In the movie Alien, of course, which I just watched again.
The exploratory party of Dallas, Lambert and Kane, the last of whom had been attacked and “infected” by a facehugger alien, were in the Nostromo airlock, requesting entry. Ripley, ranking officer inside the ship, refused, citing Company regs that required a 24-hour quarantine period. Of course Ash (who had his own agenda) opened the airlock door, and zany hijinks ensued.
But what if Ash hadn’t? Suppose Ripley immediately locked the door with a personal code that Ash couldn’t crack. The timeline in the movie is a little ambiguous. Would the chestburster have lethally emerged within 24 hours? I think that, if it did, it wouldn’t have been able to escape the airlock. Dallas and Lambert might have killed it with their sidearms (the alien’s acid would’ve burned through the hull, but it’s on the outer edge of the ship, so maybe that wouldn’t be too big of a problem). If it didn’t emerge within 24 hours, Kane would still be infected and a potential risk to the ship, and Ripley might keep them confined to the airlock even after that. If she let all of them back into the ship after 24 hours lapsed, then it wouldn’t be long before the chestburster came out, and events probably then unfold much as they did in the movie (except that Ash wouldn’t have gathered so much data on the facehugger).
Or maybe Dallas and Lambert, angry at Ripley and desperate to get Kane to the Medical Bay, would have used their sidearms to burn their way into the ship anyway.
What do you think?