Injection of dust into the martian atmosphere: Evidence from the viking gas exchange experiment |
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| Affiliation: | 1. Remote Sensing Center and Department Geology/Geography, University of Massachusetts, Amherst, Massachusetts 01003, USA;2. Applied Analysis Incorporated, Groton, Massachusetts 01450, USA;1. Department of Civil and Geomatics Engineering, Tafresh University, 39518-79611 Tafresh, Iran;2. Department of Surveying and Geomatics Engineering, Center of Excellence in Geomatics Engineering and Disaster Prevention, College of Engineering, University of Tehran, P.O. Box 11155-4563, Tehran, Iran;3. Department of Physics, Tafresh University, 39518-79611 Tafresh, Iran;1. Science and Technology on Aerospace Flight Dynamics Laboratory, Beijing Aerospace Control Center, Beijing, China;2. Institute of Applied Mathematics, Morningside Center of Mathematics and LESC, Institute of Computational Mathematics, Academy of Mathematics and System Science, Chinese Academy of Sciences, Beijing, China;3. Department of Aerospace Guidance Navigation and Control, School of Astronautics, Beihang University, Beijing, China;4. Beijing Institute of Aerospace Control Devices, Beijing, China;5. National Astronomical Observatories, Chinese Academy of Sciences, Beijing, China;6. University of Chinese Academy of Sciences, Beijing, China;1. Department of Physics, University of Oxford, OX1 3RH, UK;2. National Astronomical Observatories, Chinese Academy of Sciences, Beijing, China;3. Department of Astrophysics/IMAPP, Radboud University, Nijmegen, P.O. Box 9010, 6500 GL Nijmegen, The Netherlands;4. Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven, The Netherlands;5. Astrophysical Institute, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium;6. Kapteyn Astronomical Institute, University of Groningen, PO Box 800, NL-9700 AV Groningen, The Netherlands;7. ASTRON, Oude Hoogeveensedijk 4, 7991 PD Dwingeloo, The Netherlands;1. European Commission, Joint Research Centre, Institute for Reference Materials and Measurements, Retieseweg 111, B-2440 Geel, Belgium;2. Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia |
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| Abstract: | It is proposed that dust storms on Mars that develop during predawn hours may be triggered by a freeze/thaw dust injection process. The model is based on a phenomenon that was observed during the Viking Gas Exchange experiments on Mars, in which adsorbed gas was catastrophically desorbed from soil samples when exposed to humidification at ∼5°C. Similar conditions may develop at midlatitude locations on Mars near perihelion, and a similar humidification-driven desorption process might occur in the soil column. If soils are dampened during humikification, desorbed gases in confined pore spaces could possibly reach 8.6 bar. Diurnal freezing may possibly cause H2O to crystallize within the pores, possibly producing cohesive soil failure, release of the trapped gas, and explosive injection of freeze-dried powdery overburden dust into the atmospheric column. The process could potentially occur at 5–20 cm depth, and the freeze/thaw dust injection event may initiate after 10:00 PM local time (20°S lat). Dust would be injected at velocities approaching 450 m sec−1 and it would remain in the atmosphere for several hours before settling out. The plumes could potentially regenerate diurnally until the growing atmospheric dust load produced sufficient dampening of the diurnal thermal wave to prevent freeze/thaw. Seasonal replenishment of H2O could potentially occur by upward migration from depth during the period between 150 and 475 sols after perihelion. The model was experimentally tested and the results were in good agreement with predictions, although a factor of 14 times more gas evolved from the laboratory samples than from the Viking samples. Most of the characteristics of the predawn storms could possibly be adequately explained by the freeze/thaw injection model, including (1) predawn onsets, (2) postperihelion seasonal occurence, (3) daily recurrence during the initial phases of the storms, and (4) generation of blue clouds (H2O ice) at the storm sites. The process may possibly occur over widespread locations at midlatitudes during seasonal retreat of “tempofrost” from these latitude belts. Permanent low albedo features in these latitude belts may possibly be regions of preferential humidification-induced dust entrainment and net dust removal. The H2O injected into the atmosphere may potentially be a major source of H2SO4 and HCl aerosols, which may possibly chemically react with the regolith to form soluble sulfate and chloride salts. Mg2+ may be preferentially depleted from the dust. |
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