Courtesy of Sony PicturesSam Rockwell in "Moon."
Moon, which opens on Friday, July 3, at the Mayan Theatre, is a low-budget science-fiction film that shoots for the stratosphere using ideas, not computer graphics and flashy effects. That it does so well with so little is a testament to the performance of Sam Rockwell, as an astronaut (or two) trying not to lose his marbles while working on an isolated mining station with no one to keep him company but GERTY, a robot programmed with the voice of