This is the first step for the exotic lament sword rewarded for the quest Lost Lament that you pick up at Banshee in the Tower.
For this part you will need to locate and scan three dead Exos on Europa. There are nine Exos in total but I will show you three that I have found and this is enough for this part of the quest.
You will find one in eventide ruins lost sector. It’s lying under the stairs in one of the rooms. You can complete this lost sector if you wish or head for another.
The other one I have found was in Concealed void lost sector. For this one you can also take a shortcut, or fight your way to the boss and once you kill it the barrier will open and you can scan it then.
The third one I have found was in Cadmus Ridge, to the left of this structure on top of a small hill.
And that is all you need for the first step of this quest. Hope this was useful and you have found yours.