What I just realized is that in all my years of amateur adventuring and digging into abandoned and forbidden places–Mayan cities, Montauk Point, various ruins both remote and urban, ancient or merely obsolete–I can’t remember a single time I’ve mistaken a large natural object for an artifact. The reverse, certainly, as nature reclaims all our works sooner or later. But as soon as you recognize an artifact, you know it’s an artifact, no question. If there was anything constructed on Mars, anything just laying about on the surface, it would jump out at us at far less resolution than we’ve already achieved. I think Mars gazers must suffer from a unique brand of synethesia to find patterns in these images.