There are three entries under
Discovered that count toward this achievement and the first one counts toward the
achievement. The various animal
Species on the planet need to be scanned.
Sites are found by exploring, usually the name of the place shows up as you enter the area.
Samples are plants and things like that which can be pulled with your ship to collect them and trade them to allies. You can get quests to find one from Workshops and Outposts. If they offer a quest for something you already have, just press B and try again.