Radiative cooling within illuminated layers of dust on (pre)-planetary surfaces and its effect on dust ejection

Kocifaj, Miroslav; Klačka, J.; Kelling, T.; Wurm, Gerhard

doi:10.1016/j.icarus.2010.10.006

Cited by 18 publications

(27 citation statements)

References 17 publications

(30 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As thermal radiation cannot escape because ice is opaque at this wavelength, the ice heats up below and is cooler at the surface (greenhouse effect). The same can occur for dust samples as visible light enters through the pores or forward scattering and thermal radiation cannot leave the same way 17,24 . In this study, this is a minute detail, as it influences only the top dust layer of about 100 µm and does not change the coarser temperature structure of the sample.…”

Section: Methodsmentioning

confidence: 87%

“…The capability of gas flowing through heated or insolated dust layers can also lead to a significant pressure increase. It can even be sufficient to levitate large dust aggregates or to eruptively eject particles from the surface, which has been shown in ground-based laboratory experiments 10,[14][15][16][17] . To evaluate the gas mass flow in the drop tower experiments we use equation (1), with p avg = 4 mbar and T avg = 300 K. For a length of l = 2 cm (depth of the dust bed) and basaltic powder with a thermal conductivity of 0.01 W K −1 m −1 (ref.…”

mentioning

confidence: 90%

See 1 more Smart Citation

The martian soil as a planetary gas pump

et al. 2013

View full text Add to dashboard Cite

Mars has an active surface, with omnipresent small dust particles and larger debris. With an ambient pressure below 10 mbar, which is less than 1% of the surface pressure on Earth, its CO 2 atmosphere is rather tenuous. Aeolian processes on the surface such as drifting dunes, dust storms and dust devils are nevertheless still active [1][2][3] . The transport of volatiles below the surface, that is, through the porous soil, is unseen but needs to be known for balancing mass flows 4,5 . Here, we describe a mechanism of forced convection within porous soils. At an average ambient gas pressure of 6 mbar, gas flow through the porous ground of Mars by thermal creep is possible and the soil acts as a (Knudsen) pump. Temperature gradients provided by local and temporal variations in solar insolation lead to systematic gas flows. Our measurements show that the flow rates can outnumber diffusion rates. Mars is the only body in the Solar System on which this can occur naturally. Our laboratory experiments reveal that the surface of Mars is efficient in cycling gas through layers at least centimetres above and below the soil with a turnover time of only seconds to minutes.As a terrestrial planet, Mars shares many geological and physical processes with Earth 6

show abstract

Section: Methodsmentioning

confidence: 87%

mentioning

confidence: 90%

The martian soil as a planetary gas pump

et al. 2013

View full text Add to dashboard Cite

show abstract

“…We do not aim to construct a detailed model at this point but just quantify the ratio Figure 1: Sketch of the influence of a shadowed region. A detailed calculation is done in Kocifaj et al (2011). For the illuminated dust bed the temperature gradient induced thermal creep pumps gas from the deeper layers upwards.…”

Section: Illumination and Liftingmentioning

confidence: 99%

Amplification of dust loading in Martian dust devils by self-shadowing

Kuepper

Wurm

2016

Icarus

Self Cite

View full text Add to dashboard Cite

Insolation of the Martian soil leads to a sub-surface overpressure due to thermal creep gas flow. This could support particle entrainment into the atmosphere. Short time shadowing e.g. by the traverse of a larger dust devil would enhance this effect. We find in microgravity experiments that mass ejection rates are increased by a factor of 10 for several seconds if a light source of 12.6 kW/m 2 is turned off. Scaled to Mars this implies that self-shadowing of a partially opaque dust devil might lead to a strongly amplified flux of lifted material. We therefore suggest that self-shadowing might be a mechanism on Mars to increase the total dust loading of a dust devil and keep it self-sustained.

show abstract

“…In recent years a number of papers showed that at low‐pressure (hPa) particles can be ejected from a dust sample by mere illumination with visible radiation [ Wurm and Krauss , ; Kocifaj et al , ; Kelling et al , ; de Beule et al , ]. This mechanism works independently of any wind if the illumination is strong enough.…”

Section: Introductionmentioning

confidence: 99%

“…A typical temperature profile of an illuminated dust bed is sketched in Figure . Absolute values depend on the insolation light flux, but calculated temperature profiles always show a similar structure [ Kocifaj et al , ].…”

Section: Introductionmentioning

confidence: 99%

Thermal creep-assisted dust lifting on Mars: Wind tunnel experiments for the entrainment threshold velocity

Küpper

Wurm

2015

J. Geophys. Res. Planets

View full text Add to dashboard Cite

In this work we present laboratory measurements on the reduction of the threshold friction velocity necessary for lifting dust if the dust bed is illuminated. Insolation of a porous soil establishes a temperature gradient. At low ambient pressure this gradient leads to thermal creep gas flow within the soil. This flow leads to a subsurface overpressure which supports lift imposed by wind. The wind tunnel was run with Mojave Mars Simulant and air at 3, 6, and 9mbar, to cover most of the pressure range at Martian surface levels. Our first measurements imply that the insolation of the Martian surface can reduce the entrainment threshold velocity between 4% and 19% for the conditions sampled with our experiments. An insolation activated soil might therefore provide additional support for aeolian particle transport at low wind speeds.

show abstract

Radiative cooling within illuminated layers of dust on (pre)-planetary surfaces and its effect on dust ejection

Cited by 18 publications

References 17 publications

The martian soil as a planetary gas pump

The martian soil as a planetary gas pump

Amplification of dust loading in Martian dust devils by self-shadowing

Thermal creep-assisted dust lifting on Mars: Wind tunnel experiments for the entrainment threshold velocity

Contact Info

Product

Resources

About