In any case, Ebert's review included an insight that really hit home with me and, upon reflection, reveals why I've long associated Alien with Traveller, even though there's not a great deal of connection between the two. Ebert says:
A peculiarity of the rest of the actors is that none of them were particularly young. Tom Skerritt, the captain, was 46, Hurt was 39 but looked older, Holm was 48, Harry Dean Stanton was 53, Yaphet Kotto was 42, and only Veronica Cartwright at 29 and Weaver at 30 were in the age range of the usual thriller cast. Many recent action pictures have improbably young actors cast as key roles or sidekicks, but by skewing older, "Alien" achieves a certain texture without even making a point of it: These are not adventurers but workers, hired by a company to return 20 million tons of ore to Earth ...I suppose it doesn't get more clear than that.