The first humans on Mars had a good idea of what to expect. Or at least they thought they knew. The canals had been well studied by robot and remote camera before any boots hit the red, rocky soil. The evidence for and against the habitation of Mars had been studied, and the papers had settled the question. Science had proven that Humanity was alone in the solar system. Except for maybe Ganymede, of course. But while science was sure that the famous canals were a natural formation, the team was unable to explain the presence of the water skis.