarhus University in four different simulations. Rock, sand and dust samples were collected after each simulation to assess the survival and the variety of dispersed microorganisms in the two scenarios. Although biological data are not available at the moment of the draft of the report, remarkable differences were observed in the dispersal of dust and sand between the different conditions.

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20-EPN-078: Abrasion test to understand aeolian grain surface evolution on Mars versus Earth – suggestions for ExoMars rover mission

20-EPN-078: Abrasion test to understand aeolian grain surface evolution on Mars versus Earth – suggestions for ExoMars rover mission

Virtual visit by Zsuzsanna Kapui, Eötvös Lorand University ̷ Research Centre for Astronomy and Earth Sciences (Hungary) to TA2.4 Planetary Environment Facilities (PEF), AU (Denmark).
Dates of visit: 2-6 August 2021

Surface microtextures on quartz grains provide good information of the transport medium (ice, river, wind) on Earth, as shape and surface micromorphological features strongly depend on them. A well-developed system has been already used for the quartz grains, but similar detailed studies of basaltic grains have not been conducted before, although this could be relevant for Mars. We aim to develop such a system for olivine grains (main basalt forming mineral). Between 2-6 August 2021, a quartz and an olivine sand grain group (both sized 1 – 2 millimetre) were analysed by wind transport at the AWTSII Wind tunnel facility in Aarhus, Denmark.

A special, self-built box (wind tunnel section with a relatively small cross section) was designed and produced in Hungary to allow periodic transport of the sand grains from one end to the other by a motor driven rotation system. The test started with difficulty because the sands movement did not start, a combination of factors meant that even at the highest fan rotation rate of the AWTSII facility active sand transport was not achieved. Finally, the solution became that the sand holder box in the wind tunnel was also tilted by 24 degrees. The quartz and olivine sands were transported by a mixture of gravitational avalanching and wind driven transport at around 1 bar pressure. Altogether two tests were performed during around four hours to see the attrition process related to grain shapes and surface microstructures. Microscope and webcam videos as well as wind flow data (pitot tube) were collected.

Currently, microscopic analysis with Morphology instrument is underway on the returned particles. The obtained results will be included in an article in progress and in my doctoral dissertation.

Report Summary:

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