[@Dark Wind]I don't know any free ones of the top of my head, but as with many things, 10 minutes with google would answer that.

Never heard of Inkarnate though but the map looks good. does it have Sci-Fi elements to it (specifically a solar system map of planets, artificial installations, and the like?) otherwise this would be something I could use for the planet my current deviantart series is using. saves me the trouble of having to describe the environment.