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TOPIC: Mars


L

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RE: Mars
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A new research led by a UK scientist has indicated that Mars had significantly warmer weather in its recent past than previously thought.
Dr Matthew Balme, from The Open University, made the new discovery by studying detailed images of equatorial landforms that formed by melting of ice-rich soils.
His work indicates that the Martian surface experienced "freeze thaw" cycles as recently as 2 million years ago, and that Mars has not been locked in permafrost conditions for billions of years as had been previously thought.

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Lightning on Mars
U.S. scientists say they have detected the first direct evidence of lightning occurring on Mars.
University of Michigan researchers said they found signs of electrical discharges during dust storms on the red planet. The bolts were dry lightning, Professor Chris Ruf said.

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Hephaestus Fossae
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Craters and channels in Hephaestus Fossae
Hephaestus Fossae ortho-image
Hephaestus Fossae ortho-image

5 June 2009
The High Resolution Stereo Camera on ESA's Mars Express orbiter has obtained images of Hephaestus Fossae, a region on Mars dotted with craters and channel systems.
Hephaestus Fossae lies at about 21 North and 126 East on the Red Planet. Named after the Greek god of fire, it extends for more than 600 km on the western flank of Elysium Mons in the Utopia Planitia region.
Obtained on 28 December 2007, the images have a ground resolution of about 16 m/pixel. They show that the region has channel systems of unknown origin.

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NASA Scientists Find Evidence for Liquid Water on a Frozen Early Mars
NASA scientists modelled freezing conditions on Mars to test whether liquid water could have been present to form the surface features of the Martian landscape.
Researchers report that fluids loaded with dissolved minerals containing elements such as silicon, iron, magnesium, potassium and aluminium, can remain in a liquid state at temperatures well below freezing. The results of this research appear in the May 21 issue of Nature magazine entitled "Stability Against Freezing of Aqueous Solutions on Early Mars."


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Zumba crater
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Fresh Secondary Crater of Zumba Crater in Daedalia Planum
Fresh Secondary Crater of Zumba Crater in Daedalia Planum (PSP_004874_1505)
Credit: NASA/JPL/University of Arizona


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This image taken at a high sun angle shows the relatively unshadowed pristine and youthful rayed crater Zumba.
The crater's rim-to-rim diameter is approximately 3 kilometres with a depth of about 620 metres, and its rim rises about 200 metres above the surrounding lava-filled plains of Daedalia Planum, just southwest of the great Tharsis volcanoes. (For an appreciation of the dimensions of this crater, see the anaglyph for Zumba.) Zumba is approximately 25% deeper than the average Martian crater of this size - just one of several attributes that suggests it is a very fresh crater.

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RE: Mars
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In a new research, scientists suggest that a "supergiant" asteroid several times larger than the one that likely killed the dinosaurs struck Mars with such force that it shut down the planets magnetic field.
Based on the number of large craters present, scientists think very early Mars suffered 15 or so giant impacts within a span of about a hundred million years.
Now, according to a report in National Geographic News, a new computer model suggests that Marss magnetic field may have been slowly weakened by four especially large impacts and then snuffed out completely by a fifth and final blow.


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Crater Asimov
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The International Astronomical Union (IAU) has approved the name Asimov for the 84-kilometre wide Martian crater located at 47.0S, 355.0W.
The crater is named after Isaac Asimov (1920-1992).

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RE: Mars
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Chaotic terrain in Ariadnes Colles
Ariadnes Colles, nadir view
Ariadnes Colles, nadir view

These images, taken by the Mars Express High Resolution Stereo Camera, show the region of Ariadnes Colles on the Red Planet.
The image data were acquired on 16 April 2007 and are centred at 34 south and 172 east. The ground resolution is about 13 m/pixel.

A slow-motion video of lightning by the University of Florida's Centre for Precollegiate Education and Training.

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Early Mars Environment
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Title: Astrobiological Implications of Early Mars Environment
Authors: Helmut Lammer

The history of the Martian atmosphere can be divided into Noachian, Hesperian, and Amazonian evolutionary periods. During the Noachian period, Mars and its surrounding atmosphere were altered by collisions with asteroids and comets, and the young Suns elevated X-ray and extreme ultraviolet (EUV) radiation and solar wind. After the Sun arrived at the Zero-Age-Main-Sequence (ZAMS), heavy noble gases, like nonradiogenic Xe isotopes, may have been hydrodynamically fractionated during the accretion phase of the planet to their present composition, with corresponding depletions and fractionations of lighter primordial atmospheric species such as deuterium (D) or H atoms.
Subsequently, the CO2 surface-pressure history and the isotopic evolution of atmospheric species during this early period were determined by the interplay between impact erosion and impact delivery, carbonate precipitation and oxidation, outgassing and carbonate recycling, and perhaps by feedback stabilization under greenhouse conditions (Carr, 1987; Pepin, 1994; Manning et al., 2006). This period was also influenced by thermal and nonthermal atmospheric loss processes (e.g., Donahue, 2004; Kulikov et al., 2007; Lammer et al., 2008), which would depend partly on the time of the on-set of the martian magnetic dynamo, the field strength and decrease time of the magnetic moment, and the radiation and particle environment of the young Sun.
The second period in the evolution of the martian atmosphere can be characterised by a uniform atmospheric loss, which was enhanced due to the vanished intrinsic magnetic field and various nonthermal atmospheric escape processes that resulted in the present surface pressure of about 710 mbar.

Helmut Lammer. Astrobiology. January/February 2009, 9(1): 42-44. doi:10.1089/ast.2009.0923.

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Holden Crater
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Holden is a 140 km wide crater on Mars, located with the southern highlands. It is named after Edward Singleton Holden, an American astronomer, and the founder of the Astronomical Society of the Pacific. Like Gusev, it is notable for an outlet channel, Uzboi Vallis, that runs into it, and for many features that seem to have been created by flowing water. The crater's rim is cut with gullies, and at the end of some gullies are fan-shaped deposits of material transported by water. The crater is of great interest to scientists because it has some of the best-exposed lake deposits. One of the layers has been found by the Mars Reconnaissance Orbiter to contain clays. Clays only form in the presence of water. It is believed that great amount of water went through this area; one flow was caused by a body of water larger than Earth's Lake Huron. Holden is an old crater, containing numerous smaller craters, many of which are filled with sediment. The crater's central mountain is also obscured by sediment. Holden Crater is a proposed landing site for NASA's Mars Science Laboratory.

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