Writer Damon Lindelof discusses why Ridley Scott returned to the universe of Alien:
"My sense of it was that he felt like Alien and Blade Runner were enormously satisfying to him – so satisfying that he didn't need to do scifi any more. If he did it again, it was going to have to be different and special. But something happened over the course over the last 10 years, particularly with Alien. There was an itch he needed to scratch. Ridley always says that he was always very interested in the derelict spaceship and the space jockey that was piloting it. It was just something that sat in the back of his brain and never went away. So when the chance came up, he couldn't resist it. I wouldn't say he's a particularly spiritual, touchy-feely guy, but in talking to him I was surprised by the fact that he wanted to talk so much about what Prometheus would be about and what the characters wanted. Which is very different to the original Alien, where essentially the characters wanted to just not get killed."
"It was a very good script by Jon Spaihts. Essentially, what Jon had done was a much more dyed-in-the-wool Alien sequel, in that it had all the things in it that we would expect to be in an Alien movie, from face-huggers to chest-busters to eggs. But there were also some original ideas in there, too. And what I pitched to Ridley was, 'I don't think this movie needs the face-huggers and chest-busters and all the things people are going to be expecting. I think these other ideas are original enough to power the whole thing.'"
He confirms that the story follows two scientists - one of whom is star Noomi Rapace's Elizabeth Shaw - who find signs on the Isle of Skye pointing to a distant star system:
"Somehow. They convince others that this is a worthwhile adventure, so they go out there to find answers to the most fundamental questions we've had since we've had cognitive thought. Like, who am I? Who made me? What is the purpose of my life? That is the jumping-off point. And in all great science fiction and even myth, characters who try to cross a line that should not be crossed often pay very harsh consequences."
Finally, he confirms that sequels are a distinct possibility:
"One of the things we've always said, that makes Prometheus not a direct prequel of Alien, is that if there were a sequel to Prometheus – and, God willing, there will be if people like it – then it will not be Alien. This film ends in a way that goes off at a different tangent to the original Alien. If you see Alien straight after, you will see it in a context that didn't exist for you before, but it's not going to do anything to change the story of Alien. Prometheus has to go off in its own new bold direction, and hopefully it does so. Ridley certainly wants to do more."