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Wind driven dust resuspension is actively and ubiquitously observed at the surface of Mars, however the mechanisms involved, and conditions required are poorly understood (Neakrase et al., 2016). The objective of this laboratory study is to investigate various dust resuspension mechanisms using a unique set of recirculating environmental wind tunnel facilities at Aarhus University (Holstein-Rathlou et al., 2014). This study employs various sensor techniques including digital microscopy and optical reflectance to quantify dust removal as well as Laser Doppler Velocimetry and optical opacity measurement for determining dust concentration (Jakobsen et al., 2019). Importantly in these studies the dust was deposited from suspension within an environmental wind tunnel (Merrison et al., 2008).Already from preliminary experiments significant advancements in our knowledge of dust resuspension have been made. Specifically, for the first time under Martian conditions direct wind driven dust remobilization has been observed (Rondeau et al., 2015). As expected, the process involved dust aggregate detachment and transport. Also for the first time saltation induced dust resuspension has been recreated (i.e. impact induced dust resuspension) from a loose sand bed coated with dust. Interestingly preliminary estimates have shown that both of these mechanisms appear to have similar values of threshold shear stress of around 0.07Pa, this is close to the expected threshold for saltation (Andreotti et al., 2021). It is hoped that both the resuspension flux and threshold can be quantified.These studies are part of an international EU supported research project called ROADMAP (https://roadmap.aeronomie.be/). Three Mars analogue dust prototypes ‘are being used in these experiments. These have been developed and characterized by the ROADMAP team.AcknowledgmentsThis project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101004052.ReferencesAndreotti, B., Claudin, P., Iversen, J. J., Merrison, J. P., and Rasmussen, K. R.: A lower-than-expected saltation threshold at Martian pressure and below, Proceedings of the National Academy of Sciences, 118, 2021.Holstein-Rathlou, C., Merrison, J., Iversen, J., Jakobsen, A., Nicolajsen, R., Nørnberg, P., Rasmussen, K., Merlone, A., Lopardo, G., and Hudson, T.: An environmental wind tunnel facility for testing meteorological sensor systems, Journal of atmospheric and oceanic technology, 31, 447-457, 2014.Jakobsen, A. B., Merrison, J., and Iversen, J. J.: Laboratory study of aerosol settling velocities using laser Doppler velocimetry, Journal of Aerosol Science, 135, 58-71, 2019.Merrison, J. P., Bechtold, H., Gunnlaugsson, H., Jensen, A., Kinch, K., Nornberg, P., and Rasmussen, K.: An environmental simulation wind tunnel for studying Aeolian transport on mars, Planetary and Space Science, 56, 426-437, 2008.Neakrase, L., Balme, M., Esposito, F., Kelling, T., Klose, M., Kok, J., Marticorena, B., Merrison, J., Patel, M., and Wurm, G.: Particle lifting processes in dust devils, Space Science Reviews, 203, 347-376, 2016.Rondeau, A., Merrison, J., Iversen, J. J., Peillon, S., Sabroux, J.-C., Lemaitre, P., Gensdarmes, F., and Chassefière, E.: First experimental results of particle re-suspension in a low pressure wind tunnel applied to the issue of dust in fusion reactors, Fusion Engineering and Design, 98, 2210-2213, 2015. |
