The Iani Chaos region on Mars would be a great place to hike, if you could get there. The ancient flow of water has collapsed the surface, carving blocks and mesas as well as creating valleys and washes that would take years to thoroughly explore. Now, using imagery captured by the High Resolution Stereo Camera (HRSC) on the European Space Agency's Mars Express Orbiter, scientists have compiled the first topographical maps of Mars—focusing on Iani Chaos.

Over the past three years, the HRSC has snapped huge swaths of Martian terrain. "This stereo camera has five eyes," says planetary scientist Gerhard Neukum of Freie Universitt Berlin, who developed the HRSC. "It has 38 degrees total stereo angle, which is very good compared to the human eye." Just as the slight displacement of two eyes allows humans to see in depth, the HRSC's five "eyes" allow it to create deep images of the Red Planet's surface.

Previously, laser altimetry had been used to get a rough estimate of the relative depth and height of various Martian landmarks, but this method was imprecise, taking readings every 100 meters or so at best. The HRSC can include as little as 10 meters in just one pixel, according to Neukum. "What we will get in the end," he says, "is total coverage of Mars in color imagery in stereo from which we can derive digital terrain models at resolutions of 10 to 20 meters per pixel."

As a test, Neukum and his colleagues used the HRSC images of Iani Chaos to create a detailed map of the contours of this fractured area. Such maps are familiar to hikers the world over. The high resolution images enabled the researchers to create "topo maps" as detailed as the one to 50,000 maps available here on Earth, where one unit on the map, say meters, equals 50,000 of that unit on the planet's surface, be it height, depth or distance.

This is not just an exercise for nonexistent hikers; the new maps provide information that previously was sketchy at best. "People will know exactly when they have a rover on the surface how steep the slopes are and how high the mountains are," Neukum notes. "Previously, they had to learn that the hard way—by trial and error." Neukum and his colleagues expect to complete imaging the entire surface within four (Earth) years. There are no plans yet to create topographic maps of the entire planet, but it would be a prerequisite of any manned mission to Mars. "If we want to put people on the surface," he says, "this is an absolute necessity." Happy trails.