Prometheus Time line

Hey all, So the timeline in Prometheus has me a bit concerned, 30years before the events in Alien has me wondering why the crew of the Nostromo didn't put two and two together. I mean i would think that sending the out the top of the line scientific space ship and its crew to find out about humanities origins you would think that that could not be kept secret from the world news of the time. to me that would have been a big deal in earth current events, and it seems that the Prometheus crew is lost, and therefore, that would be a bigger event in earth history. So my point is.. the crew of Nostromo would have know about Prometheus either taught in school if it was before their birth or they would have lived through those events. Why didnt the Nostromo crew make a connection that the signal SOS/WARNING might be the lost Prometheus crew? This also brings up other ideas about how much Weland/Yutani knew of the signal and its origins. I think Weyland/Yutani knew or at least had a strong sense that this signal from Zeta Reticuli was from their lost Prometheus expedition and Nostromo was the closest ship in the area to investigate it. The company sent Nostromo crew to thier deaths, Ash knew 100 percent what was going on. Any ideas.