by Staff Writers
Paris (ESA) Aug 03, 2012
ESA's Mars Express has observed the southern part of a partially buried approx. 440-km wide crater, informally named Ladon basin. The images, near to where Ladon Valles enters this large impact region reveal a variety of features, most notably the double interconnected impact craters Sigli and Shambe, the basins of which are criss-crossed by extensive fracturing.
This region, imaged on 27 April by the high-resolution stereo camera on Mars Express is of great interest to scientists since it shows significant signs of ancient lakes and rivers.
Both Holden and Eberswalde Craters were on the final shortlist of four candidate landing sites for NASA's Mars Science Laboratory, which is due now to land in Gale Crater on 6 August.
Large-scale overview maps show clear evidence that vast volumes of water once flowed from the southern highlands. This water carved Ladon Valles, eventually flowing into Ladon basin, an ancient large impact region.
Elliptical craters like this 16 km-wide example are formed when asteroids or comets strike the surface of the planet at a shallow angle. Scientists have suggested that a fluidised ejecta pattern indicates the presence of subsurface ice which melted during the impact. Subsequent impacts have created a number of smaller craters in the ejecta blanket.
The interconnected craters Sigli and Shambe are thought to have formed later when an incoming projectile split into two pieces just before impact. The joined craters were then partly filled with sediments at some later epoch.
Deep fractures can be seen within the craters whilst in the central and right part of the image, smaller craters and more subtle curved fractures appear.
These fractures on the basin floor extend beyond the image borders and form concentric patterns. The fractures are believed to have evolved by compaction of the huge sediment loads deposited within the impact basin
The outflow of Ladon Valles in to Ladon basin is located towards the east of Sigli and Shambe Craters, towards the bottom of this image. Here, and in several other parts of the image, lighter-toned layered deposits can be seen.
Researchers have detected clay minerals within these deposits, suggesting a relatively long-lasting presence of liquid water in the region's past.
In addition, winding, valley-like dendritic structures running into the larger basin can be seen above Sigli and Shambe Craters, running in to the larger impact basin, again indicating flowing water at some distant epoch.
Mars Express at ESA
Mars News and Information at MarsDaily.com
Lunar Dreams and more
Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.
Butterfly ejecta and wrinkle ridges in Melas Dorsa
Bonn, Germany (SPX) Jul 06, 2012
On 17 April 2012, the High Resolution Stereo Camera (HRSC) operated by the German Aerospace Center (Deutsches Zentrum fur Luft- und Raumfahrt; DLR) on board ESA's Mars Express spacecraft acquired images of a region in Melas Dorsa. Melas Dorsa is located in the volcanic highlands of Mars between Sinai and Thaumasia Plana, about 250 kilometres south of Melas Chasma, which is the central part of th ... read more
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2012 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement|