They don’t set movies on Mercury. Venus either. Or Jupiter or Saturn for that matter. Oh, certainly there are a few movies set on Venus. 2001 had the spaceship Discovery going to Jupiter, because Stanley Kubrick thought it would be too difficult to depict Saturn on the big screen. Doug Trumbull, who did the special effects for 2001, decided to set his own movie, Silent Running, at Saturn just to show it could be done (see “The green green grass of Earth”, The Space Review, March 2, 2009). There was also the barely tolerable Saturn 3 set at, well, Saturn—so that makes two for Saturn. And the ridiculously awful Event Horizon was set at Neptune, which provided a creepy backdrop for the haunted house in space story that had been done much better in numerous other movies. But you get the point: science fiction movies set in our own solar system don’t go to many planets.
They all go to Mars.
It is a cliché, but Mars captures the human imagination like no other planetary body except, maybe, the Moon. Other than Earth, it’s the planet that has been the subject of the most books and movies, a result of its ancient mystique and the fact that when you are outside on a very dark night, out in the middle of nowhere, where the city lights don’t spoil the night sky, Mars is so damn weird. A bright red spark that is both alluring and ominous.