Aliens: Infestation Help

ok, so im stuck on the Sulaco right now, more exactly, when you have to go on the zero space unit thingy and go outside. i have tried going all the way to the left but i run out of oxygen and die. and ive tried going to the tower thing but there is nothing there. so can someone tell me what to do??EDIT: nevermind, i found out :)

Please share

i just ran away from the aliens, trying not to get hit from them, you have to go all the way to the left, to where you have unvisited spots on the map