[TrevorW]

Why destroy a good action sci-fi story with logic and real science, maybe one day they'll make a movie that conforms to known reality, but I doubt it ???

This was the thing that got me about the first Alien movie, man with unknown obviously unfriendly creature stuck on face and how easily it was for someone to overide quarantine guidelines with no thought for the rest of the crew or what may go wrong.

Unknown never before encoutered species, hey man let it in ???

As with Aliens, perfectly good drop ship the all clear hasn't been called as the marines investigate the plant etc but we will set down our drop ship for a smoko and have a look around leaving it open so good old Alien can sneak aboard.