Bigger than the Grand Canyon

The solar system’s largest canyon system slices through the face of Mars’ northern hemisphere near the equator. On 2 May 2004, the High-Resolution Stereo Camera (HRSC) on board the ESA Mars Express spacecraft obtained images from the central area of the Mars canyon called Valles Marineris.

Overhead view of the solar system’s largest canyon system Credit: ESA

The canyon system of Valles Marineris is the largest and deepest known in solar system; extending more than 4,000 kilometers (2,500 miles) and has 5 to 10 kilometers (3 to 6 miles) relief from floors to tops of surrounding plateaus

The images were taken at a resolution of approximately 16 meters per pixel, or about the size of a school bus. The displayed region is located at the southern rim of the Melas Chasma at Mars latitude 12°S and Mars longitude 285°E. The images were taken on orbit 360 of Mars Express.

Mars Express has a primary mission to understand the atmosphere and volcanic effects using a combination of high resolution color imagery and spectrographic instruments.

This region shows several clues to the morphological and geological development of the Valles Marineris. The images show many traces of volcanic activity and possibly water-related acitivity. However, a lot of the surface has been altered by subsequent geological processes, such as wind erosion and quakes.

As Agustin Chicarro, Mars Express Project Scientist said, these "investigations will provide clues as to why the north of the planet is so smooth and the south so rugged…."

Although many questions about the geological development of the Valles Marineris canyon have remained unanswered until now, the detailed HRSC image data may help to find some answers. Using HRSC data, scientists can focus on morphology – the evolution of rocks and land forms. They can also analyze the light reflected by the canyon to understand which type of rocks it is made out of.

Valles Marineris
Credit: Olivier de Goursac and Adrian Lark in cooperation with the MOLA Science Team

During the recent NASA-sponsored debates on Mars terraforming, geoscientist James Kasting of Penn State commented about the stunning canyon system: "We’ll learn something by robotic missions, we’re learning lots right now from the current missions, but we won’t understand Mars like we understand the Earth until we get teams of geologists up there with rock hammers, clambering down Valis Marineris and looking at the whole stratigraphic sequence that is very difficult to get to robotically."

Such oblique views, resembling how a person looking out a window might view across the broad Martian horizon, have a special appeal, according to Dr. Bill Hartmann, a member of the imaging team that works with the Mars Global Surveyor." There are a number of regions I’d like to see photographed in that ‘human’ oblique view angle, the way we are used to seeing the land from our airplane windows. I think that they inspire a broader, more holistic view that lets us see Mars in the context of our terrestrial experience (not as an alien "target"), and that in turn inspires new thinking, a new sense of relationships, and new questions."

"I’d love to see obliques looking down Valles Marineris, across some of the big frosty craters, across some of the lava flows, down big riverbed channels like Ares Vallis and Ma’adim Vallis, and so on", concluded Hartmann.

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