Publication Date:
2008-05-17
Description:
The Shallow Radar (SHARAD) on the Mars Reconnaissance Orbiter has imaged the internal stratigraphy of the north polar layered deposits of Mars. Radar reflections within the deposits reveal a laterally continuous deposition of layers, which typically consist of four packets of finely spaced reflectors separated by homogeneous interpacket regions of nearly pure ice. The packet/interpacket structure can be explained by approximately million-year periodicities in Mars' obliquity or orbital eccentricity. The observed approximately 100-meter maximum deflection of the underlying substrate in response to the ice load implies that the present-day thickness of an equilibrium elastic lithosphere is greater than 300 kilometers. Alternatively, the response to the load may be in a transient state controlled by mantle viscosity. Both scenarios probably require that Mars has a subchondritic abundance of heat-producing elements.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Phillips, Roger J -- Zuber, Maria T -- Smrekar, Suzanne E -- Mellon, Michael T -- Head, James W -- Tanaka, Kenneth L -- Putzig, Nathaniel E -- Milkovich, Sarah M -- Campbell, Bruce A -- Plaut, Jeffrey J -- Safaeinili, Ali -- Seu, Roberto -- Biccari, Daniela -- Carter, Lynn M -- Picardi, Giovanni -- Orosei, Roberto -- Mohit, P Surdas -- Heggy, Essam -- Zurek, Richard W -- Egan, Anthony F -- Giacomoni, Emanuele -- Russo, Federica -- Cutigni, Marco -- Pettinelli, Elena -- Holt, John W -- Leuschen, Carl J -- Marinangeli, Lucia -- New York, N.Y. -- Science. 2008 May 30;320(5880):1182-5. doi: 10.1126/science.1157546. Epub 2008 May 15.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Southwest Research Institute, Boulder, CO 80302, USA. roger@boulder.swri.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18483402" target="_blank"〉PubMed〈/a〉
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
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