Depends on what ship you're using.. I spiffed around a bit with trade runs and racked up some coin then went and bought the Pirhanna fighter.. it kept me going till I got the Anubis from the order. Max out your sheilds and repair items and weapons .. you should be ok then..

Done, Done, and Done. Flying the Anibus with maxed out everything with the results stated.

The Fangman

try instead of shooting those generators from afar , try it very close up, since its easier that way, and most of your guns will hit then, select them from your target list and go after them, dont go searching for them yourself..
as that will waste more time

your best bet is to ignore the nomads completely and just go after the generators

Yes, fly very close to them until distance says 0M and your weapons will be more effective. I knocked out all 3 generators with more than 5 minutes left. Use A and D button to move sideways around the generators while shooting.

It's almost simplest level, when you know the trick.
Destroying weapon platforms is particulary easy.
1. Cruise, then thrust to the WP avoiding shots.
2. Fly between columns using thruster, then stop, wait until your shield recharges.
3. make yourself comfortible - nasties won't hit you more then few times - shields will protect you
with no problem.
4. When you feel ready - destroy platform, then goto 1

--
hail

A few simple tips and tricks which i used...
- Strong(non-laser) Weapons with Torpedos and Stinger missiles...

Go to the ball-like planet and fly into the valley and spot the generators...(dont mistake the satelites which i wasted 30 torpedos :p)
Hover on the stem of the generators going back and forth... and just shoot.. and fill up your shield when it's down... brute force but it works...
Finally fly into the mission waypoint(the hole) and go through the fan and retrieve the source... and off u go...
Make sure you have about 2 mins of time to make your getaway...