Signs of water on the Martian surface

Signs of water on the Martian surface
During the early formation of Mars, vast volumes of water flowed across its surface in various regions. The Kasei Valley in the central Martian highlands, now dry, supports this fact. At the same time, and possibly in the more recent geological past, numerous volcanoes were active on Mars. Evidence of this is visible on the right hand side of this image, which shows an impact crater measuring about 30 kilometres in diameter, and now filled with solidified lava. If selected by NASA for the new Discovery mission, the Geophysical Monitoring Station (GEMS), would land on Mars in 2017 with the goal of investigating the interior of the Mars by conducting a series of geophysical experiments. This should answer questions about whether or not any water is still present. It could be there in the form of ice, stored in cavities below the surface. A better understanding of the development of volcanic activity throughout the history of Mars could also be achieved.
This perspective view of the Kasei Valley is based on stereo images from the High Resolution Stereo Camera (HRSC) system, operated by DLR on the European Mars Express spacecraft which has been orbiting Mars since the end of 2003.

ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO.