This side-mission can be found by entering the Normandy’s galaxy map and having the ship travel to the following location:
Rosetta Nebula > Enoch > Joab.
Scan the planet and locate the anomoly to begin the mission.
When you land you will see a sentry run into a nearby door to warn his buddies about your impending arrival. As soon as you regain control, run forward and into the cover in the area in front of the landing pad. Kill the various Blue Suns mercenaries that exit through the door. When the coast is clear, walk over to, and look to the right of the landing pad to find a pair of canisters containing Element Zero (one near some crates, the other between the two vehicles nearby). Go back and enter the door from whence the enemies came.
Upon entry, take cover and pop the mercs to the right and then kill the reinforcements that emerge from the door opposite your current position. Move into the room and clear out the baddies coming down the stairs on the right side of the room. When the area is safe, loot the room! Look between the pairs of beds on both the left and the right of the entry door for a personal locker at each location - there is a Med Kit on the table. Head up the stairs, take the first left at the top and open the locker here. Head to the very top of the ramp and through the door.
Clear the immediate area, before entering the room and heading left to kill a mini-boss - Lieutenant Locke and a few bodyguards. After the main man is dead, look around the room for some goodies. There is a canister of Element Zero and a PDA nearby that can be read to give you the location of a new side-mission.
Enter the next door and use the Prothean artefact here to complete the mission.