Logic says the crew can't have anything to do with Alien

TheNextLV426
MemberOvomorphApril 16, 20121662 Views22 RepliesThe crew can't be responsible for the LV-426 crash.
Prometheus is set 30 years prior to Alien as we know, but Zeta Reticuli II, the star cluster where LV-426 is apparently, is around 40 light years away.
That means, the signal wouldn't have reached Earth for another 10 years after the Nostromo. Its highly unlikely that company scientists would have discovered it immediately, instead it would have taken a few years to find it.
So the derelict on LV-426 must have happened at least 10 - 20 years before Prometheus