Mare Australe quadrangle

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Mare Australe quadrangle
USGS-Mars-MC-30-MareAustraleRegion-mola.png
Map of Mare Australe quadrangle from Mars Orbiter Laser Altimeter (MOLA) data. The highest elevations are red and the lowest are blue.
Coordinates 75°S 0°W / 75°S -0°E / -75; -0Coordinates: 75°S 0°W / 75°S -0°E / -75; -0
Image of the Mare Australe Quadrangle (MC-30). The region includes the South Polar ice cap. The central part is mainly a permanent residual ice cap surrounded by layered and troughed terrain which is, in turn, encircled by heavily cratered terrain.

The Mare Australe quadrangle is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey (USGS) Astrogeology Research Program. The Mare Australe quadrangle is also referred to as MC-30 (Mars Chart-30).[1] The quadrangle covers all the area of Mars south of 65°, including the South polar ice cap, and its surrounding area. The quadrangle's name derives from an older name for a feature that is now called Planum Australe, a large plain surrounding the polar cap.[2]

Notable features[edit]

Around the southern ice cap is a surface, called the Dorsa Argentea Formation that may be an old ice-rich deposit. It contains a group of sinuous, branched ridges that resembles eskers that form when streams are under glaciers.[3] The formation often contains pits: two major locations are named Cavi Angusti and Cavi Sisyphi. The pits have steep sides and an irregular shape. They are up to 50 km across and 1 km deep.[4]

The quadrangle also contains Angustus Labyrinthus, a formation of intersecting valley or ridges, nicknamed the "Inca City".[5] Researchers were surprised to see parts of the surface having a Swiss-cheese appearance. Also, some areas showed strange spider-shaped forms, which were determined to be caused by carbon dioxide gas blowing dust around at certain times of the year.

Some craters in Mare Australe show gullies. Martian gullies are small, incised networks of narrow channels and their associated downslope sediment deposits, found on the planet of Mars. They are named for their resemblance to terrestrial gullies. First discovered on images from Mars Global Surveyor, they occur on steep slopes, especially on the walls of craters. Usually, each gully has a dendritic alcove at its head, a fan-shaped apron at its base, and a single thread of incised channel linking the two, giving the whole gully an hourglass shape.[6] They are believed to be relatively young because they have few, if any craters. A subclass of gullies is also found cut into the faces of sand dunes which themselves considered to be quite young. On the basis of their form, aspects, positions, and location amongst and apparent interaction with features thought to be rich in water ice, many researchers believed that the processes carving the gullies involve liquid water. However, this remains a topic of active research. As soon as gullies were discovered,[6] researchers began to image many gullies over and over, looking for possible changes. By 2006, some changes were found.[7] Later, with further analysis it was determined that the changes could have occurred by dry granular flows rather than being driven by flowing water.[8][9][10] With continued observations many more changes were found in Gasa Crater and others.[11] With more repeated observations, more and more changes have been found; since the changes occur in the winter and spring, experts are tending to believe that gullies were formed from dry ice. Before-and-after images demonstrated the timing of this activity coincided with seasonal carbon-dioxide frost and temperatures that would not have allowed for liquid water. When dry ice frost changes to a gas, it may lubricate dry material to flow especially on steep slopes.[12][13][14] In some years frost, perhaps as thick as 1 meter.

Gallery[edit]

Spiders[edit]

Spiders[edit]

During the winter, much frost accumulates. It freezes out directly onto the surface of the permanent polar cap, which is made of water ice covered with layers of dust and sand. The deposit begins as a layer of dusty CO2 frost. Over the winter, it recrystalizes and becomes denser. The dust and sand particles caught in the frost slowly sink. By the time temperatures rise in the spring, the frost layer has become a slab of semi-transparent ice about 3 feet thick, lying on a substrate of dark sand and dust. This dark material absorbs light and causes the ice to sublimate (turn directly into a gas) Eventually much gas accumulates and becomes pressurized. When it finds a weak spot, the gas escapes and blows out the dust. Speeds can reach 100 miles per hour.[15] Dark channels can sometimes be seen; they are called "spiders."[16][17][18] The surface appears covered with dark spots when this process is occurring.[15][19] These features can be seen in some of the pictures below.

Proof for ocean[edit]

Strong evidence for a one time ancient ocean was found from data gathered from the north and south poles. In March 2015, a team of scientists published results showing that this region was highly enriched with deuterium, heavy hydrogen, by seven times as much as the Earth. This means that Mars has lost a volume of water 6.5 times what is stored in today's polar caps. The water for a time would have formed an ocean in the low-lying Mare Boreum. The amount of water could have covered the planet about 140 meters, but was probably in an ocean that in places would be almost 1 mile deep.

This international team used ESO’s Very Large Telescope, along with instruments at the W. M. Keck Observatory and the NASA Infrared Telescope Facility, to map out different forms of water in Mars’s atmosphere over a six-year period.[20][21]

Craters[edit]

Dust devil tracks[edit]

Craters showing layers[edit]

Craters showing defrosting in spring[edit]

See also[edit]

References[edit]

  1. ^ Davies, M.E.; Batson, R.M.; Wu, S.S.C. (1992). "Geodesy and Cartography". In Kieffer, H.H.; Jakosky, B.M.; Snyder, C.W. et al. Mars. Tucson: University of Arizona Press. ISBN 978-0-8165-1257-7. 
  2. ^ Patrick Moore and Robin Rees, ed. Patrick Moore's Data Book of Astronomy (Cambridge University Press, 2011), p. 130.
  3. ^ Kargel, J.; Strom, R. (1991). "Terrestrial glacial eskers: analogs for martian sinuous ridges" (PDF). LPSC XXII: 683–684. Bibcode:1991LPI....22..683K. 
  4. ^ Carr, Michael H. (2006). The Surface of Mars. Cambridge University Press. p. [page needed]. ISBN 978-0-521-87201-0. 
  5. ^ Hartmann, W. 2003. A Traveler's Guide to Mars. Workman Publishing. NY NY.
  6. ^ a b Malin, M., Edgett, K. 2000. Evidence for recent groundwater seepage and surface runoff on Mars. Science 288, 2330–2335.
  7. ^ Malin, M., K. Edgett, L. Posiolova, S. McColley, E. Dobrea. 2006. Present-day impact cratering rate and contemporary gully activity on Mars. Science 314, 1573_1577.
  8. ^ Kolb, et al. 2010. Investigating gully flow emplacement mechanisms using apex slopes. Icarus 2008, 132-142.
  9. ^ McEwen, A. et al. 2007. A closer look at water-related geological activity on Mars. Science 317, 1706-1708.
  10. ^ Pelletier, J., et al. 2008. Recent bright gully deposits on Mars wet or dry flow? Geology 36, 211-214.
  11. ^ NASA/Jet Propulsion Laboratory. "NASA orbiter finds new gully channel on Mars." ScienceDaily. ScienceDaily, 22 March 2014. www.sciencedaily.com/releases/2014/03/140322094409.htm
  12. ^ http://www.jpl.nasa.gov/news/news.php?release=2014-226
  13. ^ http://hirise.lpl.arizona.edu/ESP_032078_1420
  14. ^ http://www.space.com/26534-mars-gullies-dry-ice.html?cmpid=557882
  15. ^ a b http://themis.asu.edu/news/gas-jets-spawn-dark-spiders-and-spots-mars-icecap
  16. ^ Benson, M. 2012. Planetfall: New Solar System Visions
  17. ^ http://www.astrobio.net/topic/solar-system/mars/spiders-invade-mars/
  18. ^ Kieffer H, Christensen P, Titus T. 2006 Aug 17. CO2 jets formed by sublimation beneath translucent slab ice in Mars' seasonal south polar ice cap. Nature: 442(7104):793-6.
  19. ^ http://www.jpl.nasa.gov/news/news.php?release=2013-034
  20. ^ http://www.sciencedaily.com/releases/2015/03/150305140447.htm
  21. ^ . Villanueva, L., Mumma, R. Novak, H. Käufl, P. Hartogh, T. Encrenaz, A. Tokunaga, A. Khayat, M. Smith. Strong water isotopic anomalies in the martian atmosphere: Probing current and ancient reservoirs. Science, 2015 DOI: 10.1126/science.aaa3630
Mars Quad Map
About this image
0°N 180°W / 0°N 180°W / 0; -180
0°N 0°W / 0°N -0°E / 0; -0
90°N 0°W / 90°N -0°E / 90; -0
MC-01

Mare Boreum
MC-02

Diacria
MC-03

Arcadia
MC-04

Mare Acidalium
MC-05

Ismenius Lacus
MC-06

Casius
MC-07

Cebrenia
MC-08

Amazonis
MC-09

Tharsis
MC-10

Lunae Palus
MC-11

Oxia Palus
MC-12

Arabia
MC-13

Syrtis Major
MC-14

Amenthes
MC-15

Elysium
MC-16

Memnonia
MC-17

Phoenicis
MC-18

Coprates
MC-19

Margaritifer
MC-20

Sabaeus
MC-21

Iapygia
MC-22

Tyrrhenum
MC-23

Aeolis
MC-24

Phaethontis
MC-25

Thaumasia
MC-26

Argyre
MC-27

Noachis
MC-28

Hellas
MC-29

Eridania
MC-30

Mare Australe