Once some time passed without explorers coming by I realized no one would gain visibility on my core unless I let it happen - so I decided not to let it happen. It was nice knowing no one had the ability to spy on me during the darkest hours of the dogpile.
The copper mine was a really nice break indeed. I actually got two of them during the course of the game, though the one at Psamathe came too late to make much of a difference.

The copper mine was a really nice break indeed. I actually got two of them during the course of the game, though the one at Psamathe came too late to make much of a difference.