I've said this before, but I think it is reasonable to hope that we'll find a burned out starship decellerator stage somewhere between Earth and Saturn. From a distance it would look like a small iron-nickle asteroid that was a few hundred meters in diameter. It might not have a regular shape after having been beat into wreckage by millions of years of meteor impact. It would have been very hot and radioactive shortly after being jettisoned but is probably now no more radioactive than any ordinary space rock with the same surface temperature. An elliptical orbit, very low density and a metallic surface are the things to look for.

Gary