You have to get a grasp on the scale of the cosmos to understand what I mean. To get to the nearest star system, alpha centauri, you would need a matter/antimatter reactor that would turn approximately 10 kilograms of mass into pure energy to approach .8c, where c is the speed of light ( and the assumption here is that we acheive near 100 percent efficiency in our propulsion mechanism, which is impossible). Any society capbable of doing so would be far beyond celestial scavenging for a few trinkets, in the same manner that our global economy is beyond scavenging for artifacts from brazilian tribal rituals, historical curiousity notwithstanding.