Breathing Air

Even if there was oxygen in the SJ ship why would you ever take off your helmet on an alien world, let alone in an alien space craft?

just to know whose scary expression is the best ;)

I believe Holloway is the astronaut to ask, he took his helmet off first!

yeah i thort the same...wot i don;t get if space jockey breathes the same air as us how can he breathe out side?..

Maybe they are able to determine upon landing that the atmosphere is breathable?

in alien, ash told dallas what the atmosphere was composed of...sure these guys do the same....also thinking this is not lv-426(or whatever the number was)

Spoiler Alert- if you haven't read Empire article: It reads"The helmets have headsets so the actors can hear each other, and are sleeker and more streamlined that the Alien vintage, but clearly modelled on the same principle by costume designer Janty Yates, And they play a crucial role in what unfolds, As the group spread out around a dark hole that leads God knows wher to who knows what. Holloway without warning, reaches up and takes his helmet off, despite Shaw's anguish pleas not to. "outside the structure, the air is lethal" explains Marshall-Green," but our suits tell us that inside the structure is reasonably similar to our atmosphere on earth. So i Leap before i look and taste the air." " This is on the same page as the Millburn photo. If it was me I wouldn't even take my helmet off on my own spaceship.

Because its a movie and seeing people in the helmets for too long is annoying

One other thing-the Blue Space Jockey's are only seen in the orrery room.There is a mutant on prometheus that doesn't have a helmet whereas the crew does.Also,if the air is different,how can they use the flamethrowers effectively? OK I admit the flamethrower is nit picking,however,Janek is in a scene on Prometheus along with numerous crew members and they all have the suits on.I'm thinking Prometheus survives the collision and they are stranded there until they get a derelict and use for an escape?Any thoughts?

We have the confirmation that the air is poisonous outside, but rendered harmless inside by the space jockeys. :) Flames just need 3 things: combustible, a source of dioxygen and heat. The planet's air must be filled with dioxygen, but thanks to large quantities of sulphur, carbon monoxide (that's an evil chemical that can't be smelled or detected by daily or conventional means) or some other gas, corrosive or not, the air is just lethal to certain living marco-organisms like trees or humans. As for the Promethean mutant, it can breathe the air thanks to a new set of lungs, or it merely is not taking a breather.

Would this not be the Atmospheric Processor technology that Weyland could of stolen? or has been put on the planet on a previous mission? ... maybe ...

"Would this not be the Atmospheric Processor technology that Weyland could of stolen?" What if he found it on earth?