TheESA Mars Express probehas submitted new images of a crater showing what may have been the bed of a large lake at the time when water flowed across the surface of Mars.
The images have been taken in theEberswalde crater, in the southern highlands of Mars, 65 kilometers in diameter. The crater was formed more than 3.7 billion years ago after the impact of an asteroid. A subsequent impact resulted in Holden Crater, 140 kilometers in diameter. The rocks removed by this second impact covered much of the Eberswalde crater.
However, in the still visible fragment of Eberswalde theremains of what was once a great delta, crossed by multiple river arms, as can be seen in the upper right section of the image. This delta covers an area of about 115 square kilometers. The meandering riverbeds to the north of the crater fed it with water, giving rise to a large lake.
When the lake dried up, much of the delta and its riverbeds were hidden under a new layer of sediment, swirled by the wind. These secondary deposits have suffered the action of erosion, exposing the inverted structure that we can observe today. This structure, first identified by the probeMars Global Surveyor from NASA, shows that the crater was once a lake bed, and is unequivocal proof that water once flowed on the surface of Mars.
The Eberswalde and Holden craters are two of the four sites selected for the landing of theNASA’s next rover, which will take off later this year. The main objective ofMars Science Laboratory (MSL) It is the study of regions that are or could have been habitable. The missionMars Express ESA helps to select which of the possible sites is the most interesting.
