Escape from Paradise, Part I
Assuming that you have not been going through these steps at lightning speed, you probably heard something from your ship's SAIL concerning an "archaic energy source". Stock up on food and supplies, then follow SAIL's suggestion and search for this energy source. You may want to click on the quest bubble in the upper-right corner to make its compass appear over your hotbar rather than be hidden under it - this will also disclose the full details of your currently-tracked quest.
Keep going in the indicated direction, and you will soon come across some sort of ancient gateway. SAIL will intercept a message emanating from the structure asking for you to open a portal at the gateway and pass through it. However, the gateway needs 20 Core Fragments before it can open the portal.
At this point you have two options: either make your way down to the planet's core and harvest core fragments there or continue to explore the surface for another source of the fragments. As the first option does not require much explanation, this guide will focus on the second option.