Space age library research called Archaeology, greatly improves the museum.
And to speak with numbers...
I had 27000 fragments and 25000 blueprints when the event started. I crafted thousands of artifacts over the 2-3 last days and have more than 370,000XP, 18000 fragments and 70,000+ blueprints.
I can make 30,000 XP every 1,5 hour then I stop crafting and start looting cause I have depleted all food/gold and oil. It takes around 30 mins with a training blessing to do that.I rest and after a few hours, I can repeat that. I can do this process 3-4 times per day. That makes a total sum of 90,000-120,000 per day. And i assure you this is mild grinding. Not hardcore.
Now, how can I do that continuously? I craft 20 artifacts per batch job. I increase by 1 all artifact lines that are open AND by +2 all 3 star artifacts. I sell (thus getting back a big portion of what I spent) and repeat again. My fragments can stay high, stay the same for long periods and sometimes even increase! That allows for infinite crafting sessions. This is what makes a space age player able to craft so many artifacts and thus get so many XP.
As for atomic or global age players, they can do the same if they already have a nice big stash of fragments. Only downside is that they will deplete their fragments for sure at some point.
Now, pls excuse me but I have to craft some more....
TL DR: Museum is key in this. Research Archaelogy and craft like a madman! Increase everything by +1 and sell.