Releasing Atmospheric Martian Dust in Sand Grain Impacts

Becker, Tim; Teiser, Jens; Jardiel, Teresa; Peiteado, M.; Muñoz, Olga; Martikainen, Julia; Martı́n, Juan Carlos Gómez; Wurm, Gerhard

doi:10.3847/psj/ac8477

Cited by 5 publications

(6 citation statements)

References 56 publications

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“…Our previous study analyzed this process for individual impacts-i.e., that bonds are broken down to the (sub-) micrometer scale, as we could detect particles even below 1 μm in diameter being ejected from slow saltating impacts (Becker et al 2022). In that study, the final estimate of how much dust per saltating impact could go into long-term suspension in the atmosphere assumed a cutoff diameter of 3 μm as the upper limit.…”

Section: Introductionmentioning

confidence: 89%

“…Second, we caught sedimenting particles and analyzed their shape under an optical microscope and used a scanning electron microscope (SEM) for high-resolution images. To obtain the aspired data, we used an extended version of the setup from our previous work (Becker et al 2022).…”

Section: Methodsmentioning

confidence: 99%

“…For the experiment, we reused the Martian Global Simulant (MGS) sample (Cannon et al 2019) we used in our previous work (Becker et al 2022) as well. That is, we produced a bimodal size distribution of fine clay-sized particles and larger sand-sized saltators.…”

Section: Soil: Martian Simulantmentioning

confidence: 99%

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Ejected Particles after Impact Splash on Mars: Aggregates and Aerodynamics

Becker,

Teiser,

Jardiel

et al. 2023

Planet. Sci. J.

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Our earlier laboratory measurements showed that low-velocity sand impacts release fine <5 μm dust from a Martian simulant soil. This dust will become airborne in the Martian atmosphere. Here, we extend this study by measuring aerodynamic properties of ejecta and characterizing deviations from the behavior of spherical, monolithic grains. We observe the settling of particles emitted as part of an impact splash. The sizes (20 to 280 μm) and sedimentation velocities (0.1 to 0.8 m s−1) of the particles are deduced from high-speed videos while the particles sediment under low ambient pressure of about 1 mbar. The particles regularly settle slower than expected, down to a factor of about 0.3. Using optical microscopy, the shape of the captured particles is characterized by simple axis ratios (longest/smallest), which show that the vast majority of particles are irregular but typically not too elongated, with axis ratios below 2 on average. Electron microscopy further reveals that the particles are typically porous aggregates, which is the most likely reason for the reduction of the sedimentation velocity. Due to the reduced bulk density, aggregates up to 10 μm in diameter should regularly be a part of the dust in the Martian atmosphere.

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Section: Introductionmentioning

confidence: 89%

Section: Methodsmentioning

confidence: 99%

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Ejected Particles after Impact Splash on Mars: Aggregates and Aerodynamics

Becker,

Teiser,

Jardiel

et al. 2023

Planet. Sci. J.

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“…Much of the surface of Mars is covered by dust and sand, and ways to mobilize these grains are important for many studies. The scientific problems range from the entrainment of dust into the atmosphere by wind and saltation, dust devils, or electrostatics (Greeley et al 1980;Cantor et al 1999;Montabone et al 2005;Kok & Renno 2008;Kok et al 2012;Reiss & Lorenz 2016;Becker et al 2022;Lorenz 2023;Toledo et al 2023) to the formation of geomorphologic features like dunes (Chojnacki et al 2011;Bridges et al 2012aBridges et al , 2012bKok et al 2012). Quite generally, mobilization is important for all kinds of slopes on Mars because their angle is set by downhill motion.…”

Section: Introductionmentioning

confidence: 99%

Dry Downhill Particle Motion on Mars

Bila,

Wurm,

Stuers

et al. 2024

Planet. Sci. J.

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We recently flew a new setup on parabolic flights for the first time to study particle motion on Martian slopes under Martian gravity. Here, we describe the initial experiments. We used dust/sand beds at varying ambient pressure of a few hundred pascals. The inclination of the particle bed was varied from 0° to 45° and parts of the surface were illuminated under varying conditions. We could observe downhill motion of material related to the insolation at the lowest light flux used of 591 ± 11 W m−2 for JSC Martian simulant. Motion occurred at significantly lower inclinations under illumination than without illumination, i.e., down to about 10° compared to about 20°–30°, respectively. We attribute this reduction in slope to thermal creep gas flow in the subsoil. This induces a Knudsen compressor, which supports grains against gravity and leads to smaller angles of repose. This is applicable to recurring slope lineae and slopes on Mars in general.

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“…This may not be taken for granted as micrometer grains are rather adhesive. Nevertheless, Becker et al [5] recently showed in detail that the release of particles even smaller than 1 µm from a dust bed is already possible in rather moderate collisions. The solid impactors were of the order from 100 to 200 µm and had impact speeds of only about 1 m/s.…”

Section: Introductionmentioning

confidence: 99%

Charged Atmospheric Aerosols from Charged Saltating Dust Aggregates

et al. 2023

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Grain collisions in aeolian events, e.g., due to saltation, result in atmospheric aerosols. They may regularly be electrically charged, but individual charge balances in collisions including small grains are not easily obtained on the ground. We therefore approach this problem in terms of microgravity, which allows for the observation of collisions and the determination of small charges. In a drop tower experiment, ∼1 mm dust aggregates are traced before and after a collision within the electric field of a plate capacitor. The sum of the electric charge of two particles (total charge) before and after the collision often strongly deviates from charge conservation. Due to the average low collision velocities of 0.2 m/s, there is no large scale fragmentation. However, we do observe small charged particles emerging from collisions. The smallest of these particles are as small as the current resolution limit of the optical system, i.e., they are at least as small as tens of µm. In the given setting, these small fragments may carry 1 nC/m2–1 µC/m2 which is between 1% and ten times the surface charge density of the large aggregates. These first experiments indicate that collisions of charged aggregates regularly shed charged grains into the atmosphere, likely down to the suspendable aerosol size.

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Releasing Atmospheric Martian Dust in Sand Grain Impacts

Cited by 5 publications

References 56 publications

Ejected Particles after Impact Splash on Mars: Aggregates and Aerodynamics

Ejected Particles after Impact Splash on Mars: Aggregates and Aerodynamics

Dry Downhill Particle Motion on Mars

Charged Atmospheric Aerosols from Charged Saltating Dust Aggregates

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