Time Travel Possibility in Plot

Okay...so we see the derelict ship crashing on a planet or moon that can be described as the final resting place which we see in Alien. Now according to Alan Dean Foster, the derelict ship has been there for a million years. So, here is a theory, not only did they, the "engineers" have power to create but also the ability to travel back in time. So, what happens, everything in this space exploration goes horribly wrong and the "creation" crews up, so the "engineers" decide to go back in time and destroy it's "creation" in it;s infancy..which would destroy the history, as if we never were around. So, some crew members manage to destroy the ship as we see in the trailer and it crashes into the moon, which is now LV426 respectfully, of course the remaining crew members are left in this time, also to face the offspring of the derelict. So, this story takes place 30 years before the events of the Nostromo account. Through the million years, the moon changed. This would perhaps fit in line with the novel by Foster.