Mobilization of dust on the Mars surface by the impact of small cosmic bodies

Rybakov, V. A.; Nemtchinov, I. V.; Шувалов, В. В.; Artemiev, V. I.; Medveduk, S. A.

doi:10.1029/96je03569

Cited by 16 publications

(7 citation statements)

References 26 publications

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“…On the basis of the geotherms, Wrobel et al [2006] conclude that, “It is evident that lingering temperatures at ∼30 s after the passage of the thermal pulse are high enough to produce a thermal wave extending to depths of several centimeters (temperatures above melting down to ∼15 cm) at ∼4 apparent crater diameters from impact of an ice‐rich substrate. Consequently, if given enough time, temperatures will be sufficient to melt any ice present in the upper layers of a subsurface.” The lateral extent of this heating is increased by considering the radiative effects of elevated temperatures higher in the atmosphere [ Rybakov et al , 1997]. By including these effects, significant heating can occur out to a distance of ∼10 crater diameters [ Wrobel et al , 2006].…”

Section: Discussionmentioning

confidence: 99%

Latitude dependence of Martian pedestal craters: Evidence for a sublimation‐driven formation mechanism

2009

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[1] We report on the results of a survey to document and characterize pedestal craters on Mars equatorward of $60°N and 65°S latitude. The identification of 2696 pedestal craters reveals a strong latitude dependence, with the vast majority found poleward of 33°N and 40°S. This latitudinal extent is correlated with many climate indicators consistent with the presence of an ice-rich substrate and with climate model predictions of where ice is deposited during periods of higher obliquity in the Amazonian. We have measured key physical attributes of pedestal craters, including the farthest radial extents of the pedestals, pedestal heights, and the circularity of the pedestal margins. In conjunction with the geographic distribution, our measurements strongly support a sublimation-related formation mechanism. This is in contrast to previous hypotheses, which have relied on eolian deflation to produce the elevated plateaus. The identification of marginal pits on the scarps of some pedestal craters, interpreted to be sublimation pits, provide direct evidence for the presence of ice-rich material underlying the armored surface of pedestal craters. On the basis of our findings, we propose a formation mechanism whereby projectiles impact into a volatile-rich dust/snow/ice substrate tens to hundreds of meters thick overlying a dominantly fragmental silicate regolith. The area surrounding the resulting crater becomes armored. Pedestals extend to a distance of multiple crater radii, farther than typical ejecta deposits, necessitating an armoring mechanism that is capable of indurating the surface to a distance greater than the reach of the ejecta. Return to low obliquity causes sublimation of the volatile-rich layer from the intercrater plains, lowering the elevation of the regional terrain. This yields generally circular pedestal craters elevated above the surrounding plains. As a result, the armored surfaces of pedestal craters have preserved a significant record of Amazonian climate history in the form of ice-rich deposits.

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Section: Discussionmentioning

confidence: 99%

Latitude dependence of Martian pedestal craters: Evidence for a sublimation‐driven formation mechanism

2009

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“…Their additional unpublished results were consistent with modern-day craters down to about 1 m diameter, from both stony and iron bolides, under the current atmosphere. Meanwhile, Rybakov et al (1997) and Nemtchinov et al (1998Nemtchinov et al ( , 1999a suggested that small impactors may eject large amounts of dust into the martian atmosphere and may even create local dust storm conditions.…”

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confidence: 99%

Bolides in the present and past martian atmosphere and effects on cratering processes

Попова

Nemtchinov

Hartmann

2003

Meteorit & Planetary Scien

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Bolides in the present and past martian atmosphere and effects on cratering processesAbstract-We investigate the action of the martian atmosphere on entering meteoroids for present and past atmospheres with various surface pressures to predict the smallest observable craters, and to understand the implications for the size distributions of craters on Mars and meteoroids in space. We assume different strengths appropriate to icy, stone, and iron bodies and test the results against available data on terrestrial bolides. Deceleration, ablation, and fragmentation effects are included. We find that the smallest icy, stone, and iron meteoroids to hit the martian ground at crater forming speeds of ≥500 m/s have diameters of about 2 m, 0.03-0.9 m (depending on strength), and 0.01 m, respectively, in the current atmosphere. For hypothetical denser past atmospheres, the cutoff diameters rise. At a surface pressure of 100 mb, the cutoff diameters are about 24 m, 5-12 m, and 0.14 m for the 3 classes. The weaker stony bodies in the size range of about 1-30 m may explode at altitudes of about 10-20 km above the ground.These figures imply that under the present atmosphere, the smallest craters made by these objects would be as follows: by ice bodies, craters of diameter (D) ~8 m, by stones about 0.5-6 m, and by irons, about 0.3 m. A strong depletion of craters should, thus, occur at diameters below about 0.3 m to 5 m. Predicted fragmentation and ablation effects on weak meteoroids in the present atmosphere may also produce a milder depletion below D ~500 m, relative to the lunar population. But, this effect may be difficult to detect in present data because of additional losses of small craters due to sedimentation, dunes, and other obliteration effects. Craters in strewn fields, caused by meteoroid fragmentation, will be near or below present-day resolution limits, but examples have been found.These phenomena have significant consequences. Under the present atmosphere, the smallest (decimeter-scale) craters in sands and soils could be quickly obliterated but might still be preserved on rock surfaces, as noted by Hörz et al. (1999). Ancient crater populations, if preserved, could yield diagnostic signatures of earlier atmospheric conditions. Surfaces formed under past denser atmospheres (few hundred mbar), if preserved by burial and later exposed by exhumation, could show: a) striking depletions of small craters (few meter sizes up to as much as 200 m), relative to modern surfaces; b) more clustered craters due to atmospheric breakup; and c) different distributions of meteorite types, with 4 m to 200 m craters formed primarily by irons instead of by stones as on present-day Mars. Megaregolith gardening of the early crust would be significant but coarser than the gardening of the ancient lunar uplands.

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“…This, in turn, results in vapor that rapidly travels downward around the lip of the cavity, into atmosphere of much lower pressure (ambient), and "attaches" to the surface (due to the continual feeding of vapor to this region as the cloud expands). This same phenomenon has been observed computationally (e.g., Crawford et al 1995;Rybakov et al 1997;Sugita and Schultz 2002) and in laboratory experiments from high-speed imaging of impactgenerated vaporization (Schultz 1996). The pressure in the blast front equilibrates to ambient atmospheric values once it reaches ~25 km from the explosion, which occurs at ~50 s (X velocity = 0).…”

Section: Results: Impact Model Pressure/blast Wavementioning

confidence: 56%

“…Estimates using Equation 5 yield a radiation flux of ~10 kW/cm 2 or greater for the first ten seconds after impact (extending to distances of ~0.5 apparent crater diameter). Surfaces subjected to such heat will reach the evaporation limit, initiating vaporization of any present water-ice (Rybakov et al 1997). The flux of radiation decreases to ~0.7 kW/cm 2 at later times and greater distances from impact (e.g., ~4 apparent crater diameters at ~30 s).…”

Section: Thermal Responsementioning

confidence: 99%

An atmospheric blast/thermal model for the formation of high‐latitude pedestal craters

Wrobel

Schultz

Crawford

2006

Meteorit & Planetary Scien

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Abstract-Although tenuous, the atmosphere of Mars affects the evolution of impact-generated vapor. Early-time vapor from a vertical impact expands symmetrically, directly transferring a small percentage of the initial kinetic energy of impact to the atmosphere. This energy, in turn, induces a hemispherical shock wave that propagates outward as an intense airblast (due to high-speed expansion of vapor) followed by a thermal pulse of extreme atmospheric temperatures (from thermal energy of expansion). This study models the atmospheric response to such early-time energy coupling using the CTH hydrocode written at Sandia National Laboratories. Results show that the surface surrounding a 10 km diameter crater (6 km "apparent" diameter) on Mars will be subjected to intense winds (~200 m/s) and extreme atmospheric temperatures. These elevated temperatures are sufficient to melt subsurface volatiles at a depth of several centimeters for an ice-rich substrate. Ensuing surface signatures extend to distal locations (~4 apparent crater diameters for a case of 0.1% energy coupling) and include striations, thermally armored surfaces, and/or ejecta pedestals-all of which are exhibited surrounding the freshest high-latitude craters on Mars. The combined effects of the atmospheric blast and thermal pulse, resulting in the generation of a crater-centered erosion-resistant armored surface, thus provide a new, very plausible formation model for high-latitude Martian pedestal craters.

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Mobilization of dust on the Mars surface by the impact of small cosmic bodies

Cited by 16 publications

References 26 publications

Latitude dependence of Martian pedestal craters: Evidence for a sublimation‐driven formation mechanism

Latitude dependence of Martian pedestal craters: Evidence for a sublimation‐driven formation mechanism

Bolides in the present and past martian atmosphere and effects on cratering processes

An atmospheric blast/thermal model for the formation of high‐latitude pedestal craters

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