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Friday, June 15, 2012

‘Danielson and Kalocsa’ the craters on Mars shows how the global climate change

A crater of image on Mars could hold evidence of how temperature evolves on the planet, variable considerably due to changes in the orientation of its axis of rotation. On June 19, 2011, Mars Express said its high-resolution stereo camera to the Arabia Terra region of Mars, photographed the craters Danielson and Kalocsa. The first is called the George E. Danielson, a key player in the development of several satellite cameras shipped in exploring the Red Planet. In this image from Mars Express, Danielson is the crater of the right (north), about 60 km in diameter.

The Kalocsa crater in the center of the image has a diameter of about 33 km and is a kilometer shallower than its neighbor. It is named after a Hungarian town, famous for its astronomical observatory.
Danielson craters environment and Kalocsa
Danielson, like many craters in the Arabia Terra region, is full of sediment that, in this case, has suffered serious erosion over time. Inside you can distinguish rocky formations with very peculiar stratification, known as yardangs. A yardang hill is a kind of stylized, carved into the bedrock of any material or semi-consolidated or consolidated by the abrasive action of particles of dust or windblown sand.
Here on Earth we find yardangs in desert regions, with clear examples in North Africa, Central Asia and in the Arizona desert in the United States.
In the case of Danielson crater, sediments may have been cemented by water from an underground aquifer before being eroded by the wind at a later stage of the geological history of the planet. The direction of the yardangs suggested to scientists that strong winds from north-northeast (in this picture, the bottom right corner) were responsible for both the original sediment deposition and its subsequent erosion, when the climate became driest. The image can also be seen a field of dunes, darker in color, about 30 kilometers long, which crosses the region yardangs. It is thought that this training had its origin in a much later stage.
Danielson Surveying and Kalocsa
In the bottom of the crater can distinguish a series of layers, separated and fairly uniform thickness that alternate their orientation. Some scientists think that these formations may indicate periodic fluctuations in the atmosphere of Mars caused by regular changes in the orientation of the axis of rotation of the planet.  So, would have been different strata deposited at different times of the planet's history.In this second crater layered deposits are not appreciated. It is thought that this could be due to the higher elevation of its base, which would have prevented that come into contact with the hypothetical aquifer sediments cemented underground Danielson crater.
Another hypothesis suggests that this crater is younger than its neighbor, having formed when there was no water in the region.

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