Why does the lone engineer decide to go into the prometheus ship?

It's a monster flick, Hulk smash. More seriously, He killed everyone he saw but the chick who ran away. Then he was making a run for it to earth and someone busted up his ride. It seems he would look for anything tangibly habitable near the crash site. If anyone is still around, that's the best place to look. Also, it is a bit of an omage to the final scene in Alien when Ripley blows the Alien out into space.

My theory about the engineer going the "wrong way" (heading towards the life-boat instead of the next juggernaut down the line): 1) He could only survive a certain amount of time without life-support so the life-boat was closer and he might have assumed that he would be able to find safety there (of course his Juggernaut was fine too but probably wasn't a safe place to be what with the cargo it had on board) 2) David, in Engineerish, told the engineer that they had refreshments & alcohol over at the life-boat. 3) The engineer has sophisticated scanner and saw what was playing out whilst doing the roly-poly so he decided to "Kill All Humans" (someone in another thread said this so I've adopted it)

Whoever crashed his ship was a threat. There were 'many other ships - according to Dave. He had to first eliminate the threat before acquisitioning another ship

I think he was super pissed off that a puny worthless human actually managed to trash one of his ships. If a fly found a way to destroy your car you would probably want to go find it and kill it also.

why has noone asked how he could breath on the planets surface more to the point......or do we imagine he still had his helmet on by the time he shut the life raft airlock?

... because he was pi$$ed off! Ever had a fight or been smacked - you act irrationally - I would surmise that they have the same DNA and seem very aggressive - totally alpha...

Hey Mark, the most poisonous content of that planet's atmosphere (so was stated in movie) was CO2. Other ship only needed to be a good run away to make it.....which it was.

i just have a quick question, was all the air on that planet breathable? because i know inside the ship it was, but on the outside they always had their helmets on. if so, the engineer wouldnt of been able to breath. i do remember at the end the life support in shaws suit saying it only had to minutes of air left..so?...how did the engineer breath.

If you remember, the medical doctor at the beginning says you'd make it about 2 minutes in that atmosphere before dying. She says it would be like breathing through an exhaust pipe, which won't kill you instantly.

This is the problem I have with much of this film....the fact that we have to find a plausible explanation for most of the narrative gaps and flaws. It's just shitty writing guys, half the people seem to be in denial about this whereas the other half seem to be in agreement this is the fundamental reason they hated the film. Isn't a tight narrative the key to Great thought provoking film? If half the audience is sitting there racking up a list of flaws....you kind of failed.

Except half the flaws not dealing with Filfield are not flaws, just that people missed something. Such as david being in the same spot after the crash (he was not), how did they magically go to the temple (the scanners found metal, and they went to it.) and so on. As for this, its not logical that if your ship was eliminated (and carrying toxic cargo) you would 1) get out of the ship 2) eliminate the threat before going to the next ship..

What threat, there was nothing left to take another ship down. Personally I think the threat was more likely the squid than Shaw, I think it's possible that David told him about it and then convinced Shaw he was coming for her.

because movie is dumb dumb

".. think he was super pissed off .." After reading all of then post to me this seems like right 'answer'..with the information we have.. And he wanted revenge...and to eliminate any humans he could fine. Later he go to other Juggernauts.. In thinking this through it is hard to belive that any destructuion of a Juggernaut.would trigger a warning to the Engineer's home base..and help wul;d be on it's way. So I foresee a rescue'/investigative mission from the Creator's home planet to this moon and then a Engineer/Goo filled 'Death Star' to go to Earth and kill all humans!

Or it is possible that the engineers have no females in their race. Therefore they would be naturally curious about Shaw, so rather than go and kill her he wanted to study her. We all assume that they wanted to come to Earth and kill us, it is possible that they only wished to purge us. Much like you do to a cane field, you burn it to get rid off all the snakes etc, then you harvest and the left over mulch is sewn back in to the earth as nutrients to replenish the ground. Again we all assume that because they are bipedal and humanoid that their repiratory systems are the same as our own. Which of course is typical human reasoning. The point of this movie I believe is that we should not make assumptions. The first alien, well, I believe as do some others that it is there only as an answer to an age old question. Where did they come from? Again we are assuming that this xeno is malevolent, yet it has teth more of a herbivore than a carnivore. So one could suggest that is could easily live on the planet. Xeno's don't appear to be technologically minded, so I doubt it would learn to fly the space craft, although this one is born of an engineer so it is possible that it has some understanding of technology.