A new image from the High Resolution Stereo Camera on ESA’s Mars Express orbiter shows the portion of the Cydonia Mensae, a region that is home to a long-debated formation known as the Face on Mars.
Part of the Cydonia Mensae region on Mars. The image was acquired by the Mars Express orbiter on 19 November 2014. Image credit: ESA / DLR / FU Berlin / IGO / CC BY-SA 3.0.
Cydonia Mensae is located in the Arabia Terra region and belongs to the transition zone between the southern highlands and the northern plains of the Red Planet. This transition is characterized by wide, debris-filled valleys and isolated remnant mounds (or mesas) of various shapes and sizes.
The region is thought to have hosted ancient seas or lakes that were later covered by hundreds of meters of thick lava and sediment deposits. These deposits were subsequently stripped away by water-driven erosion, leaving the wide debris-filled valleys, scattered mounds and flat-topped mesas of various shapes and sizes. Some of the remaining mounds have a different surface texture and a higher density of impact craters than their surroundings, suggesting that they were once part of the older southern highlands area.
In the center of the new image from the Mars Express there are two large mesas, each roughly 20 km across. Likely once joined together as single block, they are now split by a very broad valley.
At the right part of the image, a 15 km-wide impact crater displays interesting features. Inside its crater walls, material appears to have slumped away from the rim.
This context image shows the portion of the Cydonia Mensae region on Mars that was imaged by the Mars Express on 19 November 2014. Image credit: NASA / MGS / MOLA science team.
Meanwhile, the debris thrown out from the impact forms a double layer – an inner ejecta blanket covering a larger outer one.
Other smaller impact craters across the region also display smooth floors with raised rims and rounded rings of ejecta around them.
This characteristic form suggests that the impacts were into an ice- or water-saturated terrain, which became fluidized and mixed with the rock as the craters formed.
The dichotomy between the rugged southern highlands and smoother northern lowlands is crucial to understanding the overall geological history of the Red Planet, and regions like this transition zone in Cydonia provide a particularly rich set of important clues.
