Go to the Docks Holding Area and locate the Preacher in Cargo Hold: C (point 7).
Pay attention to the dialogue and you will start the Pillars of Strength side mission.
When to start
After Priority: Palaven
“A batarian refugee needs the Pillar of Strength to improve his peoples morale.
Find the pillars in the Kites Nest and return to him at the Citadel refugee camp.”
Batarian Fleet War Asset
To complete this mission, go to Normandy, and using the Galaxy Map, travel to Kites Nest and scan Kharshan.
Enter the orbit, and continue to scan the planet until you reach the spot where the Pillars of Strength are located.
Retrieve them and take them back to the Preacher in the Citadel.