This article will be permanently flagged as inappropriate and made unaccessible to everyone. Are you certain this article is inappropriate? Excessive Violence Sexual Content Political / Social
Email Address:
Article Id: WHEBN0014796218 Reproduction Date:
Deuteronilus Mensae is a region on Mars 937 km across and centered at . 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][7]
It is now widely believed that ice accumulated in many areas of Mars, including Deuteronilus Mensae, when the planet's orbital tilt was very different from now (the axis of Mars has considerable "wobble," meaning its angle changes over time).[8][9][10] 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 the Earth.
Many features on Mars, including Deuteronilus Mensae, are believed to contain large amounts of ice. The most popular model for the origin of the ice is climate change from large changes in the tilt of the planet's rotational axis. At times the tilt has even been greater than 80 degrees[11][12] Large changes in the tilt explains many ice-rich features on Mars.
Studies have shown that when the tilt of Mars reaches 45 degrees from its current 25 degrees, ice is no longer stable at the poles.[13] Furthermore, at this high tilt, stores of solid carbon dioxide (dry ice) sublimate, thereby increasing the atmospheric pressure. This increased pressure allows more dust to be held in the atmosphere. Moisture in the atmosphere will fall as snow or as ice frozen onto dust grains. Calculations suggest this material will concentrate in the mid-latitudes.[14][15] General circulation models of the Martian atmosphere predict accumulations of ice-rich dust in the same areas where ice-rich features are found.[16] When the tilt begins to return to lower values, the ice sublimates (turns directly to a gas) and leaves behind a lag of dust.[17][17][18] The lag deposit caps the underlying material so with each cycle of high tilt levels, some ice-rich mantle remains behind.[19] Note, that the smooth surface mantle layer probably represents only relative recent material.
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.
Hollowed out terrain in Deuteronilus Mensae, as seen by HiRISE under HiWish program.
Large group of concentric cracks, as seen by HiRISE, under HiWish program.
Solar System, Mars Reconnaissance Orbiter, Oxygen, Mercury (planet), Moon
Mars, Mare Boreum quadrangle, Diacria quadrangle, Arcadia quadrangle, Mare Acidalium quadrangle
Mars, Mars Science Laboratory, Nasa, Mars Express, 2001 Mars Odyssey
Mars, Syrtis Major quadrangle, Amazonis quadrangle, Margaritifer Sinus quadrangle, Mars Reconnaissance Orbiter
Mars, European Space Agency, Mars Science Laboratory, ExoMars, Beagle 2
Mars, Ismenius Lacus quadrangle, HiWish program, Moons of Mars, HiRISE
Mars, Casius quadrangle, Antarctica, Water on Mars, Moons of Mars
Mars, Geology of Mars, Water on Mars, Moons of Mars, Mars Scout Program
Mars, Ismenius Lacus quadrangle, Lunae Palus quadrangle, Volcanology of Mars, Moons of Mars
Mars, Lobate debris apron, Deuteronilus Mensae, Impact crater, Lineated valley fill