Factors affecting the electrification of wind-driven dust studied with laboratory simulations

Merrison, J.P.; Gunnlaugsson, H. P.; Hogg, M.R.; Jensen, Martin; Lykke, J.M.; Madsen, M. B.; Nielsen, M. B.; Nørnberg, P.; Ottosen, T. A.; Pedersen, R.T.; Pedersen, Søren; Sørensen, Asger

doi:10.1016/j.pss.2011.10.008

Cited by 28 publications

(21 citation statements)

References 24 publications

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“…Larger particles will sink faster to the bottom of the cloud while smaller particles remain longer at the top and can be easily transported by winds, establishing large-scale charge separation within the cloud. Similar scenarios are suggested in Merrison et al (2012); Zarka et al (2004), and in Farrell et al (1999).…”

Section: Large-scale Charge Separation Within Cloudssupporting

confidence: 76%

Ionization in Atmospheres of Brown Dwarfs and Extrasolar Planets Vi: Properties of Large-Scale Discharge Events

Bailey

Helling

Hodosán

et al. 2014

ApJ

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Mineral clouds in substellar atmospheres play a special role as a catalyst for a variety of charge processes. If clouds are charged, the surrounding environment becomes electrically activated, and ensembles of charged grains are electrically discharging (e.g. by lightning), which significantly influences the local chemistry creating conditions similar to those thought responsible for life in early planetary atmospheres. We note that such lightning discharges contribute also to the ionisation state of the atmosphere. We apply scaling laws for electrical discharge processes from laboratory measurements and numerical experiments to Drift-Phoenix model atmosphere results to model the discharge's propagation downwards (as lightning) and upwards (as sprites) through the atmospheric clouds. We evaluate the spatial extent and energetics of lightning discharges. The atmospheric volume affected (e.g. by increase of temperature or electron number) is larger in a brown dwarf atmosphere (10 8 − 10 10 m 3 ) than in a giant gas planet's (10 4 − 10 6 m 3 ). Our results suggest that the total dissipated energy in one event is < 10 12 J for all models of initial solar metallicity. First attempts to show the influence of lightning on the local gas phase indicate an increase of small carbohydrate molecules like CH and CH 2 at the expense of CO and CH 4 . Dust forming molecules are destroyed and the cloud particle properties are frozen-in unless enough time is available for complete evaporation. We summarise instruments potentially suitable to observe lightning on extrasolar objects.

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Section: Large-scale Charge Separation Within Cloudssupporting

confidence: 76%

Ionization in Atmospheres of Brown Dwarfs and Extrasolar Planets Vi: Properties of Large-Scale Discharge Events

Bailey

Helling

Hodosán

et al. 2014

ApJ

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“…It is of importance when utilizing the recirculating system that the area of the return flow is comparable (if not greater than) to that of the wind tunnel in order to minimize turbulence and irregularities in the wind stream. Fins are used to minimize rotation effects on the wind by the fan (Merrison et al 2002(Merrison et al , 2004(Merrison et al , 2007(Merrison et al , 2010(Merrison et al , 2012.…”

Section: The Aarhus Wind Tunnel Simulator (Awts) University Of Aarhumentioning

confidence: 99%

Earth as a Tool for Astrobiology—A European Perspective

et al. 2017

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Scientists use the Earth as a tool for astrobiology by analyzing planetary field analogues (i.e. terrestrial samples and field sites that resemble planetary bodies in our Solar System). In addition, they expose the selected planetary field analogues in simulation chambers to conditions that mimic the ones of planets, moons and Low Earth Orbit (LEO) space conditions, as well as the chemistry occurring in interstellar and cometary ices. This paper reviews the ways the Earth is used by astrobiologists: (i) by conducting planetary field analogue studies to investigate extant life from extreme environments, its metabolisms, adaptation strategies and modern biosignatures; (ii) by conducting planetary field analogue studies to investigate extinct life from the oldest rocks on our planet and its biosignatures; (iii) by exposing terrestrial samples to simulated space or planetary environments and producing a sample analogue to investigate changes in minerals, biosignatures and microorganisms. The European Space Agency (ESA) created a topical team in 2011 to investigate recent activities using the Earth as a tool for astrobiology and to formulate recommendations and scientific needs to improve ground-based astrobiological research. Space is an important tool for astrobiology (see Horneck et al. in Astrobiology, 16:201-243, 2016;Cottin et al., 2017), but access to space is limited. Complementing research on Earth provides fast access, more replications and higher sample throughput. The major conclusions of the topical team and suggestions for the future include more scientifically qualified calls for field campaigns with planetary analogy, and a centralized point of contact at ESA or the EU for the organization of a survey of such expeditions. An improvement of the coordinated logistics, infrastructures and funding system supporting the combination of field work with planetary simulation investigations, as well as an optimization of the scientific return and data processing, data storage and data distribution is also needed. Finally, a coordinated EU or ESA education and outreach program would improve the participation of the public in the astrobiological activities.

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“…Proposed mechanisms include the emissions of dust by processes based on thermal gradients from solar insolation, known as thermophoresis Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/pss (Wurm et al, 2008), and the electrostatic interactions that lead to low-density dust aggregates that are easily detached by modest winds Merrison et al, 2007Merrison et al, , 2011Sullivan et al, 2008). For larger grains a comparable process, yet still poorly understood, is the effect of grain electrification and the generation of electric fields upon saltation that could enhance or reduce the threshold magnitude (Holstein-Rathlou et al, 2012;Merrison, 2012;Rasmussen et al, 1996Rasmussen et al, , 2009Renno and Kok, 2008).…”

Section: Introductionmentioning

confidence: 99%

Effects of rolling on wind-induced detachment thresholds of volcanic glass on Mars

Vet

Merrison

Mittelmeijer‐Hazeleger

et al. 2014

Planetary and Space Science

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Factors affecting the electrification of wind-driven dust studied with laboratory simulations

Cited by 28 publications

References 24 publications

Ionization in Atmospheres of Brown Dwarfs and Extrasolar Planets Vi: Properties of Large-Scale Discharge Events

Ionization in Atmospheres of Brown Dwarfs and Extrasolar Planets Vi: Properties of Large-Scale Discharge Events

Earth as a Tool for Astrobiology—A European Perspective

Effects of rolling on wind-induced detachment thresholds of volcanic glass on Mars

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