Please use this identifier to cite or link to this item: http://hdl.handle.net/1893/27771
Appears in Collections:Biological and Environmental Sciences Journal Articles
Peer Review Status: Refereed
Title: Thermal fracturing on comets: Applications to 67P/Churyumov-Gerasimenko
Author(s): Attree, Nicholas
Groussin, Olivier
Jorda, Laurent
Rodionov, Sergey
Auger, Anne-Therese
Thomas, Nicolas
Brouet, Yann
Poch, Olivier
Kührt, Ekkehard
Knapmeyer, Martin
Preusker, Frank
Scholten, Frank
Knollenberg, Jörg
Hviid, Stubbe
Hartogh, Paul
Keywords: comets: general
comets: individual: 67P
Churyumov-Gerasimenko
planets and satellites: physical evolution
Issue Date: 28-Feb-2018
Date Deposited: 10-Sep-2018
Citation: Attree N, Groussin O, Jorda L, Rodionov S, Auger A, Thomas N, Brouet Y, Poch O, Kührt E, Knapmeyer M, Preusker F, Scholten F, Knollenberg J, Hviid S & Hartogh P (2018) Thermal fracturing on comets: Applications to 67P/Churyumov-Gerasimenko. Astronomy and Astrophysics, 610, Art. No.: A76. https://doi.org/10.1051/0004-6361/201731937
Abstract: We simulate the stresses induced by temperature changes in a putative hard layer near the surface of comet 67P/Churyumov-Gerasimenko with a thermo-viscoelastic model. Such a layer could be formed by the recondensation or sintering of water ice (and dust grains), as suggested by laboratory experiments and computer simulations, and would explain the high compressive strength encountered by experiments on board the Philae lander. Changes in temperature from seasonal insolation variation penetrate into the comet’s surface to depths controlled by the thermal inertia, causing the material to expand and contract. Modelling this with a Maxwellian viscoelastic response on a spherical nucleus, we show that a hard, icy layer with similar properties to Martian permafrost will experience high stresses: up to tens of MPa, which exceed its material strength (a few MPa), down to depths of centimetres to a metre. The stress distribution with latitude is confirmed qualitatively when taking into account the comet’s complex shape but neglecting thermal inertia. Stress is found to be comparable to the material strength everywhere for sufficient thermal inertia (≳ 50 J m−2 K−1 s−1∕2) and ice content (≳ 45% at the equator). In this case, stresses penetrate to a typical depth of ~0.25 m, consistent with the detection of metre-scale thermal contraction crack polygons all over the comet. Thermal fracturing may be an important erosion process on cometary surfaces which breaks down material and weakens cliffs.
DOI Link: 10.1051/0004-6361/201731937
Rights: Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Licence URL(s): http://creativecommons.org/licenses/by/4.0/

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