Deuteronilus Mensae

Deuteronilus Mensae is a region on Mars 937 km across and centered at 43°54′N 337°24′W / 43.9°N 337.4°W / 43.9; -337.4. It covers 344° -325° West and 40°-48° North.^[1] Deuteronilus region lies just to the north of Arabia Terra and is included in the Ismenius Lacus quadrangle. It is along the dichotomy boundary, that is between the old, heavily cratered southern highlands and the low plains of the northern hemisphere. The region contains flat-topped knobby terrain that may have been formed by glaciers at some time in the past. Deuteronilus Mensae is to the immediate west of Protonilus Mensae and Ismeniae Fossae.^{[2] [3]} Glaciers persist in the region in modern times, with at least one glacier estimated to have formed as recently as 100,000 to 10,000 years ago.^[4] Recent evidence from the radar on the Mars Reconnaissance Orbiter has shown that parts of Deuteronilus Mensae do indeed contain ice.^[5][6]

Source of Ice

It is now widely believed that ice accumulated in many area of Mars, including Deuteronilus Mensae, when planet's orbital tilt was much different than it is now (the axis of Mars has considerable "wobble," meaning its angle changes over time).^{[7] [8] [9]} A few million years ago, the tilt of the axis of Mars was 45 degrees instead of its present 25 degrees. Its’ tilt, also called obliquity, varies greatly because its two tiny moons cannot stabilize it, like our relatively large moon does to the Earth. During periods of high tilt, the ice caps at the poles disappear, the atmosphere thickens, and the moisture in the atmosphere goes up. These conditions cause snow and frost to appear on the surface. Some of the moisture would have coated dust grains until the grains would be too heavy to be held up in the atmosphere; they would then fall and accumulate on the surface. Just plain snow would have also added to the mix. Ice on the surface of Mars today would immediately sublimate (or change directly into the gas phase). The rocky debris and dust covering ice is likely what has allowed it to survive below the surface for millions of years.

• 

  Deuteronilus Mensae, as seen by Mars Global Surveyor.

• 

  Deuteronilus Mensae ridges that suggest movement of deposits, as seen by THEMIS.

• 

  Small valleys in the wall of a crater in Deuteronilus Mensae, as seen by THEMIS.

• 

  Fretted terrain in Deuteronilus Mensae and Ismenius Lacus quadrangle showing flat floored valleys and cliffs. Photo taken with Mars Orbiter Camera (MOC)on the Mars Global Surveyor.

• 

  Enlargement of the photo on the left showing cliff. Photo taken with high resolution camera of Mars Global Surveyor (MGS).

• 

  CTX Context image of Deuteronilus Mensae showing location of next two images.

• 

  Eroded terrain in Deuteronilus Mensae, as seen by HiRISE, under the HiWish program.

• 

  Another view of eroded terrain in Deuteronilus Mensae, as seen by HiRISE, under the HiWish program.

• 

  CTX context image showing location of next two HiRISE images. Location is Ismenius Lacus quadrangle.

• 

  Possible moraine on the end of a past glacier on a mound in Deuteronilus Mensae, as seen by HiRISE, under the HiWish program. Location of this image is the box labeled A in previous image.

• 

  Complex surface around mound in Deuteronilus Mensae, as seen by HiRISE, under the HiWish program. Location of this image is in the black box labeled B in the CTX image above.

See also

• Geology of Mars
• Protonilus Mensae
• Martian dichotomy
• Ismenius Lacus quadrangle
• Glacier
• Nilosyrtis Mensae
• Glaciers on Mars

References

1. ^ Patrick Moore; Garry Hunt (1 January 1997). The atlas of the solar system. Chancellor. ISBN 9780753700143. http://books.google.com/books?id=jb87PgAACAAJ. Retrieved 21 March 2011. 
2. ^ Baker, M. et al. 2010. Flow patterns of lobate debris aprons and lineated valley fill north of Ismeniae Fossae, Mars: Evidence for extensive mid-latitude glaciation in the Late Amazonian. Icarus: 207. 186-209.
3. ^ http://www.esa.int/SPECIALS/Mars_Express/SEMBS5V681F_0.html
4. ^ Rincon, Paul (19 December 2007). "'Active glacier found' on Mars". BBC News. http://news.bbc.co.uk/1/hi/sci/tech/7151190.stm. 
5. ^ http://hirise.lpl.arizona.edu/PSP_009535_2240
6. ^ http://news.discovery.com/space/mars-ice-sheet-climate.html
7. ^ Madeleine, J. et al. 2007. Mars: A proposed climatic scenario for northern mid-latitude glaciation. Lunar Planet. Sci. 38. Abstract 1778.
8. ^ Madeleine, J. et al. 2009. Amazonian northern mid-latitude glaciation on Mars: A proposed climate scenario. Icarus: 203. 300-405.
9. ^ Mischna, M. et al. 2003. On the orbital forcing of martian water and CO2 cycles: A general circulation model study with simplified volatile schemes. J. Geophys. Res. 108. (E6). 5062.

External links

• Breathtaking views of Deuteronilus Mensae on Mars from Mars Express
• Scarps in Deuteronilus Mensae from HiRISE