79 Egg Chamber is an underground launch area

If you look at the walls of the underground launch area in the latest trailer you can see the kind of 'open mouth' features in the ribbed walls. Just like the walls of the '79 Alien Egg Chamber. http://www.prometheus-movie.com/community/forums/topic/1875 So I suggest the '79 Alien derelict really is a lot older than the Pro derelict as the 'temple' structure has eroded away, and the '79 Alien derelict had a 'failure to launch' scenario. One of those 1% of launches when the SJs bio-tools malfunction and infect/kill an SJ.