Ragnara

Hey everyone, so far I am having 6 Artifacts. The ones missing are the ones from the Mobile Merchant and from the Researchstations. I figure I'll meet the right Merchant sooner or later. But so far I have only seen one Researchstation a while ago. I can't seem to find another one again. Are there any requirements like a certain distance from the core? Energy or mass fields? ---- Edit: Turns out I was just not paying attention and they're actually not that rare in the usual colonized space all along