According to IGN, For the first time, director Sir Ridley Scott has gone into a little bit of detail for his upcoming prequel to Alien.
Talking to Empire at a premiere, he was asked if the movie would tell the story of how the extra-terrestrial critters found their way to LV-426 -- the infested planet that John Hurt, Sigourney Weaver and Co. discovered at the beginning of Alien.
Apparently not: "It's a brand new box of tricks," said Scott. "We know what the road map is, and the screenplay is now being put on paper. The prequel will be a while ago."
He went on: "It's very difficult to put a year on Alien, but [for example] if Alien was towards the end of this century, then the prequel story will take place 30-years prior."
How this fits into Alien lore we're not sure, but Scott is certainly excited by the project: "I never thought I'd look forward to a sequel. But a prequel is kind of interesting. I'm looking forward to doing that."
Thanks to IGN for the info.