Moon is a 2009 film directed by Duncan Jones and starring Sam Rockwell. As lone technician on an otherwise automated Helium-3 facility on the Moon, Sam Bell maintains the facility and collects the H3 for transport back to Earth.
Moon is an unusual film in that it succeeds in telling a compelling story on a tight budget (5 million USD). While hardly breaking new ground in the science fiction arena, Moon's strength comes from the performance of technician Sam Bell, who seems to be experiencing some disturbing mental problems as his three-year contract draws to a close.
Adding to Sam's personal problems are the fact that realtime communication is down, necessitating recorded messages only, and Gerty, the laconic computer, seems to have the best interest of the company ahead of that of his human charge. Still, Sam goes about his daily routine, concentrating on the reunion of himself with his gorgeous Aussie wife and his toddler daughter, whom he has never met.
Note: This is a spoiler-free article. Revealing much more would instantly ruin the film if you've not seen it. Trust me.