When you get the map for Serenity, go to a building with a portal in it and a bunch of alien Drones will come out of it. Here is a list of weapons to do this.

MP5K-A4 Sub-Machine gun
SCAR Assault Rifle
SMAW Rocket Launcher
SPAS 12 Shotgun
Strike Rifle
USP45 Pistol

Like I told, go into a room with a portal in it. A Drone will come out. Use your close up/scope mode with one of the weapons. Kill it, go out of the building, go in again, and then another Drone will come. Do that over and over and over again until you are tired and want to get back. Use the ASE on the portal you came out of to get here and go through the portal to get back to Atlantis.