When I first started drawing silly cartoons of the planets… err—I mean highly technical diagrams of celestial bodies—I had to chose which features to emphasize and which to leave out. For Mars, I ended up showing that distinctive orange/red coloration. What more would I need to show?
I decided to leave out the long, jagged scar cutting across the planet’s surface, in part because I thought it looked ugly. Maybe Mars feels the same way. In 1971, when NASA’s Mariner 9 space probe arrived to create the first detailed maps of the planet’s surface, Mars threw up a global dust storm unlike anything humans had ever seen before, completely obscuring all the planet’s surface features.
But as I’ve gotten to know Mars better, I’ve realized that Mars’s scar—the Valles Marineris canyon system, as its officially known—is really one of the Red Planet’s most important features. It’s as distinguishing a feature as the Great Red Spot on Jupiter or the giant heart on Pluto.
Valles Marineris is believed to have started out as a giant graben, or perhaps multiple smaller grabens, and it may have been one of the last geologically active regions on Mars (along with the neighboring Tharsis bulge). The end of Mars’s geological activity would have been related to the collapse of the planet’s magnetic field, which led to the loss of the Martian atmosphere and the rapid freezing/boiling of Mars’s oceans. If Mars ever had anything resembling an Earth-like biosphere, that would have been destroyed around that time too.
In other words, the story of how Mars got that scar may have a lot to tell us about Mars’s past, about the world Mars used to be. Over the last few months, I’ve experimented with different ways to depict Valles Marineris in my drawings. This is my favorite version:
Going forward, I’m going to include Valles Marineris in all my drawings of Mars (unless, of course, we’re highlighting a completely different region of the planet). Valles Marineris is just too important a thing to leave out. And also, scars are nothing to be ashamed of.