Vice-Junior Representative Pay - Enough for another Orion's BELT. - 5 Plex.
Optimal Salesman - Seal the deal within 180 seconds of arriving at base. - 2500 Plex.
Silent Sage - Complete mission without using a Sage Ability. - 1000 Plex.
No Repair Costs - Complete mission without taking hull damage. - 1000 Plex.
You don't need to kill the base all the way; after you've gotten the Core's health low enough they'll surrender.