Laboratory Investigation of the Evolution of Cometary Analogs: Results and Interpretation

Kossacki, Konrad J.; Kömle, Norbert I.; Leliwa-Kopystyński, J.; Kargl, Günter

doi:10.1006/icar.1997.5701

Cited by 47 publications

(32 citation statements)

References 20 publications

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“…Such a depth variation would not be surprising in view of both laboratory simulations (e.g. Gruen et al 1991Gruen et al ,1993Kossacki et al 1997) and theoretical modeling (e.g. Prialnik & Mekler 1991;Espinasse et al 1991;Steiner & Komle 1993;Benkhoff & Huebner 1995), which suggest that layers develop due to sublimation of and recondensation of ices.…”

Section: Discussionmentioning

confidence: 96%

MIRO observations of subsurface temperatures of the nucleus of 67P/Churyumov-Gerasimenko

Schloerb

Keihm

Allmen

et al. 2015

A&A

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Observations of the nucleus of 67P/Churyumov-Gerasimenko in the millimeter-wave continuum have been obtained by the Microwave Instrument for the Rosetta Orbiter (MIRO). We present data obtained at wavelengths of 0.5 mm and 1.6 mm during September 2014 when the nucleus was at heliocentric distances between 3.45 and 3.27 AU. The data are fit to simple models of the nucleus thermal emission in order to characterize the observed behavior and make quantitative estimates of important physical parameters, including thermal inertia and absorption properties at the MIRO wavelengths. MIRO brightness temperatures on the irregular surface of 67P are strongly affected by the local solar illumination conditions, and there is a strong latitudinal dependence of the mean brightness temperature as a result of the seasonal orientation of the comet's rotation axis with respect to the Sun. The MIRO emission exhibits strong diurnal variations, which indicate that it arises from within the thermally varying layer in the upper centimeters of the surface. The data are quantitatively consistent with very low thermal inertia values, between 10-30 J K −1 m −2 s − 1 2 , with the 0.5 mm emission arising from 1 cm beneath the surface and the 1.6 mm emission from a depth of 4 cm. Although the data are generally consistent with simple, homogeneous models, it is difficult to match all of its features, suggesting that there may be some vertical structure within the upper few centimeters of the surface. The MIRO brightness temperatures at high northern latitudes are consistent with sublimation of ice playing an important role in setting the temperatures of these regions where, based on observations of gas and dust production, ice is known to be sublimating.

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Section: Discussionmentioning

confidence: 96%

MIRO observations of subsurface temperatures of the nucleus of 67P/Churyumov-Gerasimenko

Schloerb

Keihm

Allmen

et al. 2015

A&A

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“…They observed that in addition to the hard icy layer formed by sintering or recondensation of ice, a cohesive ice-free crust had been formed by the paraffin, which acted as a glue between mineral grains. The results of Kossacki et al (1997) showed that the thickness of the hard ice layer below the surface can reach the entire thickness of the sample holder, 8 cm in that case, after a few tens of hours of insolation. Depending on the exact physical process at work in the metamorphism of the ice layer, it might show a higher bulk density than the initial highly porous material.…”

Section: Insights From Laboratory Experimentsmentioning

confidence: 94%

“…However, if the evolution of the material results in a spatial segregation of the dust and the ice, the albedo will increase significantly. Kömle et al (1996) and Kossacki et al (1997) have conducted experiments at the Institut für Weltraumforschung (IWF) of Graz to complement previous KOSI studies, largely reusing similar protocols and materials. Kömle et al (1996) introduced paraffin in the ice-dust mixture to simulate the organic component inferred at the surface of comets.…”

Section: Insights From Laboratory Experimentsmentioning

confidence: 99%

OSIRIS observations of meter-sized exposures of H₂O ice at the surface of 67P/Churyumov-Gerasimenko and interpretation using laboratory experiments

Pommerol

Thomas

El‐Maarry

et al. 2015

A&A

108

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Since OSIRIS started acquiring high-resolution observations of the surface of the nucleus of comet 67P/Churyumov-Gerasimenko, over one hundred meter-sized bright spots have been identified in numerous types of geomorphologic regions, but mostly located in areas receiving low insolation. The bright spots are either clustered, in debris fields close to decameter-high cliffs, or isolated without structural relation to the surrounding terrain. They can be up to ten times brighter than the average surface of the comet at visible wavelengths and display a significantly bluer spectrum. They do not exhibit significant changes over a period of a few weeks. All these observations are consistent with exposure of water ice at the surface of boulders produced by dislocation of the weakly consolidated layers that cover large areas of the nucleus. Laboratory experiments show that under simulated comet surface conditions, analog samples acquire a vertical stratification with an uppermost porous mantle of refractory dust overlaying a layer of hard ice formed by recondensation or sintering under the insulating dust mantle. The evolution of the visible spectrophotometric properties of samples during sublimation is consistent with the contrasts of brightness and color seen at the surface of the nucleus. Clustered bright spots are formed by the collapse of overhangs that is triggered by mass wasting of deeper layers. Isolated spots might be the result of the emission of boulders at low velocity that are redepositioned in other regions.

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“…Arakawa et al (2000) performed impact experiments on porous mixtures of H 2 O ice-CO 2 ice-pyrophylite. These targets had thermally stratified structure due to illumination of the sample by the solar-simulating energy flux: The sublimation processes modify the medium and form the stratified structure because the initially uniform sample loses the volatiles (H 2 O ice and CO 2 ice), and the sublimation of any particular ice depends on depth (Kossacki et al 1997). They found that the resultant crater size was less sensitive to the impact energy compared to that on crystalline ice target.…”

Section: Introductionmentioning

confidence: 92%

Impact Experiments on Porous Icy-Silicate Cylindrical Blocks and the Implication for Disruption and Accumulation of Small Icy Bodies

Arakawa

Leliwa-Kopystyński

Maeno

2002

Icarus

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Laboratory Investigation of the Evolution of Cometary Analogs: Results and Interpretation

Cited by 47 publications

References 20 publications

MIRO observations of subsurface temperatures of the nucleus of 67P/Churyumov-Gerasimenko

MIRO observations of subsurface temperatures of the nucleus of 67P/Churyumov-Gerasimenko

OSIRIS observations of meter-sized exposures of H₂O ice at the surface of 67P/Churyumov-Gerasimenko and interpretation using laboratory experiments

Impact Experiments on Porous Icy-Silicate Cylindrical Blocks and the Implication for Disruption and Accumulation of Small Icy Bodies

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Laboratory Investigation of the Evolution of Cometary Analogs: Results and Interpretation

Cited by 47 publications

References 20 publications

MIRO observations of subsurface temperatures of the nucleus of 67P/Churyumov-Gerasimenko

MIRO observations of subsurface temperatures of the nucleus of 67P/Churyumov-Gerasimenko

OSIRIS observations of meter-sized exposures of H2O ice at the surface of 67P/Churyumov-Gerasimenko and interpretation using laboratory experiments

Impact Experiments on Porous Icy-Silicate Cylindrical Blocks and the Implication for Disruption and Accumulation of Small Icy Bodies

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Product

Resources

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OSIRIS observations of meter-sized exposures of H₂O ice at the surface of 67P/Churyumov-Gerasimenko and interpretation using laboratory experiments