Mars Express High Resolution Stereo Camera image of Hebes Chasma.Hebes Chasma is an enclosed trough, almost 8000 m deep, in Valles Marineris, the Grand Canyon of Mars, showing Light Toned Deposits. This is an area where water is believed to have flowed. An analysis of data and images from Mars Express suggests that several Light Toned Deposits, some of the least understood structures on Mars, were formed when large amounts of groundwater burst on to the surface. Scientists propose that groundwater had a greater role in shaping the Martian surface than previously believed, and may have sheltered primitive life forms as the planet started drying up. Hebes Chasma is located at approximately 1° south and 282° east. Image data was obtained on 16 September 2005 with a ground resolution of approximately 15 m/pixel.