Tim:
Read the book, it's much more comprehensive than the film (which was shortened, significantly). There's a lot more to that part of the plot than the film conveys.
Joe Zeff:
ROTFLMAO! The film was based on a short story, *The Sentinal,* By Arthur C. Clark,
I know, and there's several quite similar stories. Like a lot of authors, he seemed to do several variations on a theme.
who later wrote a novel *based on* the film.
Supposedly, the film and the novel were worked on concurrently.
Naturally, in that novelization, he had room to add considerable back-story and detail that wasn't in the film.
Supposedly, the first cut of the film was many hours long.
It's one of my favourites, but I have to be in a fairly lethargic mood to sit still and watch it uninterrupted.