Mr. Laser Beam wrote:
And who's to say Ripley didn't just make a mistake?
Her belief may have simply been based on evidence which indicated that the derelict crashed on the planetoid. That's something that seems like it's going to happen in Prometheus
. The Nostromo
crew didn't have the freedom to e.g. process samples brought back from the derelict, say for isotope comparisons with the planetoid, because their science officer was compromised.