Story-related, cannot miss.

The Unearthed mission is one of two missions you’ll open up after heading to Oberum III for the main quest, “In Their Footsteps.” In it, unsurprisingly, you’ll head to earth… well, the moon. Our moon. Complete these two mission to unlock this achievement:

• Final Glimpses (you need to do this for Entangled (20G) too)
• Unearthed

Also, do “Missed Beyond Measure” as well, you owe it to yourself.