A transmission... Out here?

Not at all, but it puts a certain spin on the entire venture. Weyland's expenditure to send Prometheus out there would have been crippling if it didn't pay off. The legalities of paying settlements to the bereaved as well as the total loss of any return would also tend to put a damper on corporate stocks. If Weyland was forced to reposition themselves in order to covertly investigate the Zeta Reticuli system, and see what happened to their expediton why did they wait three decades? It may have been in the outer rim but apparently it was along the route between Thedus and Sol.

I see what your saying, however, any scientific expedition to an unknown region of space would come with inherent risks. Risks that would be assessed by the company and insured against. A total loss of all equipment and crew could be acceptable when the potential for scientific discovery is so high and possibly profitable. Why the company would wait three decades to finally collect a specimen might just be a matter of waiting for the right combination of elements to come together. The right ship crewed by expendable employees who follow orders while remaining relatively ignorant to the dangers before them. Then having that ship pass by system at the right time to warrant a detour to "investigate" an alien transmission. you also have to consider that Kane's orders were to bring back a lifeform meaning the company knew what was there. W-Y waited so long so they could retrieve a specimen covertly. They just never considered one of the crew would blow everything to hell. Damn you Ripley.

Thats one of the significant questions for me. If WY are after something why wait 30 years. Considering Ash new everything why the caution. Why not just go and get it? I bet this wont be answered here. A second prequel will be needed.

you have to understand, with suspended animation and the vastness of space, it really may take that long for one trip. one thing they don't really touch upon in alien is how these ships travel large distances and how long it really takes. and what the psychological effect of workers leaving their family for years and decades and never aging. if suspended animation is necessitated, than it can be assumed the trip may take at minimal months, perhaps even years. and with the speed i see nostromo going at, it must use a wormhole or *cringe* warp drives?

Maybe thats why WY setup in the Thedus system in the first place. Losing things in space is really easy after all. WY may have known that the Prometheus was lost in that area but werent sure exactly where and were confident that at some point in the future one of their ship would stumble across it. Which would explain why there were protocols in place where the Nostromo had to stop and render assistence.