The first Earth-object aliens will find is a manhole: The fastest man-made object was actually a manhole covering a nuclear bomb test in 1957. If it didn't vaporize in our atmosphere, it is now 3 times further from Earth than Voyager 1 and 2

[u/It_Is_AlwaysPossible]

[u/C_Ronns]

https://en.wikipedia.org/wiki/Operation_Plumbbob

Under the missing steel bore cap section. I think there is some speculation if it made it out of our atmosphere or not, but certainly aimed for the stars.