Ogygis Undae

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USGS map showing the location of Ogygis Undae on Mars

Ogygis Undae is the only named southern hemisphere

dune field on Mars.[1] It is named after one of the classical albedo features on Mars, Ogygis Regio.[2] Its name, which refers to Ogyges, a primeval mythological ruler in ancient Greece,[2] was officially approved by the International Astronomical Union (IAU) on September 17, 2015. It is situated just outside Argyre Planitia, a plain located in the southern highlands of Mars.[3] The dunes of Ogygis Undae extend from latitude −49.94°N to −49.37°N and from longitude 292.64°E to 294.93°E (65.07°W – 67.36°W).[2] They are centered at latitude −49.66°N, longitude 293.79°E (66.21°W), and extend approximately 87 km to the east and west from there.[4][2] Ogygis Undae has an area of 1904 km2, and due to its large size is a primary subject for research on Martian dune morphology and sand composition.[4][3]

Morphology

Ogygis Undae is the final sink of an extended sand transport system that was imaged with the

star dunes. The variety of dune types indicates that they were deposited in a multimodal wind regime with different winds converging into the basin where the dunes are located, carrying sand from multiple source areas.[4] The morphological complexity is mirrored by the diverse mineral composition of the dune-forming sediment.[3]

Composition

Mineral distribution across the dune fields of Ogygis Undae is non-uniform and bimodal.[3] The relative juxtaposition of the two primary grain types reveals how Aeolian processes affect the transport of sand on the surface of Mars.[3] Compositional spectra were acquired and analyzed in 2016 by USGS scientists using both the Thermal Emission Spectrometer (TES) instrument on board Mars Global Surveyor and the Thermal Emission Imaging System (THEMIS) on board the 2001 Mars Odyssey spacecraft.[3][5] Other characteristics of Ogygis Undae, such as its nocturnal thermal inertia values, corroborate the finding that there is a bimodal sand-type distribution across the field.

Grand Falls, Arizona.[3][5]

See also

References

  1. USGS
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  2. ^
    USGS
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  3. ^ a b c d e f g h i H. R. Charles, T. N. Titus, R. K. Hayward, and C. S. Edwards. "Comparison of the Mineral Composition of the Sediment Found in Two Mars Dunefields: Ogygis Undae and Gale Crater" (PDF). 47th Lunar and Planetary Science Conference (2016). USGS.{{cite web}}: CS1 maint: multiple names: authors list (link)
  4. ^
    ISSN 0169-555X
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  5. ^
    doi:10.1016/j.epsl.2016.10.022.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
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