Sam Rockwell has built a solid career of interesting performances in mediocre movies, and Duncan Jones’ decent Moon continues the trend. Rockwell plays Sam Bell, a technician toiling alone at a workstation on the moon where the terrain is mined for fuel used on Earth. Sam is less an astronaut than a lonely, half-crazed stiff working at a cruelly understaffed job, and his mental stability becomes even more tenuous when he finds his exact double wandering across the moon’s barren surface. Moon makes great, natural use of special effects on a relatively limited budget, and both the antiseptic ennui of Sam’s workstation and his morally ambivalent android assistant indicate Jones was aiming for a poor man’s 2001. But once the identity of the doppelganger is revealed, you realize there isn’t much to the film besides a clever gimmick.