Please use this identifier to cite or link to this item: http://hdl.handle.net/1893/27540
Appears in Collections:Biological and Environmental Sciences Journal Articles
Peer Review Status: Refereed
Title: Impact cratering experiments in brittle targets with variable thickness: Implications for deep pit craters on Mars
Author(s): Michikami, Tatsuhiro
Hagermann, Axel
Miyamoto, Hideaki
Miura, Seiichi
Haruyama, Junichi
Lykawka, Patryk S
Keywords: Impact cratering process
pit crater
penetration regime
subsurface cavity
laboratory experiments
Issue Date: 30-Jun-2014
Citation: Michikami T, Hagermann A, Miyamoto H, Miura S, Haruyama J & Lykawka PS (2014) Impact cratering experiments in brittle targets with variable thickness: Implications for deep pit craters on Mars, Planetary and Space Science, 96, pp. 71-80. https://doi.org/10.1016/j.pss.2014.03.010.
Abstract: High-resolution images reveal that numerous pit craters exist on the surface of Mars. For some pit craters, the depth-to-diameter ratios are much greater than for ordinary craters. Such deep pit craters are generally considered to be the results of material drainage into a subsurface void space, which might be formed by a lava tube, dike injection, extensional fracturing, and dilational normal faulting. Morphological studies indicate that the formation of a pit crater might be triggered by the impact event, and followed by collapse of the ceiling. To test this hypothesis, we carried out laboratory experiments of impact cratering into brittle targets with variable roof thickness. In particular, the effect of the target thickness on the crater formation is studied to understand the penetration process by an impact. For this purpose, we produced mortar targets with roof thickness of 1-6 cm, and a bulk density of 1550 kg/m3 by using a mixture of cement, water and sand (0.2 mm) in the ratio of 1:1:10, by weight. The compressive strength of the resulting targets is 3.2±0.9 MPa. A spherical nylon projectile (diameter 7 mm) is shot perpendicularly into the target surface at the nominal velocity of 1.2 km/s, using a two-stage light-gas gun. Craters are formed on the opposite side of the impact even when no target penetration occurs. Penetration of the target is achieved when craters on the opposite sides of the target connect with each other. In this case, the cross section of crater somehow attains a flat hourglass-like shape. We also find that the crater diameter on the opposite side is larger than that on the impact side, and more fragments are ejected from the crater on the opposite side than from the crater on the impact side. This result gives a qualitative explanation for the observation that the Martian deep pit craters lack a raised rim and have the ejecta deposit on their floor instead. © 2014 Elsevier Ltd. All rights reserved.
DOI Link: 10.1016/j.pss.2014.03.010
Rights: This article is available under the terms of the Creative Commons Attribution License (CC BY). You may distribute and copy the article, create extracts, abstracts, and other revised versions, adaptations or derivative works of or from an article (such as a translation), to include in a collective work (such as an anthology), to text or data mine the article, including for commercial purposes without permission from Elsevier. The original work must always be appropriately credited.

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