Publikationsdatum:
2007-11-03
Beschreibung:
The equatorial Medusae Fossae Formation (MFF) is enigmatic and perhaps among the youngest geologic deposits on Mars. They are thought to be composed of volcanic ash, eolian sediments, or an ice-rich material analogous to polar layered deposits. The Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) instrument aboard the Mars Express Spacecraft has detected nadir echoes offset in time-delay from the surface return in orbits over MFF material. These echoes are interpreted to be from the subsurface interface between the MFF material and the underlying terrain. The delay time between the MFF surface and subsurface echoes is consistent with massive deposits emplaced on generally planar lowlands materials with a real dielectric constant of approximately 2.9 +/- 0.4. The real dielectric constant and the estimated dielectric losses are consistent with a substantial component of water ice. However, an anomalously low-density, ice-poor material cannot be ruled out. If ice-rich, the MFF must have a higher percentage of dust and sand than polar layered deposits. The volume of water in an ice-rich MFF deposit would be comparable to that of the south polar layered deposits.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Watters, Thomas R -- Campbell, Bruce -- Carter, Lynn -- Leuschen, Carl J -- Plaut, Jeffrey J -- Picardi, Giovanni -- Orosei, Roberto -- Safaeinili, Ali -- Clifford, Stephen M -- Farrell, William M -- Ivanov, Anton B -- Phillips, Roger J -- Stofan, Ellen R -- New York, N.Y. -- Science. 2007 Nov 16;318(5853):1125-8. Epub 2007 Nov 1.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Center for Earth and Planetary Studies, National Air and Space Museum, Smithsonian Institution, Washington, DC 20560, USA. watterst@si.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17975034" target="_blank"〉PubMed〈/a〉
Schlagwort(e):
Extraterrestrial Environment
;
Geologic Sediments
;
Ice
;
*Mars
;
Radar
Print ISSN:
0036-8075
Digitale ISSN:
1095-9203
Thema:
Biologie
,
Chemie und Pharmazie
,
Informatik
,
Medizin
,
Allgemeine Naturwissenschaft
,
Physik
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