Without giving any specific spoilers, the game has a primarily archaeological feel, you will be following breadcrumbs around to various places in the solar system (your journal is important!!!) and learning about the ancient civilization that mysteriously disappeared. finally piecing together the whole picture is one of the most powerful moments I've ever had in gaming. while there are some NPCs to talk to, the game is primarily driven by your own exploration and the knowledge you pick up along the way.
there's no "correct order" to do things in, so if you feel like you've hit a dead end or you can't figure out what you should be doing at a particular place, consider going somewhere else. and most importantly: follow your curiosity