lundi 3 août 2015

Fly over Atlantis Chaos












ESA - Mars Express Mission patch.

August 3, 2015

Ancient Atlantis

Mars is peppered with craters. Scientists have deduced that the red planet is struck by around 200 meteoroids every year that dig out new craters.

While some small craters are fresh, Mars has a great many that are much larger and more ancient, such as the roughly circular patch of terrain, partially encircled by wrinkled cliffs, shown at the centre of this image. Named Atlantis basin, this crater is so old that its outer rim has eroded and is now barely detectable. It is thought to be the result of a massive collision some 4 billion years ago, during the ‘Late Heavy Bombardment’ – a period when an unusually high number of asteroids rained down on the rocky inner Solar System planets.

The Atlantis basin is located in the southern highlands of Mars. Many different structures and geological features can be found across this region of the planet, a number of which are shown in this image such as cliffs, impact craters, channels carved into steep slopes, wrinkled ridges and scarps.

Perhaps the most prominent feature is the speckling of uneven terrain towards the centre of this image. This is Atlantis Chaos, a lowland plain covering around 170 km by 145 km, and containing a few hundred small peaks and flat-topped hills known as ‘mesas’. These sandy-coloured mounds are thought to result from the slow erosion of a once-continuous solid plateau.

Mars Express

There are several other large basins in this part of Mars that appear to be partially connected. Geologists believe that these basins may have been filled with water in the past to create the hypothetical far-reaching Eridania lake, which would have covered an area of over a million square kilometres, about the size of France and Spain combined.

There is also evidence from Mars Express and other spacecraft that deposits in one of these nearby basins contain minerals that are produced in the presence of water, and are similar to those found in some types of clay on Earth. This, along with the deep channels and ridges carved into the basin slopes seen towards the bottom of this image, for example, suggest the past existence of water in the Atlantis basin and surrounding region.

This image is a mosaic of four images taken by the Mars Express High Resolution Stereo Camera on 28 December 2008, 29 December 2008, 6 February 2009 and 5 January 2014. The image resolution is roughly 14 m per pixel.

Chaos in Atlantis basin

This colourful image is a topography map of a portion of the region known as Terra Sirenum, located in the southern hemisphere of Mars. The map is colour-coded, with reds and whites representing the highest topography and blues and purples the lowest.

The images shows a myriad of terrain types including cliffs, impact craters, channels carved into steep slopes, wrinkled ridges and scarps, which together reflect a rich geological history.

Perhaps the most prominent feature is the portion of uneven chaotic terrain towards the centre of the image. This is Atlantis Chaos, a lowland plain covering around 170 km by 145 km and containing a few hundred small peaks and flat-topped hills. They are thought to result from the slow erosion of a once-continuous solid plateau.

A number of impact craters occupy the scene and span a range of ages, with the most ancient with almost undetectable rims that have eroded over time. Indeed, the outline of the giant Atlantis Basin is hard to see, but lies at the centre of the image and spans over 200 km. It is connected to another large basin located further south (left) with a diameter of 175 km.

Scientists suspect that some of the craters and basins in this area may have once contained standing water. Indeed, channels carved into the slopes of the ancient basins provide evidence for the existence of water in this region’s past.

This image is a mosaic of four images taken by the Mars Express High Resolution Stereo Camera on 28 December 2008, 29 December 2008, 6 February 2009 and 5 January 2014. The image resolution is roughly 14 m per pixel.

Flight over Atlantis Chaos

Video above: Explore the Atlantis Chaos region of Mars, in the Red Planet’s southern hemisphere. The video showcases a myriad of features that reflect a rich geological history. The tour takes in rugged cliffs and impact craters, alongside parts of ancient shallow, eroded basins.

See smooth plains scarred with wrinkled ridges, scarps and fracture lines that point to influence from tectonic activity. Marvel at ‘chaotic’ terrain – hundreds of small peaks and flat-topped hills that are thought to result from the slow erosion of a once-continuous solid plateau. This entire region may once have played host to vast volumes of water – look out for the evidence in the form of channels carved into steep-sided walls.

Related links:

Looking at Mars: http://www.esa.int/Our_Activities/Space_Science/Mars_Express

High Resolution Stereo Camera: http://berlinadmin.dlr.de/Missions/express/indexeng.shtml

Behind the lens...: http://www.esa.int/Our_Activities/Space_Science/Mars_Express/Behind_the_lens

Frequently asked questions: http://www.esa.int/Our_Activities/Space_Science/Mars_Express/Frequently_asked_questions

ESA Planetary Science archive (PSA): http://www.rssd.esa.int/PSA

NASA Planetary Data System: http://pds-geosciences.wustl.edu/missions/mars_express/hrsc.htm

HRSC data viewer: http://hrscview.fu-berlin.de/

In depth:

Mars Express in depth: http://sci.esa.int/science-e/www/area/index.cfm?fareaid=9

Mars Express top 10 discoveries: http://sci.esa.int/jump.cfm?oid=51820

Images, Video, Text, Credits: ESA/DLR/FU Berlin (CC BY-SA 3.0 IGA).

Greetings, Orbiter.ch

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