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.