Ogygis Undae

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USGS map showing the location of Ogygis Undae on Mars Map of Ogygis Undae on Mars.PNG
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]

Contents

Morphology

Ogygis Undae is the final sink of an extended sand transport system that was imaged with the HRSC camera onboard ESA Mars Express. The complexity of this transport system is as extensive as some terrestrial examples. Dunes in Ogygis Undae have several morphologies including: barhcan, barchanoid, dome and 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.

Thermal emission spectroscopy results from the large dune field located inside Gale Crater were used as a reference for data obtained from Ogygis Undae because the features of Gale Crater were investigated extensively both by orbiting spacecraft and on site by the NASA Mars rover, Curiosity , a part of the Mars Science Laboratory (MSL) mission. [3] Ogygis Undae differs from the Gale dune field in both sand-type composition and homogeneity, indicating differences in both the types of sources for these dune fields as well as the distance from their respective sand-sources. [3] [5] The USGS investigators also noted that the dunes of Ogygis Undae look similar to the dunes in Grand Falls, Arizona. [3] [5]

See also

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Abalos Undae Martian dune field

Abalos Undae is a dune field on Mars in the periphery of Planum Boreum, the Martian North pole. It is one of the officially named northern circumpolar dune fields, along with Olympia, Hyperboreae, and Siton Undae, and also one of the densest of the region. Its northernmost boundary is located in the southwest channel that separates the Abalos Colles formation from the main polar ice cap, and from there the dune field extends southwest all the way to the lowlands of Vastitas Borealis.

Hyperboreae Undae Martian dune field

Hyperboreae Undae is one of the largest and densest dune fields of Planum Boreum, the Martian North Pole. It is named after one of the classical albedo features on Mars. Its name was officially approved by IAU in 1988. It extends from latitude 77.12°N to 82.8°N and from longitude 302.92°E to 316.02°E. Its centre is at latitude 79.96°N, longitude 49.49°W, and has a diameter of 463.65 kilometres (288.10 mi).

Siton Undae Martian dune field

Siton Undae is one of the largest and densest dune fields in the vicinity of Planum Boreum, the Martian northern polar ice-cap. It is named after one of the classical albedo features on Mars. Its name was officially approved by IAU on 20 March 2007. It extends from latitude 73.79°N to 77.5°N and from longitude 291.38°E to 301.4°E. Its centre is located at latitude 75.55°N, longitude 297.28E (62.72°W), and has a diameter of 222.97 kilometres (138.55 mi).

Aspledon Undae Martian dune field

Aspledon Undae is one of the named northern circumpolar dune fields in the vicinity of Planum Boreum, the Martian North pole. It is named after one of the classical albedo features on Mars. Its name was officially approved by the International Astronomical Union (IAU) on 20 March 2007. Its name is Greek, and derives from the name of a town in Boeotia, Ancient Greece, which, in turn, took its name from Aspledon, son of Poseidon, the ancient Greek god of the sea. The dunes of Aspledon Undae extend from latitude 71.47°N to 75.14°N and from longitude 305.83°E to 315.04°E. Its centre is located at latitude 73.06°N, longitude 309.65°E (50.35°W), and has a diameter of 215.2 km.

Abalos Mensa

Abalos Mensa is a wedge-shaped mound, or mensa and one of the named features in the vicinity of Planum Boreum, the Martian North pole. It is named after one of the classical albedo features on Mars. Its name was officially approved by IAU in 2006. It extends from latitude 80.21°N to 82.4°N and from longitude 279.34°E to 290.52°E. Its centre is located at latitude 81.17°N, longitude 284.4°E (75.6°W), and has a diameter of 129.18 km.

References

  1. ↑ "Nomenclature Search Results Target: MARS Feature Type: Unda, undae". Gazetteer of Planetary Nomenclature. USGS.
  2. 1 2 3 4 "Ogygis Undae". Gazetteer of Planetary Nomenclature. USGS.
  3. 1 2 3 4 5 6 7 8 9 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.CS1 maint: multiple names: authors list (link)
  4. 1 2 3 Silvestro, S.; Di Achille, G.; Ori, G.G. (September 2010). "Dune morphology, sand transport pathways and possible source areas in east Thaumasia Region (Mars)". Geomorphology. 121 (1–2): 84–97. doi:10.1016/j.geomorph.2009.07.019. ISSN   0169-555X.
  5. 1 2 3 Heather Charles, Timothy Titus, Rosalyn Hayward, Christopher Edwards, Caitlin Ahrens (15 January 2017). "Comparison of the mineral composition of the sediment found in two Mars dunefields: Ogygis Undae and Gale crater – three distinct endmembers identified". Earth and Planetary Science Letters. 458: 152–160. Bibcode:2017E&PSL.458..152C. doi:10.1016/j.epsl.2016.10.022.CS1 maint: multiple names: authors list (link)
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