THE BROKEN JUMP GATE:

Every race has two special ships - a Destroyer and a Carrier.  The Destroyer shows up on the sector radar as a red symbol, something like an arrow in a box; the Carrier is a set of blue dots, also in
a box.  (The Teladi Phoenix is the Teladi Destroyer.)  Carriers carry LOTS of fighters.
The Argon Destroyer tells you:
a. The jump gate to Earth is suspected to be somewhere in Xenon territory, and is broken.
b. It is feared that the Xenons are preparing to attack, and we need to launch a pre-emptive strike
c. You have been selected to enter Xenon territory and find the jump gate (it looks like spacecraft debris).
d. It would be a good idea to contact all the races' Carriers and ask them to give you some help.
Your success in part (d.) will depend heavily on your reputation with that race.  Might be a good idea to kill a few more Xenons in their territory until they really love you.
When you find the jump gate, report back to Argon Destroyer.
(There's more, but I haven't gotten that far yet.