DALLAS: Mother's interrupted the course of our journey.
DALLAS: She's programmed to do that should certain conditions arise. They have.
Right away, we see the control technology can exert upon the human crew. Mother alters the course with no direct orders from anyone on the ship, limiting the free will of those aboard the Nostromo. They have to follow Mother's new course or it'll be hitchhiking across space for them.
RIPLEY: Because there's still some things left to do.
DALLAS: Like what?
RIPLEY: We're blind on "B" and "C" Decks, the reserve power system is—
DALLAS: That's a bunch of horses***. We can take off without that.
RIPLEY: We can. You think that's a good idea?
DALLAS: I just want to get the hell out of here. All right?
Once the ship lands on the unknown planetoid, it immediately begins breaking down. If we see the planetoid as nature in its purest, most primordial form, and we look at the ship as the height of human technology, then we can clearly see which of these two forces is the most powerful here. (Hint: it's not human tech.)
ASH: I've designed this tracking device. You just set it to search for a moving object.
Once faced with an unknown creature of nature, the crew turns to the thing that helped them become the dominant species on their planet, technology. Notice that the tools have a primitive hunting quality to them: a net for catching and a cattle prod that looks suspiciously like a spear.
MOTHER: UNABLE TO COMPUTE / AVAILABLE DATA INSUFFICIENT
DALLAS: WHAT ARE MY CHANCES?
MOTHER: DOES NOT COMPUTE.
Well, someone sounds like she needs a hard reboot. That's the thing about technology; it's created to solve previously encountered problems. A new threat requires new pathways, hence the data being insufficient.
RIPLEY: Ash? Any suggestions from you or Mother?
ASH: No. We're still collating.
RIPLEY: You're what? You're still collating? I find that hard to believe.
ASH: What would you like me to do?
RIPLEY: Just what you've been doing, Ash—nothing.
Ripley doesn't know yet that Ash is a robot, but she's basically calling out the technology that is supposed to protect them. Like a computer shackled with Windows 8, this tech just isn't doing the job. Also, notice how Ash says, "we're," implying a grouping between them that excludes the other crew members.
RIPLEY: REQUEST CLARIFICATION ON SCIENCE INABILITY TO NEUTRALIZE ALIEN
MOTHER: UNABLE TO CLARIFY
Up until this point, technology hasn't been helping, exactly, but it hasn't been hurting the crew either. It's been more or less value-neutral. Here, Ripley finally learns that their protective technological bubble and resident robot (Ash), have been actively working against the crew to keep the alien safe. It makes the route change in the beginning take on a whole new, sinister vibe.
MOTHER: The option to override detonation procedure has now expired.
RIPLEY: Mother, turn the cooling unit back on! Mother!
MOTHER: The ship will automatically destruct in T-minus five minutes.
RIPLEY: You b****!
Talk about a refrigerator mother: despite her name, Mother is obviously a bit cold-hearted. She might take care of the crew, but she certainly doesn't care about them. That does not compute.
RIPLEY: You… Are my lucky star… You, you're my lucky star. You are my lucky star. Oh, God!
By the movie's end, Ripley has returned things to "normal" by asserting mankind's technological dominance over nature. She uses the tools of a space suit, a grappling hook, and a space ship engine to blast the creature into space, where we assume it dies. It is dead, right? Right??