This side-mission can be found by entering the Normandy’s galaxy map and having the ship travel to the following location:
Hourglass Nebula > Ploitari > Zanethu.
Scan the planet and locate the anomoly to begin the mission.
From the start move towards the center of the ship until the structure gives way a bit. Afterwards, make your way down the angled girder to the room inside the ship below. This platform has a pair of possible paths leading away from it along beams.
Head down the beam to the right and down to the next platform below. When you reach the edge and can go no further, look up and to the left to see a hanging piece of debris. Shoot this and it will drop to create a bridge.
Cross this and grab the canister of Refined Iridium . Climb the next beam here and again take the beam leading upwards when you reach a small platform. At the top, turn right and grab the canister of Refined Iridium here.
Climb up onto the debris next to the canister you just grabbed and follow the beam here to the end. Hop up onto the hull of the ship here (this can be tricky as the cover jump doesn’t always seem to work, but keep trying and you’ll get it eventually!). Turn to the left and follow the path along the top of the ship until you reach the far end.
Continue down the beams here back into the ship, and collect the container of Refined Iridium before heading down the stairs. Once the stairs collapse, turn around and grab another canister of Refined Iridium. Climb the stairs to the right and follow the path over to the large room at the front of the ship with the glowing red light.
As you arrive, interact with the mainframe monitor here to complete the mission.