Prerequisite: Can be unlocked immediately after touching down in Voeld.
Head to the center of the map, where the original signal of the Periphona has been detected. After reaching the area and updating Cora Harper: Asari Ark quest, look around to find a smoke emanating from the valley. Head there to find some resistance fighters in battle with the kett.
Take out the kett then talk to the survivors. Once done, a second wave of kett reinforcements will arrive. Take them out as well to complete this mission and obtain good exp.