Channels in Elysium Planitia

After the Odyssey spacecraft had completed a full Mars year of observations of the red planet Image of the Day looked back over this first mars year. Focus was on four themes: 1) the poles - with the seasonal changes seen in the retreatand expansion of the caps; 2) craters - with a variety of morphologies relating to impact materials and later alteration, both infilling and exhumation; 3) channels - the clues to liquid surface flow; and 4) volcanic flow features. While some images have helped answer questions about the history of Mars, many have raised new questions that are still being investigated as Odyssey continues collecting data as it orbits Mars.
The image shows an area in Elysium Planitia near Isidis Planitia. It was acquired May 17, 2002 during northern spring. The local time is 3:30pm. The image shows channels and collapsed lava-tubes. The channel formation is surface controlled, while the lava-tube creation is mainly structurally conrolled.