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Evolution of the surfaces of cometary nuclei is determined by the sublimation of ice. The rate of sublimation is commonly calculated using the simple Hertz–Knudsen formula, which should be corrected by a temperature dependent sublimation coefficient αs (Kossacki et al., 1999; Gundlach et al., 2011; Kossacki and Leliwa–Kopystynski, 2014). In this work influence of C3H6O (acetone), and CH3OH (methanol)...
This work is intended to answer the question, whether on comet 67P/Churyumov–Gerasimenko pristine, not hardened material can be locally preserved close to the surface. Simulated is the thermally driven sintering of ice-dust grains underlying the dust mantle. Considered is the Ma׳at region located at the north side of the small lobe Head. It is shown that locally thermal conditions can allow preservation...
From the operation of the MUPUS thermal probe Spohn et al. (2015) concluded that the material of the nucleus of 67P/Churyumov–Gerasimenko is likely to have a high strength, at least locally at the Philae landing site. In this work we consider the derived strength of the material in order to constrain its granulation. For this purpose we performed numerical simulations of the long-term sintering of...
Emission of volatiles for the long-period Comet C/2006 W3 Christensen was observed before perihelion from 3.7AU through perihelion passage at 3.13AU till 5.0AU after perihelion. Coma is found to be strongly enriched in molecules more volatile than water. At heliocentric distances 3.13–3.7AU activity of the comet was mostly driven by CO emission (Bockelée-Morvan, D., et al. [2010]. Astron. Astrophys...
Comet 9P/Tempel 1 was imaged during two consecutive perihelion passages. According to Thomas et al. (Thomas, et al. [2013]. Icarus 222, 453–466) one scarp located at 40°S receded up to 50m. I attempted to use this observation to constrain local material properties of the nucleus. For this purpose I simulated recession of a model scarp due to sub-dust sublimation of ice. I have found, that the observed...
The sublimation rate of ice is commonly calculated using the simple Hertz–Knudsen formula. This formula is derived from the kinetic theory of gases and ignores microphysical processes determining the actual sublimation rate. The microphysical processes can be accounted for by including the temperature dependent sublimation coefficient (Kossacki, K.J., et al. [1999]. Planet. Space Sci. 47, 1521–1530;...
RSLs are narrow, dark albedo features on relatively steep slopes that appear during warm seasons and fade in the cold ones. So far they have only been observed in mid-latitudes where surface temperature is too high, periodically exceeding 300K, for the presence of shallow ground ice. We attempt to determine what conditions are needed for the liquescence of salt to occur exactly when the RSLs are observed...
Comet 29P/Schwassmann–Wachmann 1 is a continually active object moving along nearly circular orbit at a large heliocentric distance ∼6AU. The comet is famous for its repeated outbursts. We look for structure and composition of the nucleus that leads to the observed frequent outbursts. We performed series of numerical simulations dealing with evolution of the nucleus, including changes of the structure...
The sublimation rate of ice is commonly calculated using simple Hertz–Knudsen formula. This formula is derived from the kinetic theory of gases and ignores microphysical processes determining the actual sublimation rate. The microphysical processes can be accounted for by including in the Herz–Knudsen equation a temperature dependent sublimation coefficient (Kossacki, K.J., Markiewicz, W.J., Skorov,...
Titan is the only body, beside the Earth, where liquid is present on the surface. This paper is aimed to show the properties of possible convection in a porous regolith on Titan. In our previous work (Czechowski, L., Kossacki, K.J. [2009]. Icarus 202, 599–607) we showed, that the Rayleigh number Ra can exceed its critical value Ra c . Hence, the convective motion of liquid filling pores in...
In this work we investigated changes of the water emission from a model comet of the size and orbital elements of Comet P/2008 R1 (Garradd). We performed simulations for model cometary nuclei of different compositions and two different orientations in space. Our simulations indicate, that the emission of water decreases from one orbital period to another one, but in some cases slowly. When the rotation...
This work is a continuation of our previous paper about brightening of Comet 17P/Holmes (Kossacki, K.J., Szutowicz, S. [2010]. Icarus 207, 320–340). In that paper we presented results of simulations indicating that the nonuniform crystallization of amorphous water ice itself is probably not sufficient for an explosion. In the present work we investigate the possibility that the explosion is caused...
Recent observations of the surface of Mars have shown several fresh mid-latitude craters. Some of these craters show exposed ice (Byrne, S. et al. [2009]. Science 325, 1674–1676.). In some craters, albedo of ice slowly decreases, while in others, it remains nearly constant. We attempt to determine influence of the regolith structure on the rate of sublimation of ice. For this purpose we performed...
Gullies are among the most intriguing structures identified on the surface of Mars. Most common are gullies located on the slopes of craters which are probably formed by liquid water transported by shallow aquifers (Heldmann, J.L., Carlsson, E., Johansson, H., Mellon, M.T., Toon, O.B. [2007]. Icarus 188, 324–344). Two particular types of gullies are found on slopes of isolated hills and dunes. The...
Our work was inspired by the recent brightening of Comet 17P/Holmes. The recently observed increase in brightness of this comet was correlated with emission of dust, probably larger in mass than the dust mantle of the nucleus. We analyzed the hypothesis that the comet can eject a large mass of dust due to non-uniform crystallization of amorphous water ice. For this purpose, we simulated the evolution...
In this paper we intend to analyze how the sublimation of ice from cometary nuclei affects changes of the moments of inertia. Our aim is to show general trends for different orientations of cometary nucleus’ rotation axis. Thus we apply numerical model of a hypothetical homogeneous and initially spherical nucleus composed of water ice and dust. As an example we present simulations for a model comet...
In this paper we attempt to answer the question, how formation of a small-scale trench in the martian regolith affects local distribution of the subsurface ice. We are especially interested in the consequences of digging a trench to search for buried ice, as has been done during the Phoenix Mars Lander mission. However, the results may be also applicable for natural troughs, or cracks. We present...
In the current work we analyze properties of the dust mantle, its thickness and thermal conductivity, necessary to reproduce observed rate of water production of Comet 9P/Tempel 1. For this purpose we considered simplified shape of the comet nucleus approximated by the symmetric prolate ellipsoid with smooth surface. We have performed simulations, using models with dust mantle of the thickness either...
This work is intended to investigate the influence of temperature-dependent metamorphism of ice on the shape of small depressions in the surface of cometary nuclei. We are mainly interested in the role of initial cohesivity of a nucleus. For this purpose we simulate sublimation of ice from the facets of initially cylindrical depressions in ice of different initial structure. The simulations account...
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