also, a fire extinguisher would no more violently propel you backwards into the wall of your spacecraft in a zero gravity environment than it would jerk you backwards here on earth. you are weightless in space but you do have the same mass as you do on earth. and mass is the relevant figure of interest when you are dealing with forces like fire extinguisher exhaust. nonetheless i do recommend GRAVITY for the marathon. we absolutely must have 3d. is there such a thing as makeshift IMAX conversion? is it asking too much?