Today's Image of Mars is a north-looking perspective view of Juventae Chasma, a large fissure that cuts 5000m into Lunae Planum on Mars and measures 180km east-west and 250km north-south.
Juventae Chasma obvious interaction with water led NASA to consider it as a candidate destination for Mars Science Laboratory Curiosity. Though it was not selected to be the MSL landing spot, there is still much to be learned from the chasm.
Scientists believe that sometime 3-4 billion years ago Juventae Chasma was filled with water, which then created the large deposits of clays, gypsum, and other sulfate minerals we see today. They have speculated that Juventae once had a habitat that was suitable to life, which keeps it on the list of potential landing sites for future missions to Mars.
How did Juventae Chasma form?
Scientists speculate that Juventae Chasm formed as a result of faulting and volcanic heat opening up cracks in the surface, which then let water and subsurface ice out, causing the surface to collapse from the floods that resulted. There was enough water that it poured out of the northern end and created the outflow channel, Maja Valles, which flows all the way to the Chryse impact basin.
Eventually Juventae Chasma stopped growing, but the water within the canyon altered the rocks and surface materials, turning them into the gypsum and other aqueous material we see today.
The ridge you see in the northeast of Juventae Chasma's valley measures 59km long, 23km wide, and 2500m high, making it half as high as the chasm's walls.. This mountain became of interest to scientists when they determined that it was composed of sulfate deposits.
On the top part of the ridge, Mars Express' OMEGA instrument detected gypsum, with 12 distinct layers present. Below the gypsum layers lies kieserite, a form of magnesium sulfate. Both gypsum and kieserite are classified as evaporates, meaning that they often form where lakes of salty water dry up.
The potential landing site for future missions to Mars lies on the southern tip of this ridge. Any rover would then likely move along the western side of the ridge where there are numerous layered deposits that could provide answers as to whether Mars ever sustained life.
This image was taken by the High Resolution Stereo Camera (HRSC) aboard Mars Express. Clicking on the image will take you to the original high resolution image from them.