Visiting an unexplored system with science ship (or observing one with sensors) reveals the existence of features such as habitable planets, megastructures and gateways. This information is somehow forgotten, if there is no one observing the system. In the start of the game I tend to use at least one science ship to boldly go where no one has been before and quickly find the important systems. It would be nice if the game would keep track of these known features, even if they are not surveyed yet.