I have read a little known manga called 2001 nights
recently, it harks back to the old hard scifi of Clarke and Asimov. Anyway, a certain chapter got me thinking about Prometheus;
We can expect the ship is going to travel a distance enough for time dilation to play a part, so I expect the ship may fly for years. Now a ship going for years with a crew needs alot of supplies. This is where you mileage may vary on matters;
Say the Prometheus is sent out as an exploration vessel, it is piloted and crewed by automated systems (androids?).
The actual people who will venture on new worlds are kept as donor eggs and sperm. These are then made into test tube babies once a planet is reached in orbit.
The android systems act as parents until the children are old enough to venture down to the planet. Very little resources will be needed, as the planet will be expected to sustain the humans when they go dirt-side.
I dont think this will happen in its entirety though!
It does explain a younger Shaw, if that is a true rumour, but how would time dilution be included in such a thing, unless the children are raised mid-trip, in a journey that may take from Earth POV more decades than a human could be useful as a crewmember.
Time dilation in the film will probably just justify the ship taking a long journey (of decades) whilst barely aging the crew and not turning it into a generation ship (as in the children of the original crew inherit the jobs of the old), mainly to the above post I have written about the ship supposed to be moving STL and planets that would feasibly hold extra-system alien races being more than a couple of tens of light years away.
Something to remember also, the Zeta-Reticuli binary system in RL lies about 12 light years away from Earth. Something to ponder on...