[joezydeco]

Well not just a plane passing overhead, a plane passing overhead 200 years from now.

Maybe we should be aiming the big laser at Oumuamua. With a big HEY COME BACK HERE message.

[rdtsc]

I've wondered if that was the purpose of the "probe". To see if anyone follows it, or otherwise interacts with it. Let's say you know there is a habitable planet, but you don't want to land there first, instead send a probe and see if the planet reacts to it. If they do, it would indicate a rather advanced civilization.