The Peter Weyland Files from Prometheus Blu-Ray
Reveal that Peter,David and Weyland's team (except prometheus crew) know about LV-426 Signal before go LV-223
"As fate would have it, Shaw and Holloway's interest in Zeta 2 Reticuli has proven to be mutually beneficial. While the good doctors rely on ancient carvings and primitive cave paintings, my science division's own long range scans have recently detected a faint, almost imperceptible signal emanating from of the lesser moons in that system. And contrary to the findings of shaw and Holloway, which target LV-223 as our primary site of interest, our findings suggest the point of origin could actually be the moon LV-426.
Per standard procedure, we will embed a David 8 unit with the crew. And he will programmed with multiple contingency plans to address and exploit whatever assets we secure on 223. But only David will know about 426 and will ensure that the rest of the crew - including Meredith - learn nothing about the transmission we've recently discovered until the time is right."
also mural on Prometheus movies