[Suicide Junkie]

It never really made sense to me that a starship passing by a system would detect ancient ruins on any planet that has them. Wouldn't it have to do special scans? Well, here's an idea in two parts - the first part can be implemented without the second.

Well, considering that the first ship who passes through the system takes a detailed tally of the mineral, organic, and rads value of each planet, and rates it on how nice it would be to life there... Its not too unreasonable that super-advanced technology still intact enough to be useful to the scientists could be seen from space.