Andrew Nicol plans out each shot of the film and hides small symbols in it to demonstrate a deeper meaning and or an idea, this is called symbolism and it plays a part in much of gattaca.
Gattaca is a film where a man must overcome the limits set by society and his own image of himself to achieve what should have been impossible.
The entirety of the movie revolves around space and Vincent’s goal to get to one of Jupiter’s moons Titan, which in turn revolves around the company / space agency that the film is named after, Gattaca.
Often when Gattaca appears in camera, far above the building there is a rocket departing for space. There are roughly 12 or more launches every day and as Irene says mid way through the film, “You’re the only one that watches all of them.”
He is the only person in the whole agency including the director who watches each rocket and takes none of them for granted, it is his dream it is his goal.
Those rockets symbolise Vincent’s dreams, his aspirations and his undying ambition to one day board that rocket and leave for the stars, To neglect the rockets that fly above him is to neglect everything he is aiming to achieve and if he loses his aspirations to be better than he is no better than those that he works with.