After analyzing our capability to detect objects in the solar system, researchers have come to a conclusion that should be fairly obvious: Even if extraterrestrials left something in our solar system like the artifacts we’ve sent out into deep space, we almost certainly wouldn’t know they were there.
"The vastness of space, combined with our limited searches to date, implies that any remote unpiloted exploratory probes of extraterrestrial origin would likely remain untouched," Penn State researchers Jacob Haqq-Misra and Ravi Kumar Kopparapu write in a paper accepted for publication by the journal Acta Astronautica.
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