How can I get more expedition modules?

I found some ruins with my explorer and let it dig around a bit. But when I went with this explorer to a second site, I couldn't construct an expedition there.

I checked the Civilopedia and it said that expeditions consume expedition modules, and I noticed that my explorer didn't have any expedition modules left.

How can I get more expedition modules, so I simply have to built more explorers, or can I get them in any other way?

Solution 1:

Send your explorer back into one of your cities to gain another expedition module. It's similar to the way units in Civ5 have to go back to your territory to upgrade.

Additionally, there's a Virtue called Pathfinders in Tier II of the Prosperity tree that will give your explorers 3 more expedition modules. Upon choosing this virtue, all your explorers will instantly receive 3 more modules regardless of their location.