The maps that chart the geology and topography of Mars are nearly indecipherable to those who are not scientifically inclined. Until now. Ordnance Survey, Britain’s national mapping agency, has created what might be the first map of Mars designed for the average person.
The map charts a 2,281- by 1,690-mile expanse of the Red Planet. The region is roughly the size of the United States, and encompasses several prospective landing sights for future Mars missions. Despite charting alien terrain, the map‘s dusty colors, blue grid lines, and sans-serif typefaces feel familiar—as though you’re looking at a map of a state, if that state happened to be dotted by mile-wide craters. Chris Wesson, a cartographic designer with Ordnance Survey, says that sense of recognition is intentional. “You can almost imagine what the place might look like,” he says. “I guess that’s what ours does that perhaps a more scientific map cannot do.”
The map is based on data collected by spacecraft in orbit around Mars. It’s the same data used in other maps of the planet, like this 2014 geologic map from the US Geological Survey. But where the USGS map paints a story of Mars’s geologic makeup over time—charting volcanic lava deposits, icy polar outcrops, and everything in between—the Ordnance Survey map tells a simpler story. Like a map you might find in your glovebox, its color scheme and shading give prominence to metrics like distance and elevation. A familiar cyan grid overlays its surface. Its legend makes no reference to things like “summit collapse,” “magma withdrawal,” or “fluvial dissection.”
“It’s not that the content is different,” says Jim Skinner, a research scientist with USGS. “It’s just the way that it’s presented is different.”
Though it’s meant to look intentionally familiar, Wesson says where the Ordnance Survey’s Mars maps differs from something like a map of the Scottish Highlands is the fact that there are very few landscape features on Mars aside from craters, canyons, and peaks.. “I really didn’t have a lot of data to work with aside from elevation,” he says. On Earth things like bodies of water, woodlands, deserts, and mountains give maps their visual distinction. Not surprisingly, this Mars map is striking in its simplicity. It uses continuous layers of color to denote elevation, ranging from green (lowest) to a dusty red (highest). At the very highest peaks, Wesson added a touch of white to imply that at some point in history there might have been frozen water there. He was careful to avoid blue, which tends to indicate water on terrestrial maps.
At its lowest, the elevation of the map is nearly 3.5 miles below Mars’ zero level—the Martian equivalent of sea level—and the highest is than 2 miles above it. On the map you can see that the elevation is greatest in the southeastern portion of the map, the yellow across the center representing some form of zero level.
The map’s scale is 1 to 4 million. To put that in perspective, the Schiaperelli crater in the bottom righthand corner of the map measures 310 miles across. Skinner says a map like this is useful for getting a high-level contextual understanding of the territory. It’s not accurate at the surface—the resolution of the laser altimeter data gathered by the orbiter is too low (about half a kilometer per pixel, he says). “So if Mark Watney from The Martian was standing on the surface, he wouldn’t be using this data because the resolution of this data is not at scale with what he would be standing on,” Skinner says. It’s not a suitable map to use for navigating a rover or figuring out where humans might put a habitation unit, but it is good for establishing context.
And indeed, the Ordnance Survey says it’s really meant to be a base map, upon which additional data sets can be layered. Eventually they hope that scientists might adopt it, using it it as the standard to chart high-level rover paths, for example. In the meantime, us mere mortals have few actual uses for it, but it would look awfully pretty hung on a wall.